2024-03-28T11:19:22Z
https://zenodo.org/oai2d
oai:zenodo.org:4638956
2021-12-31T00:02:16Z
user-cib
Stefan Foord
Thabitha Magoele
2011-07-27
<p>The spread of invasive plant species and their impacts on plant communities have received international attention as global trade and global environmental change enhance the colonization and establishment of introduced species and threaten the integrity of native ecosystems. Because introduced species vary in their impact, studying the relationship between invasion and native communities is necessary to guide allocation of finite management resources. In this study abundance and distributional pattern of Agave sisalana surveyed in settlement areas and agricultural sites showed high significance levels in formation of clamps using T-test analysis, while comparison of natural area using One – Way ANOVA showed no significance levels in the formation of clamps.</p>
To determine the distibution of agave sisalana in some of the areas of vhembe district. To determine the perpose of introducing the species in the area of study. To test and obtain data that would enable comparision of agave per site area.
https://doi.org/10.5281/zenodo.4638956
oai:zenodo.org:4638956
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4638955
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Biological invasion
Alien plants
Species distribution
Vulnerability
Honours
The distrubution of agave sisala in vhembe district municipality
info:eu-repo/semantics/other
oai:zenodo.org:4751592
2021-12-31T00:02:14Z
user-cib
Chown, Steven
Janion, Charlene
2014-05-05
<p>Understanding the distribution, abundance and diversity of species and the mechanisms causing these patterns has been the interest of ecologists and taxonomists for decades. The exceptionally high plant diversity in the Fynbos biome has been well studied. Whilst early arguments suggested that the high plant diversity is not reflected in the arthropod diversity and that insect species richness is low compared to other comparable areas, these observations might have been hampered by the taxonomic impediment. Despite global recognition of the significance of this below-ground component of diversity for ecosystem functioning, soil is one of the most poorly studied habitats of terrestrial ecosystems. Although knowledge is increasing for epigaeic groups, other significant groups such as the Collembola remain especially poorly understood. This thesis starts addressing this serious gap in knowledge concerning the below-ground component of biodiversity in the Fynbos biome and the effects of landscape transformation thereon. As part of the work, considerable attention was given to resolving the taxonomic impediment for the springtail fauna of the Fynbos biome using modern morphological and DNA barcoding methods, while also examining the correlates of soil animal diversity in the biome, by using Collembola (springtails) as exemplars. First, using a combination of published records of Collembola from South Africa, various sampling methods and DNA barcoding, a species list is compiled for the Western Cape. Currently 213 species are known to exist from the Western Cape. A high level of cryptic diversity was also found in several genera, together with several potential species radiations in the Ectonura, Seira, Parisotoma and Cryptopygus.</p>
Submitted in fulfillment of degree of Doctor in Zoology
https://doi.org/10.5281/zenodo.4751592
oai:zenodo.org:4751592
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751591
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
springtail
Cape Floristic Region
PhD
Springtail Diversity in the Cape Floristic Region
info:eu-repo/semantics/other
oai:zenodo.org:4745645
2021-12-31T00:02:26Z
user-cib
Hui, Cang
Nuwagaba, Savannah
2013-08-13
Designing a mechanistic model that can give rise to realistic architecture of ecological networks is central to the understanding of how species assemble and function in ecosystems. As species are constantly adjusting their diets in an antagonistic network, we here incorporate this adaptive behaviour of diet choice into a bipartite network model, with the effect of antagonistic interactions between species depicted by Holling's type II functional response. Predictions of this model fit extremely well with the observed levels of nestedness, modularity and node-degree distributions for 61 real host-parasitoid and plant-herbivore networks. We further examined two specific scenarios of our model (species with identical [neutral] demographic parameters and interactions with identical [neutral] benefit in the network) and found that the demography-neutral scenario overestimated observed modularity, whilst the benefit neutral scenario overestimate observed nestedness. Relationships between nestedness, modularity and connectance were found strong. Moreover, in contrast to the common belief of the high modularity in antagonistic networks, most real networks (> 80%) are significantly nested, whilst nearly 40% of the real networks are surprisingly less compartmentalized than random networks generated from null models. Regardless of the controversy on whether antagonistic networks are nested or compartmentalized, the proposed model captured the essence of the dynamic nature of structural emergence in antagonistic networks. Due to its predictive power, this model was further used to investigate robustness in antagonistic networks. Predictions showed that the robustness of a network is determined by many factors, such as connectance, resource degree distribution, resource-consumer ratio, diversity, nestedness and compartmentalisation. Surprisingly, the manner of network response to species loss was independent of the sequence followed while removing species from a network. Variations were only noticed in the intensity of the effect resulting from the removals. In addition, we also showed that species extinction procedures which ignore the interaction switch underestimate the effect of any loss of species in these networks. We must therefore value our knowledge of possible adaptive processes in the ecosystem as they may be important for resolving the diversity-stability debate.
Submitted in fulfilment of an MSc degree.
https://doi.org/10.5281/zenodo.4745645
oai:zenodo.org:4745645
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745644
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Antagonistic networks
Nestedness and compartmentalisation
Masters
The Architecture of Antagonistic Networks
info:eu-repo/semantics/other
oai:zenodo.org:4675551
2021-12-31T00:02:05Z
user-cib
Cang Hui
Linke Potgieter
2010-09-16
<p>Spatial synchrony, which can be result of high migration, can increase the risk of regional extinction, and as a result reduce metapopulation persistence. Coupled patch models, based on a within-patch discrete growth model, are used to investigate the impact of predator pursuit (PP) and prey evasion (PE) on spatial synchrony and pattern formation in a metapopulation framework. Results show that PP and PE together can reduce spatial synchrony and thus the improvement of metapopulation persistence. PP and PE on their own do not signi¯cantly contribute towards asynchrony, however, they do contribute towards higher average population sizes, which in turn results in the improvement of metapopulation persistence. Spatially explicit predator-prey systems with local migration without PP and PE can produce self-organized spatial patterns such as spiral waves and circular waves. The e®ect of PP and PE on spatial pattern formation can decrease spatial synchrony and change the spiral and circular waves to spatial chaos which result in asynchrony of neighbouring patches and improve metapopulation persistence.</p>
https://doi.org/10.5281/zenodo.4675551
oai:zenodo.org:4675551
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4675550
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Ecological Modelling
Predator-Prey
Cellular Automation
Spatial Dynamics
Honours
Spatial pattern formation of a predator-prey system with predator pursuit and prey evasion
info:eu-repo/semantics/other
oai:zenodo.org:4745673
2021-12-31T00:02:06Z
openaire_data
user-cib
Weyl, Olaf
Van der Walt, Kerry Ann
2014-01-27
The Groot Marico catchment in the North West Province has been identified as a National freshwater Ecosystem Priority Area (NFEPA) and represents unique landscape features with unique biodiversity and has been identified as biodiversity special features of special ecological significance. However, there is little information with regards to the distribution of the species inhabiting the catchment.Three native freshwater species which have high local conservation importance, namely Amphilius uranoscopus, Chiloglanis pretoriae and Barbus motebensis have been selected for this study. Barbus motebensis is endemic to the catchment and is IUCN-listed as vulnerable (VUL). All three species within the catchment are thought to be impacted by natural discontinuities which can impact an organism's preferred habitat and result in population fragmentation. Furthermore, these three species may be impacted by non-native largemouth bass, Micropterus salmoides which through predation pressure may further fragment tributary populations of these species.
Therefore, the main problem is to distinguish between recent and historical fragmentation caused by either natural or human mediated processes, or a combination of both. This project aims to (1) determine whether tributary populations of the three species comprise of one genetic population or whether they are divided up into genetically distinct subpopulations; (2) assess population histories of the three native freshwater species in order to compare hypothetical past distribution to present distribution patterns and (3) lastly by making recommendations for prioritising conservation action. From these aims, the central null hypothesis is that there is no genetic differentiation between tributary populations of B. motebensis, A. Uranoscopus and C. pretoriae in the Groot Marico catchment, North West Province.
https://doi.org/10.5281/zenodo.4745673
oai:zenodo.org:4745673
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745672
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
DNA
ND2 and S7
Masters
Using genetic differentiation to determine conservation priority areas for three native fishes in the Groot Marico catchment, North West Province
info:eu-repo/semantics/other
oai:zenodo.org:7505288
2023-01-16T10:30:05Z
user-cib
Esler, Karen
Sitas, Nadia
Esler, Karen
Sitas, Nadia
Abrahams, Brent
2022-04-01
info:eu-repo/date/embargoEnd/2027-04-01
<p>The pervasiveness of threats posed by biological invasions presents significant challenges to human well-being, biodiversity conservation, and natural resource management, which has contributed to the growth of invasion science as a discipline. However, several studies have shown that the social-ecological complexity of invasions, the compartmentalisation of knowledge into disciplines and the lack of integrative research approaches, current invasion research has not informed management decision making effectively. Thus, to maximise the impact of research investments, there is a need to explore and evaluate how research informs management practices and processes linked to biological invasions. Accordingly, this dissertation outlines the state of invasion management-related research in South Africa, using the internationally recognised Working for Water (WfW) programme as a case study. Drawing on insights from science studies and evaluation research, a mixed-method approach is used to assess the processes, conditions and outputs associated with research produced under the programme’s auspices. The research comprised two areas of inquiry 1) the exploration of textual information (journal articles, grey literature, and their content), and 2) the social dimensions of research and decision making linked to invasion science and management, with a specific focus on collaborative relationships amongst scientists and decision makers. It sought to determine the extent to which published research aligned with the programme’s needs, research and management strategies. The research also aimed to identify effective ways for organising and producing knowledge relevant to decision making; and to provide insights into how the social dimensions, the people and organisations, their interactions and impact, have shaped research and decision-making processes. Findings suggest that there are significant gaps in the knowledge base particularly in relation to the social dimensions of biological invasions, which were poorly represented and aligned with the mandate and priorities set by the programme. This research showed significant deficiencies in knowledge management and the uptake of research funded by the programme, despite its potential relevance to decision making as evidenced by the recommendations presented in the research. Moreover, research produced under WfW’s auspices was authored by a handful of key researchers who fulfil a significant role in shaping research collaborations both across disciplines and institutions. The loss of these key individuals, including those involved in management-related decision making, would be detrimental to the stability of collaboration networks and research productivity. Finally, findings show that research productivity, collaborative relationships between scientists within and across research organisations, and between research and decision-making processes are positively influenced by collegiality and cooperation between actors, while increased competition and bureaucratisation in the workplace negatively influence research productivity. To address the shortcomings concerning the invasion research and management identified in this dissertation, efforts towards improving the relationship between researchers and decision-makers and building more resilient collaboration networks need to be implemented. Firstly, institutions must engage in and fund more targeted, long-term transdisciplinary or integrative research that incorporates appropriate structures that foster collaboration, knowledge coproduction and knowledge sharing. Secondly, systems and strategies for monitoring and evaluating research, including the use of bibliometric indicators, social network analyses and qualitative assessments, should be developed to ensure that research relevant to managing biological invasions is not lost to the decision-making process. Such an undertaking would in turn require the development of an integrated research strategy and action plan that accounts for both the knowledge management and the social processes underpinning research and decision making.</p>
https://doi.org/10.5281/zenodo.7505288
oai:zenodo.org:7505288
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.7505287
info:eu-repo/semantics/embargoedAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
biological invasions; decision making; knowing-doing gap; mixed methods; research evaluation; social network analysis; social processes; Working for Water programme
A mixed method approach towards the evaluation and assessment of integrative research programme outputs: The case of the Invasive Alien Plant management programme Working for Water
info:eu-repo/semantics/doctoralThesis
oai:zenodo.org:4761500
2021-12-31T00:02:17Z
openaire_data
user-cib
McGeoch, Melodie
Spear, Dian
Kleynhans, Elizabeth
Marais, Elrike
2012-03-07
<p>Database of invasive alien species (including plants, mammals, birds, fish and amphibians) present in 57 countries, with references for impact and spread information.</p>
This database was developed for populating the global indicator for invasive species.
https://doi.org/10.5281/zenodo.4761500
oai:zenodo.org:4761500
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761499
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
invasive species
database
impact
spread
Post-doc
Global Invasive Alien Species Indicator Database
info:eu-repo/semantics/other
oai:zenodo.org:4675587
2021-12-31T00:02:12Z
user-cib
Cang Hui
Martjin van der Merwe
2010-09-16
<p>At first glance the existence of altruism in nature seems paradoxical. In displaying an altruistic act, an individual incurs some cost to its own fitness. Natural selection favours the fittest individuals and one would expect that genes promoting altruism would be selected against. This report investigates the mechanisms that facilitates the evolution of altruism. Game theory is widely applied in the study of the evolution of altruism and cooperation. We review game theory concepts which occur regularly in the literature and which are important in the study ofthe evolution of cooperation. The Prisoner's Dilemma game capturesthe essence of altruism and is a model often employed in the theoreticalstudy of cooperation. The best strategy for both players in the single round Prisoner's Dillema (PD) game is to defect, but having repeated rounds can lead to the evolution of cooperation. The mechanism by which cooperation is established in this scenario is known as direct reciprocity. Another mechanism which promotes the evolution of cooperation is the non-random interaction of players, called assortment. A couple of factors could influence the assortment of players, one of which is the spatial distribution of players. A model is constructed in which the players in the PD are placed on a lattice. Each player adopts one of two strategies, pure cooperation or pure defection. The players propagate and die out in proportion to how well they do in playing the PD against their neighbours. The model is used to investigate the spatial dynamics of the players and the level of assortment achieved. A simple movement strategy is introduced, whereby players move if they encounter a defector. The effect of this movement on the assortment is investigated. Our results show that by placing the players in the PD on lattice, enough assortment can be gained to allow the persistence of cooperation. An increase in the dispersal parameter leads to a decline in the success of cooperators and a loss in assortment. This suggests that the best movement strategy for cooperators is to have low dispersal rates, while defectors gain a big benefit from higher dispersal rates.</p>
https://doi.org/10.5281/zenodo.4675587
oai:zenodo.org:4675587
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4675586
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Ecological Modelling
Altruism
Cellular Automata
Spatial Dynamics
Honours
The Evolution of Altruism - Spatial Assortment in the Prisoner's Dilemma
info:eu-repo/semantics/other
oai:zenodo.org:4761470
2021-12-31T00:02:15Z
openaire_data
user-cib
Chown, Steven
Braschler, Brigitte
2014-03-14
The files contain sequences and collection information from a project on barcoding South African ants. Parts of the collections were done for this purpose while other samples were derived from different ant projects in which the author was involved during her stay at the CIB. Additional samples were received as donations by other researchers. The data can be combined with the diversity and trait information collected in those projects. This includes the two long-term monitoring projects - the Iimbovane Outreach project and the Cederberg Altitudinal Transect Project (aka Coast to Karoo Transect) - and projects using the same study sites. Sequencing of samples took place at the Biodiversity Institute of Ontario at the University of Guelph as this project was in collaboration with the international Barcoding of Life Initiative and its South African collaborators. The data thus is also stored in the Barcoding of Life Database and Aggregate files of the project's data have been compiled using the web tools of this database. Voucher specimens are stored in the collection of the CIB at Stellenbosch University.
The main intentions were to provide a first attempt at a phylogeny for ongoing ant projects at the CIB, test morphospecies hypotheses from these projects, and provide future researchers with an additional identification tool (the data is publicily accessable via the Barcoding of Life Database. While South Africa has a long history of ant research, a large portion of it's ant species are not yet named, distributions and intraspecific variation are often poorly known, and keys - where existing - are often not to modern standards and outdated. This makes ant identification challenging and lowers the possibility to combine data from different projects. The new tool of DNABarcoding may thus help adopt this ecologically important group more frequently in research and conservation work.
https://doi.org/10.5281/zenodo.4761470
oai:zenodo.org:4761470
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761469
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
ant
DNA barcode
formicidae
South Africa
biodiversity
Post-doc
DNA barcoding of South African Ants
info:eu-repo/semantics/other
oai:zenodo.org:4650190
2021-12-31T00:02:26Z
user-cib
Augustine Niba
Inam Yekwayo
2010-11-26
<p>The reproductive biology of giant periwinkle (Turbo sarmaticus) was investigated using gravimetric method. Samples were randomly collected from Dwesa-Cwebe Nature Reserve during spring low tide from June 1996 to July 1997 and preserved in 10% formalin seawater. A 2-way Analysis of Covariance (ANCOVA) test was used to test the effect of gender and month on the Gonado-Somatic Index (GSI) using the operculum diameter as covariate. The results indicated that the male GSI was grater than the female GSI and this was due to the selective predation. The results showed synchronized spawning period of both males and females. Results from Chi-squared tests showed a distortion from a 1:1 sex ratio with significantly more males than females. Males appeared to attain size at sexual maturity earlier than females. Spawning of T. sarmaticus occurred in warmer months and temperature was found to be the important factor triggering spawning. Information obtained from this study may possibly add value on the effective management of this species. Key words: Turbo sarmaticus, reproductive cycle, spawning period, sex ratio, sexual maturity.</p>
In partial fulfilment of the award of a BSc Honours Degree in Zoology
https://doi.org/10.5281/zenodo.4650190
oai:zenodo.org:4650190
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4650189
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Turbo sarmaticus
reproductive cycle
spawning period
sex ratio
sexual maturity
Honours
Reproductive biology of Turbo sarmaticus at Dwesa-Cwebe Nature Reserve
info:eu-repo/semantics/other
oai:zenodo.org:4745655
2021-12-31T00:02:10Z
openaire_data
user-cib
Somers, Michael
Purdon, Jean
2012-03-01
Hluhluwe-iMfolozi Park is home to a number of indigenous and endemic species. As its mandate is to protect and preserve biodiversity, any factors that may result in the loss of species should be monitored carefully. This study aims to look at two such factors; the alien invasive plant Chromolaena odorata and intensive grazing by large mammalian ungulates (resulting in grazing lawns). Disturbances such as these typically result in the modification in the structural complexity of the habitat which in turn affects its associated fauna. This study compared the structural change of these two disturbances and their adjacent uninvaded habitats and bunch grass habitats respectively. By using a set of manipulated and mensurative (natural) treatments the change in habitat structural complexity was then related to ant diversity, assemblage formation, competitive interactions, resource acquisition, resource monopolisation and ant body size.
Both disturbances revealed that structural complexity within the natural experiments did not significantly alter ant assemblage composition, diversity or competitive interactions. However, at microhabitat scale, as was exhibited by manipulated treatments, structural complexity did appear to play a role in the organisation of ant communities, their competitive interactions and body size. The baited traps which were less complex in structure tended to support the larger species of ants which acquired resources at a faster rate and in higher numbers.
Assemblage composition of ants and the diversity of ants were not significantly altered by C. odorata. This could suggest that ants respond to structural complexity rather than plant species richness. Therefore it would be wise to employ the use of other biological indicators such as spiders to test the effect of alien invasive plants on ecosystems. On the other hand, as a result of heavy grazing, a unique assemblage composition of ants was found on grazing lawns when compared with their adjacent bunch grass sites. This would suggest that grazing is a vital component of the savanna system as it adds heterogeneity to the system, resulting in a biodiversity increase.
To look at how C. odorata effects ant comminties by changing local biocomplexity.
https://doi.org/10.5281/zenodo.4745655
oai:zenodo.org:4745655
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745654
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Biocomplexity
ants
Masters
Interactions between habitat disturbances and complexity: the effect on ant communities
info:eu-repo/semantics/other
oai:zenodo.org:4748436
2021-12-31T00:02:22Z
openaire_data
user-cib
van Rensburg, Berndt
Harris, Kyle
2009-08-13
Invasive alien species are considered the second greatest threat to global biodiversity after habitat loss. South Africa is not immune from such threats and it is estimated that 10 million ha (8.28 %) of land has been invaded to some extent by invasive alien species. Although South Africa has been invaded by several taxa, it is the effect of invasive trees and shrubs that has been environmentally and economically most damaging. The concerns raised due to the effects of biological invasion are not only restricted to off-reserve areas, but also protected areas where invasive alien organisms often pose a greater threat than habitat loss. Kruger National Park (KNP), South Africa's flagship conservation area has been invaded by numerous plant taxa. The most damaging of these is Opuntia stricta (Cactaceae) and current sources estimate that the weed has invaded approximately 35 000 ha of conserved land, despite the initiation of a biological control programme against it. However, little is known about the effect of O. stricta on biodiversity in the KNP despite the large number of resources allocated to its eradication, including a successful biological control programme against it. In this study, I investigated the effect of O. stricta infestation on beetle (Order Coleoptera) and spider (Order Araneae) assemblages across four treatments of varying O. stricta infestation levels (heavy infestation, medium infestation, surrounded sites and pristine sites). Species characteristic of each treatment (indicator species) were identified using the indicator method. In addition, spiders were collected to gauge the effectiveness of three collecting methods (pitfall traps, leaf litter sifting and active searching) in a savanna characterized by O. stricta invasion. One hundred and thirty one spider species (1050 individuals) and 72 beetle species (2162 individuals) were collected in the treatments. I found no significant differences in species richness, species density and species assemblages for both beetles and spiders across the treatments. In addition, no beetle or spider species were found to be characteristic indicator species for a given treatment, which further indicates that arthropod assemblages are similar when compared across treatments. These results indicate that O. stricta does not appear to have a significant effect on beetle and spider assemblages at its current infestation level, possibly because of the similarity in vegetation structure across the treatments. Regarding spiders, different collecting methods captured different species and only 17 % of the species were shared, indicating that the methods complement each other. Therefore, in order to sample the spider community, all three methods should be employed. Of the 131 spider species collected, 54 species (41 %) are new records for the KNP. In light of the results, it is suggested that KNP's successful biological control programme has played an important role in reducing the extent of the O. stricta infestation and should be continued to further mitigate the impacts of O. stricta.
https://doi.org/10.5281/zenodo.4748436
oai:zenodo.org:4748436
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748435
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Zoology
Masters
Arthropod assemblages in a savanna invaded by Opuntia stricta (Cactaceae) in the Kruger National Park, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:5497459
2021-09-10T06:59:55Z
openaire_data
user-cib
Chown, Steven
Nortje, Erika
2021-09-09
<p>The Coast to Karoo Transect investigates the abundance and diversity of ants and beetles along an altitudinal gradient in the Cederberg mountains of the Western Cape, South Africa. It is a long term project, initiated in 2002 by Prof. S.L. Chown, Stellenbosch University. Data collection was carried out on a biannual (spring and autumn) basis.</p>
<p>To monitor changes in invertebrate assemblages, focusing on ants and beetles. Temperature data was collected with i-buttons and a Hobo data logger. Data set ends Sept 2020.</p>
https://doi.org/10.5281/zenodo.5497459
oai:zenodo.org:5497459
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.5497458
info:eu-repo/semantics/restrictedAccess
altitudinal gradient; climate change; i-button, Longterm Data
Cederberg Climate Data 2019-2020
info:eu-repo/semantics/other
oai:zenodo.org:4761482
2021-05-14T13:48:13Z
openaire_data
user-cib
McGeoch, Melodie
Kalwij, Jesse
2008-07-04
File belonging to Kalwij et al 2008. This is a multivariate dataset at the plot level (n=240) whereby the Braun-Blanquet cover estimation of exotic species is listed for each plot. In addition a sheet with environmental data at the plot level is provided. An explaination of the environmental variables is provided in an included metadatasheet.
These data were used to conduct the multivariate analysis for Kalwij et al 2008 at the plot level in Canoco 4.5
https://doi.org/10.5281/zenodo.4761482
oai:zenodo.org:4761482
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761481
info:eu-repo/semantics/restrictedAccess
Botany
Post-doc
Karoo road verge study: Plot level sample data
info:eu-repo/semantics/other
oai:zenodo.org:4761509
2021-12-31T00:02:13Z
openaire_data
user-cib
McGeoch, Melodie
Spear, Dian
2012-03-07
See McGeoch et al. 2012 Ecol Applications. Experts were sent lists of aliens (for different taxa in different countries) and asked to assess the lists for whether they agreed, did not agree or did not know whether the species should be listed as alien for that country. Experts were also asked to add species to lists. The lists assessed were those compiled for the global invasive alien species indicator database.
https://doi.org/10.5281/zenodo.4761509
oai:zenodo.org:4761509
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761508
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Post-doc
Summary of responses from experts that assessed lists of alien species for different countries
info:eu-repo/semantics/other
oai:zenodo.org:4761488
2021-05-14T13:48:13Z
openaire_data
user-cib
Measey, John
Kruger, Natasha
Vimercati, Giovanni
Herrel, Anthony
Secondi, Jean
2020-09-28
info:eu-repo/date/embargoEnd/2025-09-28
<p>In amphibians, spatial sorting progressively enhances the dispersal capacities of dispersing stages in expanding populations but may enhance or limit the performance of the earlier non-dispersing stages. Phenotypic traits of non-dispersing tadpoles and metamorphs can be coupled, through carryover effects and trade-offs, or decoupled to dispersal traits in adults. We used the globally invasive amphibian, Xenopus laevis, to examine whether spatial sorting of adult phenotypes affects the phenotype of larval stages to metamorphosis in the core and at the periphery of an invasive population in France. We combined common garden laboratory and outdoor experiments to test the effect of parental pond location (core or periphery) on morphology, development and survival to metamorphosis and found no differences between tadpoles. After metamorphosis, the only difference observed in either of the experiments was the larger body size of metamorphs from the periphery, and then only when reared in the laboratory. Differences in metamorph size may indicate that a shift of dispersal traits occur after metamorphosis in X. laevis. Thus, our findings illustrate that decoupled evolution through spatial sorting can lead to changes of X. laevis adult phenotypes that would enhance dispersal without affecting the phenotype of tadpoles before metamorphosis.</p>
https://doi.org/10.5281/zenodo.4761488
oai:zenodo.org:4761488
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761487
info:eu-repo/semantics/embargoedAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Anura, decoupling, development, dispersal, metamorph, morphology, Pipidae, survival, tadpoles.
Post-doc
Does the spatial sorting of dispersal traits affect the phenotype of the non-dispersing stages of the invasive frog Xenopus laevis through coupling?
info:eu-repo/semantics/other
oai:zenodo.org:4740291
2022-02-17T00:02:00Z
openaire_data
user-cib
Measey, John
Rebelo, Alexander Douglas
2017-02-17
The phenotypic diversity between closely related species is often attributed to the process of natural selection. This process retains heritable traits within a population which increases the survival and reproductive output of an organism. Most animals rely on locomotion for basic and vital tasks, and thus require effective movement within the environment they occupy. Selection on morphological traits can result in adaptations that influence aspects of locomotion to better suit their requirements. Locomotion, in addition to other traits such as body size, is hypothesised to also have an effect on distributional patterns, and could drive large-scale macroecological patterns. Understanding how interspecific differences in morphology relate to functional, adaptive and distribution patterns can provide clues to the evolutionary and macroecological processes that drive them.
In this study I compare interspecific differences in morphology and locomotor performance of the Pyxicephalidae, a recent frog radiation within sub-Saharan Africa that has given rise to remarkable morphological and ecological diversity. I hypothesise that morphology will affect locomotor performance in accordance with simple biomechanical predictions and findings from studies on other anurans. Furthermore, I categorise the habitat and ecology of each species into different frog ecotypes. I hypothesise that species differences in both morphology and locomotor traits correspond to changes in the ecotype. Additionally I determine the geographic range size of pyxicephalid species to investigate whether interspecific differences in morphological and reproductive traits can explain differences in range sizes. By using climatic and topographic variables, I model species distribution and niche breadth to account for habitat difference between species to test hypotheses of colonisation and dispersal. I hypothesise that the selected morphological and reproductive traits will correlate with species range size and that these correlations persist in either colonisation ability or niche breadth.
I captured five to ten individuals for each of 25 species of pyxicephalid frogs from their natural habitat across South Africa. Swimming and jumping performance was tested by filming frogs at 120 and 240 fps respectively, terrestrial and aquatic endurance was assessed by chasing frogs around a circular track for 20 and 15 minutes respectively and grip performance was measured by placing frogs on a non-stick surface that was rotated until the frog lost traction. Species ecotype was categorised using field observation from available literature as well as expert experience. Specimens were measured and dissected from museums to obtain morphological and reproductive traits. Range size was calculated using a minimum convex polygon for distribution data obtained from assessable databases and institutions. MaxEnt was used to model habitat suitability with Worldclim and topographic predictors. Colonisation Index was derived from habitat suitability to quantify the ability of a species to occupy nearby suitable habitats. In addition, niche breadth was calculated with the Outlier Mean Index (OMI) analysis, using the same predictor variables, but constraining the geographic extent to South African and species therein.
Species morphology had a significant influence on locomotor performance, which confirmed similar functional relationships found for other frog clades. Body size explained the greatest variation in performance across species, while hindlimb length was positively related to burst performance but negatively with persistent locomotion. Furthermore, I find support that separate selective optima between burrowing, terrestrial and semi-aquatic ecotypes have acted on overall morphology, but not on locomotor performance. However, specific tests between traits that have been linked to ecotypes in other anurans revealed that semi-aquatic and semi-arboreal ecotypes have specialised morphological adaptations, but only semi-aquatic ecotypes showed support for a performance optimum. Species geographic range size was positively correlated with body size and relative clutch size, but not relative head width or hindlimb length. The Colonisation Index was not robust for comparing species from different environments and range extents. Species niche breadth was not explained by either body size or relative clutch size, but by relative hindlimb length, suggesting that these former traits do not affect range size by increasing species ability to colonise and occupy a broader range of environmental conditions.
In summary, species body size and reproductive output are indirectly linked to range size patterns, but these patterns appear to be the result of an indirect association with abundant habitats or the ability to disperse and colonise within suitable habitat. The morphological diversity of the Pyxicephalidae has functional significance for locomotor performance, and some of these traits do represent ecotype adaptations. However, the limited evidence presented in this study does not support the 'exceptional' adaptive diversity indicative of an adaptive radiation within the Pyxicephalidae.
Completion of Masters degree, publish research papers (ongoing)
https://doi.org/10.5281/zenodo.4740291
oai:zenodo.org:4740291
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740290
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Pyxicephalidae
Morphology
Locomotion
Anura
Macroecology
range size
Masters
Investigating the morphology, locomotory performance and macroecology of a sub-Saharan African frog radiation (Anura: Pyxicephalidae)
info:eu-repo/semantics/other
oai:zenodo.org:4669996
2021-12-31T00:02:15Z
openaire_data
user-cib
Karen Esler
Matthys Strydom
2010-09-23
<p>Acacia saligna is the most damaging invasive species in the coastal lowlands of the south-western Cape. The gall rust fungus, Uromycladium tepperianum, has been highly successful as a biological control agent for A. saligna populations in South Africa and has effectively reduced the density, canopy cover and seed production of the tree. However, there are still concerns about the soil-stored seed bank and knowledge of seed bank status and dynamics is crucial for effective management. This study evaluated the effectiveness of two different sampling methods in assessing the status of the seed bank, how the seed bank of A. saligna at two different sites varies over time and how these findings compare to findings of other seed bank studies of A. saligna across southern Africa. Even with the reduction in seed production caused by biological control, numbers of seeds in the soil seed bank are high enough to maintain high levels of recruitment after management or natural disturbances. Both sampling methods (grid and random sampling) attempted were effective in assessing the vertical distribution of the seed bank and estimated the size of the seed bank to be within the same order of magnitude. However, random sampling will be more effective in assessing the seed bank size as it was found that the seeds have a clumped horizontal distribution. The vertical distribution of seeds in the seed bank was found to be influenced by soil properties. The largest portion of the seed bank is situated in the upper 0-10 cm of the soil and declines in size with depth.</p>
To fulfill 4th year honours project
https://doi.org/10.5281/zenodo.4669996
oai:zenodo.org:4669996
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4669995
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Acacia saligna
seed bank
sampling methods
vertical distribution
horizontal distribution
Honours
Seed bank status and dynamics of Acacia saligna at two sites in the Western Cape, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4650053
2021-12-31T00:02:20Z
openaire_data
user-cib
Augustine Niba
Andiswa Jafta
2010-11-26
<p>Rastrineobola argentae, commonly known as the silver cyprinid, it is a protogynous diandric teleost fish endemic to Lake Victoria in East Africa. R. argentea is a small, fast-swimming fish rarely reaching a length of greater than 8cm in standard length. Its body is slender and compressed. The fish is very hardy and reproduces all year round making it a good candidate for studying developmental processes. Following the introduction of exotic and predatory fish in the 1950’s in Lake Victoria, the silver cyprinid is one of the endemic fish species that has remained unaffected. The lake is now dominated by three fish species; Lates niloticus. an introduced predator; Oreochromis niloticus, an exotic herbivore and Rastrineobola argentea, an indigenous zooplanktivore. The purpose of this work was to to obtain information on age, growth and to describe oocyte developmental stages in the silver cyprinid, Rastrineobola argentea inhabiting the Nyanza Gulf of lake Victoria and relate this information to the reproductive biology of the species. Fish were sampled, fixed and processed for histology using standard histological procedures. The current study has revealed that there is a positive correlation between length and mass of Rastrineobola argentea and state of gonad development. Stages of oocyte developmental stages are similar to those described for other teleosts fish. Gonads were classified into three reproductive states: immature, maturing and mature. All fish sampled in this study were females except in size class G (> 50 mm Total length) where males were predominant. Explanation as to why males were only seen in this size class could not be determined from the results of the study.</p>
In Partial fulfillment of the award of a BSc (Hons) degree in Zoology
https://doi.org/10.5281/zenodo.4650053
oai:zenodo.org:4650053
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4650052
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Fish
Lake
Victoria
development
Oocyte
Rastrineobola argentae
Honours
Aspects of the life history of the Silver Cyprinid Rastrineobola argentea (Pelligrin 1904) (Teleostei: Cyprinidae)
info:eu-repo/semantics/other
oai:zenodo.org:4751602
2021-12-31T00:02:06Z
user-cib
Chown, Steven
Marais, Elrike
2014-05-05
<p>Organisms are able to respond to their changing environment, and the extent of the response is thought to depend on the degree of variability and predictability of the environment. Furthermore, the form of this physiological phenotypic plasticity has formed the basis of numerous discussions. However, behavioural regulation of the environment can eliminate the need for physiological alterations and therefore phenotypic plasticity (the Bogert effect). Furthermore, these physiological responses should be investigated in a cost-benefit framework. First, because of the increasing realisation of the importance of cue reliability and variation of the environment for organism response, statistical measures of environmental variability and predictability were investigated. Microclimate temperature data from two localities were used (highly predictably and variable vs. unpredictable and less variable). The proportionate coefficient of variance was most suited to measure variability, whereas Fourier transformation technique seemed to be the most useful estimate of temperature predictability. Acclimation and hardening can often elicit physiological responses that may increase fitness. I investigated life-stage differences in acclimation and hardening ability in the lethal limits and supercooling ability in Paractora dreuxi. The extent of plasticity in both adults and larvae were surprisingly low. The lower lethal limit remained unaffected by acclimation, hardening, and the interaction between acclimation and hardening. However, in the upper lethal limits of adult P. dreuxi a low temperature acclimation significantly increased survival to that of above the warm acclimated individuals. Furthermore, a strong life-stage effect was evident in the supercooling points. While larvae did not show any plasticity, the acclimation*hardening interaction had a significant effect on adults SCP.</p>
Submitted for the Degree of Doctor of Zoology
https://doi.org/10.5281/zenodo.4751602
oai:zenodo.org:4751602
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751601
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
thermal tolerance
insect models
PhD
Thermal tolerance responses to environmental variability in insect models
info:eu-repo/semantics/other
oai:zenodo.org:4675664
2021-12-31T00:02:14Z
openaire_data
user-cib
Michael Somers
Rolanda Julius
2008-05-28
<p>Alien invasive species can potentially alter each and every trophic level of the ecosystem through its action of habitat change. Chromolaena odorata is an aggressive invader that has the widest distribution of all alien invasive plant species within the Hluhluwe- iMfolozi Park. It is known to invade to an impenetrable extent, shading out and competitively excluding large areas of native vegetation. Ant assemblages of intact native vegetation were compared with ant assemblages of vegetation invaded by C. odorata for different time periods and also to ant assemblages in vegetation cleared of C. odorata for different time periods. Results showed species compositional changes and ant faunal abundance declines for habitats with long invasion periods compared with recently invaded and intact habitats. Clearing of C. odorata seemed effective as no difference in ant faunal abundance was found between cleared and intact habitats. The effect and changes associated with C. odorata invasion thus seems to be reversible and native ant faunal assemblages may be restored and likely reflects similar responses of other fauna. Temporal assessment also indicated important differences in long and short term effects of invasion and clearing.</p>
To determine the response of ant communities to Chromolaena odorata and its clearing.
https://doi.org/10.5281/zenodo.4675664
oai:zenodo.org:4675664
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4675663
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Entomology
Honours
The response of native ant communities to an alien invasive species (Chromolaena odorata) - the effect of temporal variation in invasion and clearing
info:eu-repo/semantics/other
oai:zenodo.org:4757132
2021-12-31T00:02:31Z
openaire_data
user-cib
van Rensburg, Berndt
Coetzee, Bernard
2008-06-11
The Important Bird Areas (IBAs) network of BirdLife International aims to identify sites
that are essential for the long-term conservation of the world's avifauna. A number of
global change events have the potential to negatively affect, either directly or indirectly,
most bird species, biodiversity in general and associated ecological processes in these
areas identified as IBAs. To assist conservation decisions, I assessed a suite of ten
landscape scale anthropogenic pressures to 115 Important Bird Areas (IBAs) in South
Africa, both those currently placing pressures on IBAs and those that constitute likely
future vulnerability to transformation. These threats are combined with irreplaceability, a
frequently used measure of conservation importance, to identify the suite of IBAs which
are high priority sites for conservation interventions: those with high irreplaceability and
are highly vulnerable to anthropogenic threats. A total of 22 (19%) of the South African
IBAs are highly irreplaceable and are highly vulnerable to at least some of the pressures
assessed. Afforestation, current and potential future patterns of alien plant invasions
affect the largest number of highly irreplaceable IBAs. Only 9% of the area of highly
irreplaceable IBAs is formally protected. A total of 81 IBAs (71%) are less than 5%
degraded or transformed. This result, together with seven highly irreplaceable IBAs
found outside of formally protected areas with lower human densities than expected by
chance provides an ideal opportunity for conservation interventions. However, all the pressures assessed vary geographically, with no discernible systematic pattern that might
assist conservation managers to design effective regional interventions. Furthermore, I
used the newly emerging technique of ensemble forecasting to assess the impact of
climate change on endemic birds in relation to the IBAs network. I used 50 endemic
species, eight bioclimatic envelope models, four climate change models and two methods
of transformation to presence or absence, which essentially creates 2400 projections for
the years 2070-2100. The consensual projection shows that climate change impacts are
very likely to be severe. The majority of species (62%) lose climatically suitable space
and 99% of grid cells show species turnover. Five species lose at least 85% of
climatically suitable space. The current locations of the South African Important Bird
Areas network is very likely ineffective to conserve endemic birds under climate change
along a "business a usual" emissions scenario. Many IBAs show species loss (41%; 47
IBAs) and species turnover (77%; 95 IBAs). However, an irreplaceability analysis
identified mountainous regions in South Africa as irreplaceable refugia for endemic
species, and some of these regions are existing IBAs. These IBAs should receive renewed
conservation attention, as they have the potential to substantially contribute to a flexible
conservation network under realistic scenarios of climate change. Considering all the
global change threats assessed in this study, the Amersfoort-Bethal-Carolina District and
the Grassland Biosphere Reserve (IBA codes: SA018; SA020) are the key IBAs in South
Africa for conservation prioritisation.
MSc Thesis
https://doi.org/10.5281/zenodo.4757132
oai:zenodo.org:4757132
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4757131
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Geography
Masters
Implications of global change for Important Bird Areas in South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4748427
2021-12-31T00:02:04Z
openaire_data
user-cib
Richardson, Dave
Gibson, Michelle
2012-01-18
My master's research combines aspects of pollination biology and invasion biology to explore the invasive predictors and impacts of a globally invasive group of plants – Australian acacias. Specifically, I investigate the role of reproductive biology in their invasion success (Chapter 2), the impacts of a specific species, Acacia saligna, on native plant-pollinator communities in South Africa (Chapter 3), and if the impact of A. saligna on native plant species can be predicted, based on floral trait similarity (Chapter 4).
Australian acacias possess many floral traits implicated in plant invasion success, including extensive, dense floral displays, prolific seed production, long-lived seed banks, and propensity for vegetative reproduction. In Chapter 2 of my thesis, co-authors and I investigate if such reproductive traits influence whether or not a species becomes invasive once it is introduced by qualitatively and quantitatively analyzing literature and data collected from published and unpublished data. We found that invasive species reach reproductive maturity earlier and are more commonly able to resprout. Our findings have important implications for management of existing Acacia invasions as well as the assessment and prevention of further introductions of Acacia species leading to invasion.
Impacts of invasive plant species on native plant visitation and consequent reproduction are often negative and have important implications for future ecosystem health. Acacia saligna is a problematic woody invasive shrub in many Mediterranean regions, and in South Africa, it invades fynbos vegetation, which boasts one of the highest plant diversities per area in the world as well as many specialized pollination mutualisms. It blooms during the flowering peak of most native species and forms dense, showy floral displays, thus the possibility of pollinator-mediated interactions with co-flowering native species is high. In Chapter 3, I assess the impact of flowering A. saligna on insect visitation to co-flowering native species by conducting flower observations at both an invaded and uninvaded (control) site. One of the native species most-visited by native honeybees, Roepera fulva, had high flower visitor overlap with A. saligna and suffered significantly lower visitation from all insects and from honeybees when A. saligna was present than at the control site. The native honeybee appears to be the most important visitor to A. saligna as it was the most frequent and mobile. Due to its foraging efficiency and dominance in pollinator communities, Apis mellifera subsp. capensis could be an important mediator of the negative effect of A. saligna on co-flowering natives, especially those frequently visited by honeybees.
The use of floral traits as predictors of a species' effect on co-flowering plants via pollination is commonly used in pollination biology. In the fourth chapter of my thesis, I apply the predictive principle of floral traits on flower visitation to see if floral traits can predict the impact of an invasive plant species on co-flowering native species, and if so, which floral traits are the most important. Following the same flower observation protocol as Chapter 3, I compare assess two measures of invasion impact on native flowers – change in visitation rate to native plant species between invaded and uninvaded sites and flower visitor overlap between A. saligna and native species – and test for a correlation with floral trait similarity of native species to and A. saligna. Similarity of categorical traits and all traits combined (categorical and continuous) were significantly positively correlated with flower visitor overlap, indicating that native species with categorical traits similar to A. saligna were more likely to share flower visitors with A. saligna. Floral symmetry and shape similarity were the most important categorical traits in driving flower visitor overlap. Findings suggest an important link between categorical floral traits and ability to predict invasive plant impact on native flower-insect interactions; however, more comprehensive studies are required for conclusive results.
MSc thesis
https://doi.org/10.5281/zenodo.4748427
oai:zenodo.org:4748427
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748426
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
pollination ecology
invasion impacts
flower morphology
plant-pollinator interactions
Australian acacias
Acacia saligna
invasive plants
reproductive biology
pollination syndromes
biological invasions
Masters
Invasive Australian acacias: reproductive biology and effects on native plant-pollinator communities in Cape fynbos
info:eu-repo/semantics/other
oai:zenodo.org:4751598
2021-12-31T00:02:04Z
openaire_data
user-cib
Chown, Steven
Lyons, Candice
2013-07-09
Data collected was for two African malaria vectors, Anopheles arabiensis and Anopheles funestus. It includes information on thermal tolerance variables (CT and LT data) and information on development rate temperature relationships under constant and fluctuating temperatures. Additionally, desiccation tolerance of both species was determined under a range of temperature and humidity treatments. All experiments investigated these parameters for several adult age groups (where applicable) and for both sexes. The influence of acclimation was also investigated in critical thermal limit trials. Thermal tolerance data includes a comparison between wild and laboratory strains of both species. Data were used to construct a simple distribution map of both anophelines under various climate change scenarios, using the software CLIMEX.
The dataset was developed as part of my PhD research with the ultimate aim in developing a bottom up or mechanistic distribution model for both vectors, in the face of changing climates.
https://doi.org/10.5281/zenodo.4751598
oai:zenodo.org:4751598
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751597
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Climate change
malaria
Physiology
PhD
Physiological tolerances and future distributions of two malaria vectors, Anopheles arabiensis and Anopheles funestus
info:eu-repo/semantics/other
oai:zenodo.org:4751628
2021-12-31T00:02:17Z
openaire_data
user-cib
Richardson, Dave
Ruwanza, Sheunesu
2012-10-15
Invasive alien species are widely considered to be the second most significant threat to
biodiversity globally following direct habitat destruction. The invasion of riparian systems
worldwide by alien plants has contributed to profound changes in biodiversity and ecosystem
functioning. In South Africa, river banks and river beds are amongst the most severely
invaded landscapes, with the most damaging invaders, especially in the Fynbos Biome,
being trees and shrubs of the Australian genera Acacia and Eucalyptus. Although large-scale
management operations are underway to clear invasive trees and restore ecosystems, little
is known regarding opportunities and constraints of native species recovery after alien
clearing. The core aim of this thesis is to consider whether key aspects of two widely cited
restoration models (successional and alternative-state models) are useful for guiding
effective management of severely-invaded riparian vegetation. As a study system, I used the
Berg River in the Western Cape, South Africa which is severely impacted by invasive trees,
especially Eucalyptus camaldulensis. By linking the studies of constraints for restoration and
opportunities for native species recovery, the aim was to provide new possibilities for
restoration in riparian zones.
For PhD thesis purpose
https://doi.org/10.5281/zenodo.4751628
oai:zenodo.org:4751628
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751627
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
invasion
Restoration
PhD
Opportunities and constraints in the restoration of riparian ecosystems invaded by alien trees: insights from the Western Cape, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4749262
2021-12-31T00:02:31Z
openaire_data
user-cib
Somers, Michael
Mgobozi, Mandisa
2008-05-06
Biological indicators measure components of the biota and are used to give general information about complex ecosystems in which they occur, playing key roles in conservation planning and management. This study illustrates the impact of habitat change by factors that are extrinsic to the habitats in question and the importance of spider responses in aiding management decisions. The spider responses illustrated existence of environmental change and represent responses of other biota.
The conclusions drawn from this study have important management implications for protected areas with grazing herbivores and occurrence of alien invasive plants. Grazed sites showed the highest abundance, diversity and species richness, while ungrazed had the lowest. The implications from this study are that no grazing has negative implications on lower trophic levels, whereas grazing seems to result in favourable conditions for optimal abundance, diversity and species richness.
The higher abundance, diversity and species richness associated with grazed sites could result from increased ground cover, greater variation in habitat structure, increased plant diversity and enhanced soil/plant nutrient concentrations. But, ungrazed sites in turn become more monotonous and provide less habitat diversity. However, the characteristic species for each grazing intensity level demonstrates the difficulty in making generalizations for management even for closely related species.
The results further opposed the assumption that grazing lawns are a result of overgrazing and thus highly undesirable. This grassland type in comparison to tall bunch grassland displayed the highest spider diversity and species richness. This evidence further supports the conclusion that grazing lawns are steady state communities of their own and not a sub-set of any other grassland type. Therefore, veld management decisions that eradicate grazing lawns are negative for the park as the fauna and flora associated with this grassland type will be lost, leading to cascading effects.
Additionally, this study illustrated that habitat modification by invasion of invasive alien plant species has detrimental consequences for the endemic fauna. C. odorata invasion results in a monotonous habitat structure. Consequently, structural heterogeneity is a primary determinant for spider diversity as opposed to abundance of prey, because plant height and architecture drive spider colonization.
Therefore, removal of alien invasive weeds results in returning a system to close approximation of its condition prior to disturbance with both structure and function recreated. Assemblage patterns can be selected as endpoints to measure the ecological rehabilitation; thus, the non-significant differences in assemblage patterns of the control versus cleared sites imply that the system is rehabilitating with clearing without further management intervention.
This study adds to the limited information on the implications of grazing intensities, grassland types, short and long-term invasion and clearing of an alien invasive plant on spider communities.
https://doi.org/10.5281/zenodo.4749262
oai:zenodo.org:4749262
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4749261
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Zoology
Masters
Spider community responses to Chromolaena odorata invasion, grassland type and grazing intensities
info:eu-repo/semantics/other
oai:zenodo.org:4636291
2021-12-31T00:02:08Z
user-cib
Stefan Foord
Vhuhwavho Gelebe
2013-02-05
<p>Scorpions are an important component of the ground-dwelling invertebrate fauna, and may have value as indicators of ground-dwelling invertebrate diversity. However, some level of understanding of which factors influence patterns of their distribution and diversity is necessary prior to any investigation of their use in conservation planning and as indicators. This project details scorpion diversity patterns in the western Soutpansberg along a north-south altitudinal transect. Scorpions were collected by active searching at all 11 sites along the gradient. A total of 267 scorpions in 16 species, 8 genera and 3 families were recorded. Species distribution was heavily (66 % of variation) affected by soil temperature, proportion of bare ground and rock content of the soil. Species richness peaked at mid-elevations and two endemic taxa were restricted to the mid and higher elevations. Although half the effort was invested in sampling at night, active searching at night was more effective than daytime sampling. This study provides the first quantitative estimate of scorpions along an altitudinal transect in South Africa that could form the basis of a predictive framework for scorpion diversity in the Vhembe region. Keywords: Center of endemism, Scorpiones, mid-domain effect</p>
Baseline scorpion data for altitudinal transect and factors that determine scorpion distribution
https://doi.org/10.5281/zenodo.4636291
oai:zenodo.org:4636291
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4636290
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Center of endemism
Scorpiones
mid-domain effect
Honours
Scorpion diversity along a strong environmental gradient and an evaluation of sampling protocols
info:eu-repo/semantics/other
oai:zenodo.org:4751613
2024-01-25T00:02:00Z
openaire_data
user-cib
Esler, Karen
Nsikani, Mlungele
2019-01-25
A significant proportion of the world's ecosystems are invaded by alien N2-fixing woody species such as Australian acacias. Invasive alien N2-fixing woody species often transform ecosystems through their negative impacts on soil chemistry, seed banks and microbial communities, and native plant diversity. Management interventions such as clearing are necessary to reduce these negative impacts. It is often assumed that clearing the invasive species will lead to a dissipation of their impacts and native plant diversity recovery. However, this is often not the case because the invasive species' negative impacts can become persistent soil legacy effects and present barriers to restoration of viable native plant communities. Understanding barriers to restoration can lead to improved restoration outcomes. Using Acacia saligna invasions in the South African fynbos as case study, this thesis explored soil legacy effects, secondary invasion and weedy native species dominance after clearing invasive acacias.
In chapter one, I reviewed global literature to understand how soil legacy effects of invasive alien N2-fixing woody species present barriers to restoration, and identify management actions that could potentially be used to address them. In chapter two, I investigated how long soil legacy effects of invasive A. saligna persist after clearing using soil sample analyses. In chapter three, I explored the effect of invasive A. saligna's soil chemical and biotic legacies, and weedy native species on native species re-establishment using a greenhouse experiment. In chapter four, I identified species that are secondary invaders after clearing invasive A. saligna across several sites and investigated the effects of vegetation type and fire application on their establishment over three years after clearing using vegetation monitoring. In chapter five, I investigated interactions between secondary invaders and the extent to which soil nitrate levels, apparent after clearing invasive A. saligna, influence secondary invasion and weedy native species dominance using growth chamber and greenhouse experiments.
I found that altered soil microbial communities, depleted native soil seed banks, elevated N status, secondary invasion and weedy native species dominance, and reinvasion can be barriers to restoration. Furthermore, management actions such as carbon addition, soil microbial treatments, herbicide or graminicide application and native species reintroduction can be used to address these barriers to restoration. Acacia saligna's soil chemical legacies persisted up to ten years after clearing. However, they did not have direct negative consequences on the re-establishment of native proteoid shrubs but soil biotic legacies and presence of weedy native species reduced their growth. Secondary invasion was not habitat specific, was promoted by fire application and persisted up to three years after clearing at levels similar to or higher than the first year. Lastly, growth of secondary invaders and weedy native species increased with an increase in soil nitrate levels.
I conclude that practicing restoration ecologists should manage soil legacy effects, secondary invaders and weedy native species after clearing invasive A. saligna to improve restoration outcomes.
To get a PhD
https://doi.org/10.5281/zenodo.4751613
oai:zenodo.org:4751613
eng
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https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751612
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Fynbos
Invasive acacias
Secondary invader
Soil legacy effects
Restoration
PhD
Barriers to ecosystem restoration after clearing invasive Acacia species in the South African fynbos: soil legacy effects, secondary invaders and weedy native species
info:eu-repo/semantics/other
oai:zenodo.org:4751949
2021-05-13T01:48:15Z
openaire_data
user-cib
Esler, Karen
Zylstra, Matthew
2014-04-01
This study brings together four core themes: connectedness with nature (CWN), invasive alien species (IAS), and education for sustainability (EfS); each of which are
explored around - and in relationship to - the core concept of meaningful nature experience (MNE). Using qualitative and quantitative (mixed) methods, the study found that MNE is commonly associated CWN and can be a catalyst, motivation and predictor for environmentally responsible
behaviour. MNEs were also considered highly influential in shaping respondents life outlook. Respondents who have had a MNE exhibit a higher CWN; a positive correlation
exists between frequency of MNE (fMNE) and CWN. The presence of IAS in a landscape is likely to adversely affect MNE for stated reasons of ecological impacts, diminished 'naturalness' , destructiveness and reduced diversity. Those viewing IAS as potentially enhancing their MNEs cite reasons of beauty, novelty and enjoyment. Respondents CWN does not appear to affect perceptions of IAS; however, elevated CWN may invoke empathy, a sense of relatedness and appreciation of their intrinsic value as 'life'. IAS may also feature in MNEs and, through experiential and metaphorical insight, can deliver newfound understandings of social and ecological connections as they relate to IAS. Overall research outcomes support an educational revitalization that incorporates appreciations of MNE, CWN and their potentials to cultivate an ecological consciousness.
Humanity's growing separation from nature is central to
the social-ecological crises facing earth. The prime purpose of this transdisciplinary research was to therefore explore the potential for meaningful nature experience (MNE) to mitigate modern society's fading connectedness with nature(CWN). In assessing the potential impacts of loss of biodiversity on human experience, the study was also purposed to identify the ways that invasive alien species(IAS) may affect current and future MNE. The research additionally considered how an individual's CWN may affect perceptions toward IAS. The overall intent of this research was to determine how insights from the above may
enhance conservation and sustainability education.
https://doi.org/10.5281/zenodo.4751949
oai:zenodo.org:4751949
eng
Zenodo
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https://doi.org/10.5281/zenodo.4751948
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Nature Experiences
Perceptions
Surveys (Likert-scale)
Interview Transcripts
Phenomenological Descriptions
Mixed Methods
PhD
Exploring meaningful nature experience, connectedness with nature and the revitalization of transformative education for sustainability
info:eu-repo/semantics/other
oai:zenodo.org:4573361
2021-12-31T00:02:28Z
openaire_data
user-cib
Mirijam Gaertner
Nombuso P. Ngubane
2014-02-03
<p>Dataset of stack burning data collected at the Blaawuberg Nature Reserve and Glencairn residential area under the manamgenent of the City of Cape Town</p>
To investigate the impact of stack burning of invasive alien species, Acacia saligna, on both native and alien vegetation.
https://doi.org/10.5281/zenodo.4573361
oai:zenodo.org:4573361
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4573360
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stack burning
Acacia saligna
burn scars
fynbos
Honours
Management consequences after stack burning of invasive alien species (Acacia saligna)
info:eu-repo/semantics/other
oai:zenodo.org:4616775
2021-12-31T00:02:22Z
openaire_data
user-cib
Eileen Campbell
Devon Larkin
2015-03-21
<p>There have been very few studies on the impacts of Acacia melanoxylon on the environmental conditions in forest communities in South Africa. The aim of this study was to determine the effects of this exotic species on the environmental conditions within forest communities in Harkerville forest, located between Knysna and Plettenberg Bay in South Africa. The effects on the nutrient, moisture and organic content of the soil were studied, as well as the effects on canopy closure and the light penetration to the forest floor. In addition, potential sources of invasion were also identified in the area. It was determined that blackwood did not influence the moisture and organic matter content of the soil, it did however affect the phosphorus and ammonia content. Phosphorus was found to be significantly lower in the vicinity of the blackwood trees. The soil nitrate concentration was significantly higher. Canopy closure was significantly reduced in the invaded areas, which had resulted in a significant increase in light penetration to the forest floor. This was attributed to blackwood's preference for open areas. Major sources of blackwood seed identified in the area, were a very dense stand of blackwood on private land and blackwood plantations in the area. The phytosociology was determined not to be different between the invaded and non-invaded. The study determined that the blackwood altered the tree layer by reducing the number of tree species that comprise the layer. It was concluded that blackwood had minimal impact of the on the environmental conditions measured. Even though the differences in the environmental conditions measured were significant, they were slight. The major issue identified was the dispersal of seeds from nearby sources . Fortunately the seeds do not germinate readily under the closed canopies in the forest. Management and monitoring of blackwood trees is prominent in the area, the adult blackwood trees are ring-barked and the seedlings removed within the vicinity of water courses.</p>
Submitted in partial fulfilment of the requirements of the degree of BACCALAUREUS SCIENTIAE HONORES Faculty of Science, Nelson Mandela Metropolitan University, Port Elizabeth
https://doi.org/10.5281/zenodo.4616775
oai:zenodo.org:4616775
eng
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https://doi.org/10.5281/zenodo.4616774
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Acacia melanoxylon
Blackwood
phytosociology
Harkerville forest
Honours
Impacts of Acacia melanoxylon R.Br. (blackwood) on the environmental conditions and phytosociology in forest communities in Harkerville forest, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4761507
2021-12-31T00:02:04Z
openaire_data
user-cib
McGeoch, Melodie
Spear, Dian
Marais, Elrike
2012-03-07
<p>See McGeoch et al. 2010. Data availability is based on information from national reports and Pyšek et al. 2008.</p>
https://doi.org/10.5281/zenodo.4761507
oai:zenodo.org:4761507
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761506
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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Post-doc
A measure of data availability on alien species for countries globally
info:eu-repo/semantics/other
oai:zenodo.org:4751626
2021-12-31T00:02:21Z
user-cib
Johnson, Steven
Rodger, James
2013-10-11
Plants that can self-fertilise should, on average, be more invasive than plants that can not self-fertilise because they can reproduce regardless of the availability of mates and pollinators. Self-fertilisation should have a strong effect on invasiveness because, to become invasive, introduced plants have to pass through bottlenecks of low plant abundance when mates and pollinators are likely to be scarce. Under these conditions, reproduction of plants that can not self-fertilise is often limited by pollen receipt. Selfing may thus contribute to invasiveness by alleviating pollen limitation Allee effects (pollen limitation caused by low abundance) especially as theoretical work indicates that ability to invade and rate of invasion are highly sensitive to fecundity of small and isolated populations and single individuals.
Recently, a correlation between ability to self-fertilise and invasiveness has been observed in several invasive floras, consistent with the hypothesis that species that can self-fertilise should be more invasive. However, it has not yet been demonstrated that this relationship arises from reproductive assurance. To establish the causal basis of a correlation between a plant trait and invasiveness, a mechanism linking that trait to invasiveness must be demonstrated. For this it is necessary to show firstly that the trait actually affects performance in the introduced range and secondly that plant performance affects invasiveness. Self-fertilisation is hypothesised to increase invasiveness by enhancing reproductive performance. The first step in testing this hypothesis is therefore to show that being able to self-fertilise increases fecundity, i.e. that it provides reproductive assurance. However, progeny from self-fertilisation often suffer from inbreeding depression – they perform worse than those from cross-fertilisation – so it is also necessary to show that this cost does not outweigh the reproductive assurance benefit of selfing. So far, reproductive assurance has been assessed in only a few invasive plant species. These studies did not assess inbreeding depression and only one investigated reproductive assurance in relation to abundance, finding no relationship.
In this thesis I have sought to understand the importance of self-fertilisation for reproduction of invasive plants in the introduced range through case studies. In particular, I assessed whether reproductive assurance from self-fertilization alleviates Allee effects via pollen limitation. To do this I tested whether pollen limitation and reproductive assurance were greater at low plant abundance. Further, I conducted progeny trials to assess inbreeding depression, as this cost of selfing potentially negates reproductive assurance benefits. I also conducted observations and experiments to identify the principle pollinators of my study species as reproductive assurance and its relationship to plant abundance depend on pollinator visitation,
The Australian trees Acacia mearnsii and A. dealbata are highly invasive in the study region of KwaZulu-Natal, South Africa. Through controlled pollination experiments I established that A. dealbata was self-compatible and autonomously self-fertilising, while previous studies reported A. mearnsii as self-incompatible. I identified the native honeybee Apis mellifera scutellata as the principal pollinator of A. mearnsii, A. dealbata and a co-occuring related invasive species, Acacia decurrens, in the study region. I conducted pollen supplementation experiments in two of these species, aiming to indirectly assess reproductive assurance from selfing in the self-compatible A. dealbata by comparing pollen limitation between this species and the self-incompatible A. mearnsii. In both species, I conducted pollen supplementation in single isolated trees and trees in continuous populations, to test whether pollen limitation was more severe in isolation. These pollen supplementation experiments were inconclusive with respect to pollen limitation but indicated that if there was pollen limitation in A. mearnsii, it was not related to isolation. Progeny trials in A. dealbata revealed relatively strong inbreeding depression in progeny growth and survival. This suggests that selfed progeny may not reach reproduction, so even if self-fertilisation provides reproductive assurance, it may not contribute to invasion in this species.
As floral morphology of Acacia species prohibits the use of emasculation experiments to directly measure reproductive assurance, I conducted further investigations on Lilium formosanum, a large-flowered, autonomously self-pollinating invasive geophyte native to Taiwan. I identified the long tongued hawkmoth Agrius convolvuli as its primary pollinator in its introduced range in KwaZulu-Natal, South Africa. Trials of progeny from self- and cross-pollination in the field (to 31 months) and in a controlled shade-house environment (to 26 months) showed no evidence of inbreeding depression in germination, growth or survival. Flowering was assessed in the shade-house as most plants did not flower in the field. Only one of five populations showed inbreeding depression in probability of flowering in the second year of growth but none showed inbreeding depression in the third year. Inbreeding depression was thus generally undetectable in L. formosanum.
I tested for reproductive assurance and pollen limitation in L. formosanum by conducting floral emasculations and pollen supplementations in multiple populations across a range of population size and isolation in three different years. These experiments demonstrated that reproductive assurance was substantial and that pollen limitation was low or absent. Contrary to expectations, reproductive assurance was not greater in smaller populations and was greater for more isolated populations in only one of three years. However, that study did not include many very small populations. To assess reproductive assurance at very low abundance, I created arrays of emasculated and intact plants within and around naturally occurring populations at two sites. Isolated plants had higher reproductive assurance than did plants placed inside the continuous population at one site, supporting the hypothesis that selfing provides reproductive assurance against pollen-limitation Allee effects. However, in these studies, generally inadequate pollinator visitation was the main reason that L. formosanum exhibited reproductive assurance through selfing.
The substantial reproductive assurance and minimal inbreeding depression displayed by L. formosanum makes a compelling case for the hypothesis that self-pollination promotes invasion. Nevertheless, demographic modelling will be necessary to assess whether increased fecundity through reproductive assurance results in increased rates of population growth and spread, and hence invasion, in this species. To assess whether reproductive assurance accounts for the relationship between ability to self-fertilise and invasiveness in plants generally, the contribution of self-fertilisation to invasiveness will have to be evaluated for a larger sample of invasive and non-invasive introduced species, using the approaches taken in this thesis, followed up by demographic modelling.
The data described in this thesis were collected in the Republic of South Africa from June 2003 to October 2011. Experimental work was carried out while registered at the School of Biological and Conservation Sciences, University of KwaZulu-Natal, Pietermaritzburg, under the supervision of Professor Steven D. Johnson and co-supervision of Professor Mark van Kleunen.
This thesis, submitted for the degree of Doctor of Philosophy in the Faculty of Science and
Agriculture, University of KwaZulu-Natal, Pietermaritzburg, represents original work by the author and has not otherwise been submitted in any form for any degree or diploma to any university. Where use has been made of the work of others, it is duly acknowledged in the text.
https://doi.org/10.5281/zenodo.4751626
oai:zenodo.org:4751626
eng
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https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751625
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pollination
Allee effects
breeding system
inbreeding depression
pollinators
Lilium formosanum
Acacia dealbata
Acacia mearnsii
PhD
Consequences of self-fertilisation for fecundity and progency performance in invasive plants
info:eu-repo/semantics/other
oai:zenodo.org:4751608
2021-05-12T15:02:20Z
user-cib
Chown, Steven
McClelland, Gregory
2019-06-14
info:eu-repo/date/embargoEnd/2024-06-14
As the pace of climate change has begun to accelerate so too has it become clear that the
direct impacts thereof are likely to have profound consequences for many island systems.
Moreover, it has also been suggested that climate change will exacerbate the effects of
many invasive species, so further impacting both diversity and ecosystem functioning.
Forecasts for such interactions have been most pronounced for the Southern Ocean islands,
which are home to a wide variety of endemic species. This thesis is about such interactions
and their specific impacts on a key endemic, the black-faced sheathbill (Chionis minor) on
the Prince Edward Islands.
Of increasing concern is how invasive rodent populations in the Southern Ocean may
be responding to global climate change, as ameliorating conditions on these islands are
forecast to decrease thermal and resource restrictions on rodents. However, firm evidence
for changing rodent populations in response to climate change, and demonstrations of
associated impacts on the terrestrial environment, are entirely absent for the region. In
Chapter 2 of this thesis, these relationships are explored for invasive house mice (Mus
musculus) on Marion Island. Using spatially explicit capture-recapture modeling, it is
determined that mouse populations across a range of habitats have increased over time.
Owing to an extended breeding season, made possible by ameliorating conditions brought
on by climate change, the total number of mice on the island at annual peak density more
than doubled over the past decade. It is also demonstrated that mice directly reduce
invertebrate densities, with biomass losses up to two orders of magnitude in some habitats.
Because of the importance of invertebrates to nutrient cycling on the island, such changes
are likely to have significant ecosystem-level impacts.
Submitted in partial fulfilment for the degree Doctor of Philosophy in Zoology
https://doi.org/10.5281/zenodo.4751608
oai:zenodo.org:4751608
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751607
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Black-faced Sheathbill
Marion Island
PhD
Ecology of the Black-faced Sheathbill on Marion Island
info:eu-repo/semantics/other
oai:zenodo.org:4740283
2021-12-31T00:02:16Z
user-cib
Chown, Steven
Mukhadi, Fulufhelo Licken
2014-04-24
Species' seasonal behaviour is of paramount importance in understanding community functioning
and dynamics. Recently, plant phenology has further gained significance as a reliable indicator of
climate change impacts. Despite the importance of understanding plant dynamics, there are
relatively few plant phenological records for the sub-Antarctic region, and where records exist they
are often not extensive. Sub-Antarctic Marion Island, typical of Southern Ocean Islands, offers a
useful setting for addressing these knowledge gaps. This study documented the vegetative and
reproductive phenologies (or aggregate phenological patterns) of twelve indigenous and three alien
vascular plant species on the island. The phenological differences among the species and distinct
seasonal groupings (e.g. early, intermediate and late species) were examined. I also investigated the
phenological differences among the indigenous and alien plant species. Furthermore, the onset of
selected reproductive phenophases from the current records was compared with historical records
for determining the extent of climate change-related alterations in phenology. Phenological data
were collected fortnightly on five, 5 m x 5 m permanent plots per species (except for a few species)
for a full growing season. Thus the sample size is n = 5 for all plant species except for Crassula
moschata (n = 4), Juncus effusus (n=4) and Rumex acetosella (n=1). Sites of the same species were
separated by at least 500 m except for the alien plant, Juncus effusus, where all four known
populations were selected despite two of these populations being < 500 m apart. This study
indicated that Marion Island plants grow throughout the year with no major peaks except in
Azorella selago and Acaena magellanica which showed winter dormancy. However, reproduction
in most plant species predominately occurred in spring and summer months. Pringlea
antiscorbutica and Poa cookii were the first two species to set flower buds in September while most
species dispersed their seeds in summer except for Agrostis magellanica and Crassula moschata
which dispersed in early autumn. Distinct from most temperate systems, the reproductive
seasonality displayed by Marion Island plant species is explained more by daylength than by
temperature, perhaps due to the region's typical thermal aseasonality. Interestingly, many cooccurring
species and/or clades across the Falkland, Kerguelen, Macquarie and South Georgia
Islands also showed similar flowering onset date to the Marion Island plants, further confirming
their daylength sensitivity. However...
Submitted in partial fulfillment of the requirements for the degree of Master of
Science (Botany)
https://doi.org/10.5281/zenodo.4740283
oai:zenodo.org:4740283
eng
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https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740282
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indigenous
alien
vascular flowering plants
Marion Island
Masters
Phenology of indigenous and alien vascular flowering plants on sub-Antarctic Marion Island
info:eu-repo/semantics/other
oai:zenodo.org:4757028
2021-12-31T00:02:03Z
openaire_data
user-cib
Chown, Steven
Coetzee, Bernard
2013-08-15
The challenge of conserving biodiversity is daunting. Despite some local conservation gains,
most indicators of the condition of global biodiversity show declines since the 1970's, while
indicators of the threats to biodiversity all show increases. Humanity has in part responded
to the global biodiversity extinction crisis by establishing protected areas (PA) and they are
widely considered cornerstones of conservation.
However, their efficacy in maintaining biodiversity is much debated. Previous studies have
been unable to provide a general answer because of their typically restricted geographic
and/or taxonomic focus, or qualitative approach. Using a global meta-analysis with 861 pairwise
comparisons inside and outside PAs from 86 studies across five major taxon groups, I
tested the hypothesis that PAs achieve significant conservation outcomes measured as
higher biodiversity values compared with alternative land covers. I found that globally, PAs
typically contain higher abundances of individual species, higher assemblage abundances
and higher species richness. Variation in effect sizes among taxa nonetheless underscores
that PA efficacy can be context specific.
To examine factors driving the context specific nature of PA efficacy, an exact distance,
timed point count methodology was used to assess PAs ecological effectiveness in terms of
bird assemblages of the Kruger National Park (KNP), South Africa, in the Phalaborwa section.
Bird assemblages inside the KNP were compared to matched sites in rural and urban land
cover, as well as the connecting habitat matrix outside the KNP. Species richness and
abundance were significantly lower inside the KNP compared to other land covers. However,
the species assemblages are markedly different. The artificial addition of resources in an
otherwise resources poor area, mainly in terms of gardening, provide suitable habitat for a
range of species, consistent with the more individuals hypothesis. Large-bodied and ground
nesting species are virtually absent outside the KNP. Thus species richness and abundance
differences between land cover regions mask insidious changes in species traits.
Nonetheless, not formally protected land can contribute positively to the regional
biodiversity portfolio.
Since an understanding of the mechanisms that structure species assemblages can aid in the
consequences of anthropogenic drivers disentangling them, I describe and analyse the body size frequency distributions (BSFDs) of avian assemblages at several spatial scales in the Afrotropical biogeographic realm. I found that the African avifaunal continental BSFD is
unimodal and right-skewed. African avifaunal BSFDs are quantitatively dissimilar to the
African mammal BSFDs, which are bimodal at all spatial scales. Much of the change in
median body size with spatial scale can be captured by a range-weighted null model,
suggesting that differential turnover between smaller- and larger-bodied species might
explain the shift in the central tendency of the BSFD.
My results for the first time quantitatively demonstrate that PAs are a vital component of a
global biodiversity conservation strategy. However, I also show that PA ecological
effectiveness can be context specific, and understanding which species traits are at risk outside of PAs is critical to predicting their efficacy.
For PhD degree, to assess aims detailed in Abstract above.
https://doi.org/10.5281/zenodo.4757028
oai:zenodo.org:4757028
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4757027
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PhD
Species assembly patterns and protected area effectiveness in times of change: a focus on African avifauna
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oai:zenodo.org:4761484
2021-05-14T13:48:13Z
openaire_data
user-cib
McGeoch, Melodie
Kalwij, Jesse
2008-07-04
Transect level data belonging to Kalwij et al. 2008. This dataset contains the Braun-Blanquet cover estimation of the 720 transects and their environmental data
This dataset was used to conduct the CCA analysis at the transect level of Kalwij et al 2008
https://doi.org/10.5281/zenodo.4761484
oai:zenodo.org:4761484
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761483
info:eu-repo/semantics/restrictedAccess
Botany
Post-doc
Karoo road verge study: Transect level sample data
info:eu-repo/semantics/other
oai:zenodo.org:4772734
2021-05-20T13:48:12Z
openaire_data
user-cib
Chown, Steven
du Plessis, Dorette
2014-09-26
The Iimbovane Outreach Project investigates the abundance and diversity of ants along two extensive transects through the Fynbos and Succulent Karoo biomes of South Africa. It is a long term project initiated in 2005 by Principal Investigator Prof. S.L. Chown, Stellenbosch University. Data collection is carried out by learners on a biannual (spring and autumn) basis in collaboration.
To provide information on the location and history of Iimbovane long-term monitoring research sites.
https://doi.org/10.5281/zenodo.4772734
oai:zenodo.org:4772734
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4772733
info:eu-repo/semantics/restrictedAccess
biodiversity
Fynbos
geography
invertebrate diversity
species richness
ants
Longterm Data
Iimbovane Outreach Project: Geospatial Information File
info:eu-repo/semantics/other
oai:zenodo.org:4636833
2021-12-31T00:02:18Z
user-cib
Cang Hui
Hlpheka Evans Chauke
2012-01-23
<p>In this paper we describe the coevolution of phenotypes in a community of predators and of prey using adaptive dynamics. Evolutionary cycling can be one of the outcome of the process. The Models on which the description is based are formed from microscopic stochastic birth and death events, together with a process of random mutation. Births and deaths, can occur as a results of phenotype-dependent interactions between predator and prey individuals and therefore natural selection can be generated. We demonstrate three outcomes of evolution in this paper. A community may evolve to a state at which the predator becomes extinct, or to one at which the species coexist with constant phenotypic values, or the species may coexist with cyclic changes in phenotypic values. The last outcome corresponds to a Red Queen dynamic, in which the selection pressures arising from the predator-prey interaction cause the species to evolve without ever reaching an equilibrium phenotypic state. The Red Queen dynamic will require an intermediate harvesting effciency of the prey by the predator and suffciently high evolutionary rate constant of the prey, and is complex when the model is made stochastic and phenotypically polymorphic. A cyclic outcome lies outside the contemporary focus on evolutionary equilibria, and argues for an extension to a dynamical framework for describing the asymptotic states of evolution.</p>
https://doi.org/10.5281/zenodo.4636833
oai:zenodo.org:4636833
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4636832
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Red Queen
adaptive dynamics
Honours
Capturing the Red Queen using Adaptive Dynamics in a predator-prey coevolution
info:eu-repo/semantics/other
oai:zenodo.org:4761517
2021-12-31T00:02:14Z
openaire_data
user-cib
McGeoch, Melodie
Spear, Dian
2012-03-07
Red-listed species impacted by aliens in South Africa. Numbers of species impacted by aliens and numbers of species that are impacted by aliens that have changed risk categories between consecutive assessments.
https://doi.org/10.5281/zenodo.4761517
oai:zenodo.org:4761517
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761516
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Post-doc
Red-listed species impacted by aliens in South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4650096
2021-12-31T00:02:29Z
user-cib
Augustine Niba
Nobubele Boniwe
2010-11-26
<p>Abstract This study investigated the vertical distribution and temporal changes of limpet species. Species diversity was measured in terms of number of limpet species. Sampling was conducted at Dwesa-Cwebe Nature Reserve and two sites with approximately 1.5 km apart were selected. In each site, three rock pools were chosen: MLWS (mid low water shore), MHWS (mid high water shore) and HWS (high water shore). ANOVA results revealed that no significant differences on species diversity, implying the importance of biological processes such as recruitment rather than physical processes. Despite seasonal differences in environmental conditions, the limpet species occurred across the three shore heights. Although there were significant differences in mean sizes (shell lengths) in three (Cellana capensis, Siphonaria serrata Helcion concolor) out of seven limpet species found, there were significant interaction of season and site, indicating that the mean shell length had significant effects in some seasons but not others. Where there were significant differences, mean shell lengths decreased with a decrease in shore height and vice versa. Mean temperatures and salinities increased significantly with an increase in height. They also showed significant differences among seasons and between sites, suggesting temporal and spatial variations on small scales (1.5 km).</p>
In partial fulfilment of the award of a BSc Honours degree in Zoology
https://doi.org/10.5281/zenodo.4650096
oai:zenodo.org:4650096
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4650095
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Limpets
intertidal zone
rock pools
distribution
species diversity
size
Honours
Patterns of vertical distribution and temporal changes of rockyshore intertidal limpets in rock pools at Dwesa-Cwebe Nature Reserve
info:eu-repo/semantics/other
oai:zenodo.org:4636685
2021-12-31T00:02:28Z
user-cib
Stefan Foord
Nkhangweleni Duncan Nengwenani
2012-03-01
<p>2010 was the "International year of Biodiversity" and was especially important within the Vhembe biosphere reserve of Limpopo province. This initiative was led by the secretariat of the CBD and UNESCO. It was aimed at disseminating information about biodiversity and improving the identification and monitoring of that biodiversity. The present project adapted a method developed for the Iimbovane outreach project to a school in Vuwani, where a citizen science initiative was used to conduct a biodiversity outreach program while simultaneously collecting ant species richness data. The aims of the project were (i) to inventory ant species from Mugoidwa secondary school, (ii) to investigate how species composition from an un-impacted site compared with species from an impacted site over a 12 month period and (iii) to test the effectiveness of the citizen science initiative in promoting biodiversity awareness and understanding. The pitfall method was used to sample ants in an impacted and un-impacted site of the school ground for a year. Grade 11 learners were taught how to sample ants, wash and sort pitfalls and how to use an identification key. Learners were also given lessons in biodiversity. At the end of the project the learners from Mugoidwa secondary school participated in a survey questionnaire along with two other schools. A total of 10577 ants comprising 45 species, 21 genera and 6 subfamilies were identified for study the site. Species composition of the impacted site differed from the un-impacted site. Abundances were also different with the impacted site having higher abundances than the un-impacted site. Each site had species that were unique to them with some species that only occurred on one site contributing to dissimilarities between the sites. Learners successfully participated in the project as citizen scientists and reduced the researcher's workload. Language turned out to be an obstacle in the survey as learners struggled to answer open ended questions.</p>
To inventory the ant species at a secondary school in the rural village of Vuwani, to (ii) investigate how assemblages from an impacted site and an un-impacted site compared throughout the course of a year, and to (iii) investigate the effectiveness of the citizen-science initiative in promoting biodiversity awareness to the learners, evaluating whether learners gain a better appreciation for biodiversity and science in general. The project also aimed to partly address South Africa's obligations to the CBD and the aims of UNSECO within the Vhembe biosphere reserve.
https://doi.org/10.5281/zenodo.4636685
oai:zenodo.org:4636685
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4636684
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Biodiversity
citizen science initiative
Vhembe biosphere reserve
identification and monitoring
public education and awareness
Convention on biological diversity
Honours
Comparative ant phenology and biodiversity awareness at a secondary school in Vuwani
info:eu-repo/semantics/other
oai:zenodo.org:4740258
2021-12-31T00:02:18Z
user-cib
Esler, Karen
Barrow, Stuart
2015-02-10
The number of introductions of alien species is on the rise globally. The resulting impacts on the invaded environments are diverse and often contrasting. Many deliberately introduced species have positive social and economic impacts as people use them to achieve a goal. These goals can be recreational, such as mountain biking in a plantation of alien trees or commercial such as harvesting alien trees for timber. Conflict often arises when the goals of the individuals using the alien species clash with the goals of those trying to mitigate negative impacts of the introductions. As many scientists are more inclined to favour native over alien species, the negative impacts of alien species are better documented in scientific literature. It is valuable to document contrasting impacts of alien species so that they may be managed in a way which does not cause unnecessary conflict. This thesis documents contrasting impacts of Micropterus dolomieu (smallmouth bass) within the Cape Floristic Region (CFR). It does this using the Rondegat River in the Olifants-Doring River system and the Clanwilliam Dam, in the same system, as case studies. Smallmouth bass, Micropterus dolomieu, were removed from the Rondegat River using a piscicide called rotenone by the Western Cape nature conservation authorities; CapeNature. This thesis documents the results of snorkel observations and underwater filming of the river. Native fish densities increased from 0.29 fish/100m2 to 11.81 fish/100m2 following smallmouth bass removal. Documenting the recovery of the native fish population following smallmouth bass removal provides further insight into the negative ecological impacts of the species. The results of the monitoring show that smallmouth bass had extirpated three native species from the invaded reaches and was preying heavily upon juveniles that were dispersing downstream. The removal of the smallmouth bass from the Rondegat River was a project which cost CapeNature both money and time. Through personal communication with implementers of the project and through access to CapeNature financial records, this thesis documents the costs of the Rondegat River smallmouth bass eradication project. It cost CapeNature R 358 068 per kilometre of river to eradicate smallmouth bass from the Rondegat. An estimated 5079 man hours were spent on the final planning and implementing of the two rotenone treatments. These costs represent a negative economic impact of smallmouth bass and are useful in estimating the costs of future eradication projects. These two negative impacts are contrasted with the positive socio-economic impacts of the species. The Clanwilliam Dam, further downstream, hosts a large smallmouth bass population and is considered to be one of South Africa's premier smallmouth bass fishing destinations. Anglers who travel to the dam in order to catch smallmouth bass often spend money at local businesses, thus contributing to the local economy. This expenditure is a positive economic impact of smallmouth bass. Anglers were interviewed at the dam and it was estimated that they spend R2 000 721.61 in the town of Clanwilliam every year. This is taken as the economic impact of smallmouth bass angling upon the town. This expenditure has a positive impact on local businesses and their employees. Smallmouth bass therefore, have contrasting impacts within the CFR and it is important that they are all considered in the management of the species. The Rondegat River smallmouth bass eradication project is an example of how the negative impacts of smallmouth bass can be mitigated without affecting its positive impacts and is a case study that could potentially inform how management of the genus proceeds in South Africa.
MSc thesis
https://doi.org/10.5281/zenodo.4740258
oai:zenodo.org:4740258
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740257
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Alien species
invasion
impacts
economic impact
conflict
rotenone
Masters
Contrasting impact of alien invasive sport fish in the Cape Floristic Region: a focus on Micropterus dolomieu
info:eu-repo/semantics/other
oai:zenodo.org:4636367
2021-12-31T00:02:20Z
user-cib
Stefan Foord
Rifilwe Victor Modiba
2012-03-28
<p>Department of Water Affairs has been removing invasive alien riparian trees along the riparian zones through Working for Water programme since 1995. In this study we assess the progress of the programme by studying the response of benthic macroinvertebrates and adult odonata to alien invasive clearing. We tested if clearing affected the SASS, DBI, ASPT and adult odonata species richness. The study area is in the upper reaches of the Luvuvhu river catchment in Limpopo province (South Africa). A total of 46 invertebrates families were sampled at total of 13 sampling units. The results suggest that clearing has a positive impact on benthic macroinvertebrates with all metrics increasing with an increase in number of times cleared, although the only result that was significant was that of ASPT. The adult Odonata metrics were negatively impacted by clearing and positively by increased canopy and alien cover. These results should however be viewed as preliminary as only one correlation, the positive impact of clearing on ASPT scores, was significant (F2, 10= 0.53, p= 0.6). Seventeen adult Odonata species were recorded from natural, alien and cleared sites. The objective of the study is to test whether clearing intensity of invasive alien plants cover affects SASS, DBI, ASTP, Odonata species richness, and to collect a reference collection of adult Odonata species.</p>
To test whether clearing intensity of invasive alien plants cover affects SASS, DBI and ASTP. To test whether clearing intensity of invasive alien plants affects odonata species richness. To collect a reference collection of adult odonata
https://doi.org/10.5281/zenodo.4636367
oai:zenodo.org:4636367
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4636366
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Invasive alien trees
South African Scoring System Version 5 (SASS5)
benthic macroinvertebrates
Dragonfly biotic index (DBI)
Average Score Per Taxon (ASPT)
Honours
The response of benthic macroinvertebrates and adult Odonata to alien invasive clearing
info:eu-repo/semantics/other
oai:zenodo.org:4751646
2021-12-31T00:02:22Z
openaire_data
user-cib
Chown, Steven
Treasure, Ann
2012-02-01
Climate change and biological invasions are major threats to biodiversity. In particular, these threats are predicted to influence terrestrial systems in the sub-Antarctic, where significant ecosystem responses to both have already been seen. In this thesis, the
sub-Antarctic Prince Edward Island group is used as a model system in which to investigate key questions relating to climate change and invasive species impacts. The island group comprises two islands, Marion (MI) and Prince Edward (PEI), both of which are experiencing rapid warming, yet have different invasive assemblages and in consequence are experiencing different impacts.
Variation in the patterns of invasive species richness and abundance and their underlying causes are matters of considerable ecological and conservation significance. While an increase in thermal energy availability typically results in an increase in species richness, the mechanisms underlying these patterns are poorly understood. In Chapter 2 of this thesis, these relationships are explored for springtails, an important component of the soil fauna on Marion Island. Energy explains a large amount of the spatial variation in indigenous and invasive springtail species richness. Disturbance thresholds and stressful temperatures are more important than increased population sizes in determining this variation in species richness. As both indigenous and invasive springtail species richness and abundance are strongly related to temperature, a warming climate could have
far-reaching consequences for these organisms. In particular, invasive species are predicted to be at an advantage relative to indigenous species under warming conditions.
One species where this seems especially likely, given its physiological responses to experimental warming and drying, is the large invasive tomocerid, Pogonognathellus flavescens. Determining whether this will be the case depends on understanding the factors underlying its range limits and abundance structure. Moreover, few studies have sought to distinguish the causal basis of abundance structure and range limits, particularly for invasive species. Thus, in Chapter 3, local microclimate variables and physiological tolerances of the invasive springtail, P. flavescens (a habitat generalist), are examined. The results suggest that the species should be widely distributed across a range of habitats on MI. However, the springtail is restricted to indigenous Poa cookii tussock grassland habitats in the southeast. The current range limits are set by dispersal limitation (i.e. contingent absences) whilst abundance structure is a function of variation in soil substrate quality. However, over time, the widening distribution of P. cookii, as a consequence of a major management intervention (the eradication of feral cats), may enable P. flavescens to colonise all suitable areas.
In Chapter 4, the focus changes to what has been considered the third major response to climate change, along with range and phenological responses - changing animal body sizes. Body size is one of the most significant and obvious features of animals and is of considerable ecological and physiological importance. A prediction of the temperature-size rule (TSR) is that with warming, body size of the weevil species on both MI and PEI should decline. However, predation by mice of the weevils on MI should fundamentally affect the pattern of such change, causing it to differ from neighbouring PEI, indicating synergistic impacts between climate change and invasions. Analysis of a 24-year data set indicates a decline in the body size of all weevil species on PEI with increasing temperature. However, on MI, a negative relationship between mean annual temperature and body size is found only for Palirhoeus eatoni, a species not eaten by mice. A possible explanation for the positive relationships found for the other species could be due to higher metabolic demands imposed on mice in colder years than in warmer ones. Any increase in predation coupled with a preference for larger sizes, which the mice clearly show, would lead to a decline in the mean size of the weevil species. Due to the relationship between body size and metabolic rate and the importance of the weevils in the islands' food webs, changes to the body size of these organisms could have significant consequences for the island ecosystems' functioning.
The thermal environment experienced by organisms also has a direct effect on survival, growth and reproduction. The physiological response of organisms to rapidly changing climates is therefore a primary concern. Organisms may respond to variable environmental conditions through phenotypic plasticity as well as behaviour. Chapter 5 of this thesis shows that of the weevil species and populations investigated on MI, most display phenotypic plasticity, the form of which is in keeping with the 'Hotter is Better' hypothesis. This could be due to rare extreme temperature events and the advantage for the performance curves to incorporate high temperatures experienced in the environment. Mismatches between thermal optima and preferred temperatures displayed by all species could mean that these weevils are well equipped to cope with warming conditions on MI unless the prediction of an increase of rare extreme events such as extreme temperatures is realised.
Rapidly changing climates and an increase in the introduction of non-indigenous species are issues of major conservation concern. This has increased the significance of studies on the impacts of these threats. However, this thesis shows that to understand such processes, it is essential that an integration of disciplines be undertaken. This thesis thus adopts a multidisciplinary approach and highlights key issues associated with both climate change and biological invasions. The patterns and predictions of species and community responses to these environmental changes are complex. Moreover, predicting such responses is likely to be problematic, especially as multiple factors will change concurrently and how these factors might change is unclear. This highlights the importance of long-term records for understanding organism responses to such changes. Furthermore, impacts on indigenous species are likely to be exacerbated by the predicted increase in the rate of introductions with climate change. This makes the case for preventing the dispersal of invasive species to new areas all the more important.
To assess the impacts of climate change and invasive species in the sub-Antarctic
https://doi.org/10.5281/zenodo.4751646
oai:zenodo.org:4751646
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751645
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
species-energy relationships
thermal biology
body size
abundance structure
Climate change
invasive species
sub-Antarctic
Marion Island
PhD
Climate change and invasion impacts in the sub-Antarctic
info:eu-repo/semantics/other
oai:zenodo.org:4751606
2021-12-31T00:02:22Z
openaire_data
user-cib
Griffiths, Charles
Marr, Sean
2014-05-05
Freshwater fishes are among the most threatened taxa in the world. Increasing demand for freshwater, habitat degradation and the introduction of non-native species, will continue to place pressure on the remaining native freshwater fishes. A meta-analysis estimated that more than 90% of river habitat in three major catchments has been invaded by non-native fish and that catchments covering less than 1% of Cape Floristic Region have no recorded non-native fish introductions, the major rivers containing 10 or more non-native species. The majority of the native fishes continue to be threatened by the presence of non-native fish.
Profound taxonomic and functional changes to freshwater fish assemblages in Mediterranean-climate regions resulting from non-native fish introductions were identified. Phylogenetic preference was exhibited for species selected with more than 90% of introductions originating from five taxonomic orders. The pathways for introductions were consistent across all Mediterranean-climate regions. The results show strong evidence of on-going taxonomic and functional homogenization of freshwater fish faunas. Characteristics suitable for risk assessment databases in Mediterranean-climate regions were identified.
The difficulties associated with attempting to identify the reasons for the decline of a critically endangered fish, even for a relatively simple system, were demonstrated. Water quality, pesticide exposure, instream and riparian zone habitat, and dietary overlap between native and non-native species were explored. The results of the study were inconclusive. The results do indicate that native and non-native species can co-occur in the complex habitat of one tributary, but not in the simple habitat of the other.
A social survey of freshwater anglers showed that angling for non-native species is important to the anglers and that they are not likely to switch to angling for native species, with the possible exception of Clanwilliam yellowfish. The anglers considered the conservation of native fishes extremely important but less than half believed that the conservation authority were doing a good job in conserving native fishes. The results indicate that support for the conservation authority's proposed piscicide project is low but that it could increase support for conservation projects by using large cyprinids as flagship species. Many options are available to the conservation authority to improve their efforts to manage non-native fishes in the region. The most important of these are the delineation of roles and responsibilities and the compilation of a comprehensive conservation plan.
Submitted in partial fulfilment for the Degree of DOCTORATE OF PHILOSOPHY in the Department of Zoology
https://doi.org/10.5281/zenodo.4751606
oai:zenodo.org:4751606
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751605
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
freshwater fishes
Cape Floristic Region
non-native species management
PhD
Conservation of the native freshwater fishes of the Cape Floristic Region (South Africa): management of non-native species
info:eu-repo/semantics/other
oai:zenodo.org:4761496
2021-12-31T00:02:13Z
openaire_data
user-cib
Chown, Steven
Lee, Jennifer
2011-09-01
This dataset provides information on the abundance, body size variation and sex ratio of an indigenous spider, Myro kerguelenensis, across an altitudinal gradient on sub-Antarctic Marion Island.
Although spiders are a diverse and ecologically important group of predators across the sub-Antarctic islands, relatively little is known about their biology. Therefore this data was collected to provide baseline data for spider abundance and body size on Marion island
https://doi.org/10.5281/zenodo.4761496
oai:zenodo.org:4761496
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761495
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Marion Island
Spider
Altitudinal gradient
Post-doc
Myro Kerguelenensis density and body size on Marion Island
info:eu-repo/semantics/other
oai:zenodo.org:4772719
2021-05-20T13:48:12Z
openaire_data
user-cib
Chown, Steven
du Plessis, Dorette
de Morney, Melanie
2014-09-26
<p>The Iimbovane Outreach Project investigates the abundance and diversity of ants along two extensive transects through the Fynbos and Succulent Karoo biomes of South Africa. It is a long term project initiated in 2005 by Principal Investigator Prof. S.L. Chown, Stellenbosch University. Data collection is carried out by Grade 10 learners and the Iimbovane team on a biannual (spring and autumn) basis.</p>
To investigate changes in invertebrate assemblages, specifically ants, in space and over time in different natural and modified landscapes of the Western Cape.
https://doi.org/10.5281/zenodo.4772719
oai:zenodo.org:4772719
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4772718
info:eu-repo/semantics/restrictedAccess
biodiversity
Fynbos
altitudinal gradient
invertebrate diversity
species richness
ants
Longterm Data
Iimbovane Outreach Project: Ant data
info:eu-repo/semantics/other
oai:zenodo.org:4757155
2021-12-31T00:02:12Z
openaire_data
user-cib
McGeoch, Melodie
Luruli, N
2007-08-14
Invasion by the notorious tramp species, the Argentine ant (Linepithema humile Mayr) (Hymenoptera: Formicidae) has caused major concern around the globe, owing to its displacement of native ant species and other invertebrates where it invades. This species was first recorded in South Africa in 1901 in Stellenbosch, Western Cape Province (WCP), and has now become a significant pest in most urban and agricultural areas in the country. The Argentine ant has received relatively little attention in South Africa compared to other countries (e.g. California, North America). To date the extent of invasion by this species countrywide, as well as its impact on the local ant fauna inside protected areas, has not been quantified. In this study, the impact of the Argentine ant on native ant fauna inside three protected areas in the WCP (Helderberg Nature Reserve (HNR), Jonkershoek Nature Reserve (JNR) and Kogelberg Biosphere Reserve KBR)) was assessed. Species richness and diversity were compared between invaded and uninvaded bait stations at each protected area. Several native ant species were found to be displaced by the Argentine ant from all three protected areas, although three species: Meranoplus peringueyi, Monomorium sp. 8 and Tetramorium quadrispinosum, were found coexisting with it. Invaded bait stations had significantly lower ant species richness and species turnover than uninvaded bait stations. Uninvaded bait stations contained eight times more native ant species than invaded bait stations. Thus, the invasion of protected areas by the Argentine ant has severe negative consequences for the species richness and assemblage structure of native ants, leading to the biotic homogenization of these local ant communities. The distribution range of the Argentine ant inside the three protected areas (HNR, JNR, KBR), as well as microhabitat preferences that may facilitate the spread of this species inside these reserves, was also assessed. Helderberg Nature Reserve was the most invaded protected area, with the highest level of the Argentine ant occupancy, while JNR and KBR had lower occupancy levels. At all the three protected areas, this species was dominant at lower altitudinal areas, and also showed a clear preference for areas with high anthropogenic disturbances, i.e. around buildings and on lawns (picnic areas). In this study, there was no evidence that moisture availability facilitates the distribution and spread of the Argentine ant inside these reserves. Finally, a combination of published literature records, museum records and records collected in the current study was used to quantify the current distributional extent of the Argentine ant throughout urban South Africa. This is the first study quantifying the distribution and extent of invasion by the Argentine ant throughout the country. The Argentine ant was found in six of the nine South African Provinces, and its extent of occurrence includes approximately half of the country's land surface area. Discontinuities in the distribution of the Argentine ant across the country revealed that range expansion of the Argentine ant in South Africa is occurring predominantly via human-mediated jump dispersal, rather than naturally via nest diffusion. This study clearly demonstrated that the Argentine ant is well established across South Africa as well as inside protected areas. The Argentine ant invasion was influenced by the presence of human modified landscapes (i.e. buildings) both at low and high altitude, and this was associated with higher rates of native ant species displacement at these areas. Therefore, limiting the development of recreational areas, such as buildings and picnic sites inside protected areas will result in the lower rate of spread of the Argentine ant. This will in turn lower the extent of displacement of native ant species.
To determine the distribution and impact of the Argentine ant in South Africa.
https://doi.org/10.5281/zenodo.4757155
oai:zenodo.org:4757155
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4757154
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Entomology
Masters
Distribution and impact of the Argentine ant, Linepithema humile (Mayr), in South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4740273
2023-02-16T00:02:00Z
openaire_data
user-cib
Wilson, John
Magona, Nkoliso
2018-02-16
While widespread invasions of Australian acacia species (wattles) have been fairly well documented, very little is known about species that have no substantial commercial value or those that are not well-established invaders yet. South Africa has the highest number of invasive wattle species in the world. These have had negative impacts on the environment and socio-economy. However, the last detailed inventory of the group in South Africa was based on data collated forty years ago. In addition, there are several species with small naturalised populations that might pose a future risk. A recent study quantified different aspects of this "invasion debt" for wattles, both for South Africa and globally and found out that southern Africa has a large invasion debt. In Chapter 2 I aimed to determine how many Australian Acacia species are known to have been introduced to South Africa, which species are still present and what their status is. I visited herbaria, arboreta, botanical gardens and conducted field surveys in order to compile a list of introduced wattles, and used DNA barcoding
to confirm the identity of these species. I found records for 114 wattle species introduced into South Africa, but I found the presence of only 50 species. Seventeen of
these species are invasive (16 are in category E, one in category D2 in the Unified
Framework for Biological Invasions); eight species have naturalised (category C3); and 25 species are present but are not known to produce seed in South Africa (category C1). Four of these occur in the Western Cape (three on the Cape Peninsula, A. piligera, A. retinodes and A. viscidula; 1 near Paarl, A. adunca) and two species, A. cultriformis, A. fimbriata in Grahamstown in the Eastern Cape. In Chapter 3, I focus on the potential to eradicate these six naturalised wattle species from South Africa. I carried out a systematic survey of populations and the surrounding areas. For each plant, I recorded plant canopy, height, stem basal diameter, presence or absence of reproductive structures and GPS coordinates. I then
cut or pulled out the plants. I assessed the risk posed by these species using Australian
weed risk protocol and lastly, I determined the current size of the seedbank for these
species. Risk assessment showed that all of these species have high potential impact,
iii hence, they should be considered as a threat. All of these species except A. retinodes can reach reproductive maturity within a year and three of these species have large seedbanks.
If control efforts can continue to prevent reproduction, eradiation will be a matter of reducing the seed banks across the limited distributions for these species. I conclude that eradicating five of the species is feasible and annual clearing resurveys are recommended in order to prevent production of seeds. Acacia cultriformis was clearly at some point used in the ornamental plant trade and there are many isolated populations. This makes it difficult to find all plants and eradication is unfeasible. I conclude with Chapter 4, where I provided recommendations for listing and management.
The data set was developed to track the movement of Acacia species and their distribution in order to inform policy for their management
https://doi.org/10.5281/zenodo.4740273
oai:zenodo.org:4740273
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740272
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Invasions
status
Australian acacias
biological invasions
eradication
introduction status
invasive species
management plan
tree invasions
Masters
Determining the invasive status of Australian Acacia species in South Africa, and the potential for eradicating species with limited distributions
info:eu-repo/semantics/other
oai:zenodo.org:4748475
2021-12-31T00:02:16Z
openaire_data
user-cib
Esler, Karen
Vosse, Shelley
2008-06-24
Riparian areas are highly complex systems with varying levels of disturbance that are highly susceptible to invasion by alien plants. Once invaded, riparian areas play a major role in the dispersal and spread of invasive alien plants (IAPs) through the river system and, in some cases, to neighbouring landscapes. Riparian areas have therefore been prioritized by many alien clearing initiatives in South Africa. Current practice for the restoration of cleared areas is minimal and relies mainly on the un-aided recovery of native species from residual individuals and soil stored seed banks. Little research, however, has been done on the effectiveness of this approach or the extent to which riparian seed banks contribute towards community restoration. This study is part of a national research initiative (Targets for Ecosystem Repair in Riparian Ecosystems in Fynbos, Grassland and Savanna Biomes) funded by Department of Water Affairs and Forestry, in collaboration with Working for Water, The Centre for Invasion Biology and the Universities of Cape Town, Stellenbosch, Rhodes and Witwatersrand. The initiative undertook to investigate different restoration techniques on various invaded sites for their cost-effectiveness, efficiency, practicality and conservation integrity.
This study has three aims. The first is to determine the composition of seed banks in un-invaded riparian areas within the fynbos biome to be used as a benchmark for future research, restoration grading and other management requirements. The second aim is to determine the composition of seed banks in heavily invaded riparian areas, and thus to assess the impact of invasion on the integrity of the seed banks. The third aim is to evaluate the restoration potential of riparian seed banks following the clearing of invasive alien plants (IAPs).
Study sites were selected within four river systems in the south-western part of the Western Cape Province in South Africa: the Berg, Eerste, Molenaars and Wit Rivers. Plots were selected in both invaded (>75% IAP canopy cover; considered "closed" alien stands) and un-invaded (also termed reference, with <25% IAP canopy cover) sections of the river. Replicate plots were established along varying gradients of elevation (mountain stream and foothill) and moisture regimes (dry, wet and transitional bank zones). Soil samples were collected together with above-ground vegetation surveys and comparisons were made. Results from this study confirm those of previous studies that seed banks offer little reference to current aboveground vegetation, but rather offer insight into past vegetation history as well as future vegetation assemblages.
Worldwide, many of the species that characteristically form seed banks are early successional species. A community study was done for the seed bank based on the species that germinated and were identifiable at termination of the project (6 months after initiation). Three clusters of species could be identified. One group comprised 32 generalist species that occurred in both reference and invaded sections of the rivers. A second group comprised 39 species associated with invaded sites, and a third group of 40 species that was associated with reference sites. A few sub-community groups were found within both the "reference" and "invaded" community groups which were assumed to be habitat specific. Most species were "pioneer" or relatively-short lived, early-successional species which play a vital role in the initial post-disturbance vegetation cover, and facilitate establishment of later successional species.
Seed banks are notoriously variable over space and time, and floristic representation is often biased as a result of differences among species in seed production, dispersal and longevity in the soil. The general consensus is that seeds have an irregular, clustered spatial distribution that is dictated by both biological and environmental factors. Within river systems, the irregular clustering can be exceptionally skewed with the influence of pockets of high sediment deposition along the bank. Environmental factors that were found to significantly skew germination results were the presence of fire, as well as the extent and intensity of invasion (duration and cover). The high level of diversity and abundance in reference Berg River mountain stream seed banks was perceived to be a direct result of a moderate fire frequency (between 8-15 years) and the relatively natural state of the vegetation (i.e. very little invasion). Also, diversity and richness of indigenous species from the Wit and Molenaars Rivers were substantially higher in the invaded samples than the reference samples, probably because both river systems have a long history of invasion and other anthropogenic disturbances which would have an effect on the samples from "reference" sections (i.e. even a 25% presence of IAPs seems adequate enough to alter the composition of the seed bank). Correspondence analyses showed that species had clear affinities towards different levels of "key" riparian environmental variables (fire, invasion and anthropogenic disturbance). Most species were associated with moderate levels of fire frequency, invasion history, and anthropogenic disturbance.
Comparisons of seed bank species assemblages between the lateral and longitudinal variables of the rivers offered insights into the habitat requirements of certain fynbos and riparian species. Most significant were the results from bank zone comparisons which showed distinct species groupings along the different moisture bands. As could be expected, riparian species were best represented within the wet bank zones and fynbos species within the dry bank zone, while species characteristic of both zones occurred in the transitional zone, making this seed bank zone the richest in species. Mountain stream sections were richer and more diverse than foothill sections over both invaded and reference samples. This is hypothesised to be linked to lower levels of anthropogenic disturbance experienced in the mountain stream sections.
The impact of invasion on the riparian seed bank was most clearly shown through the correspondence analyses for the 20 most frequently occurring species. The seed bank assembly patterns were clearly defined by the state of the river (reference or invaded). Interestingly, this pattern was evident at all three spatial scales; landscape (rivers), reach (mountain stream and foothill sections) and habitat (dry, wet and transitional zones). The reference seed bank assemblage was more tightly grouped, implying that the species were more closely associated with each other and less variable than those of the invaded seed bank assemblages. The species groupings within the invaded seed banks were influenced by variables such as reach and zone, whereas the reference seed bank assemblages seem relatively unaffected by these variables. This implies that the presence of invasive alien plants creates additional variation within the seed bank which alters the natural groupings. At a broad scale, the invaded seed banks were less species rich. This means that not only will the resulting seedling community be harder to predict, but it will also have fewer species. However although generally lower in species richness, the seed banks from almost all invaded rivers interestingly showed a higher diversity of indigenous species than their reference counterparts. This is very promising in terms of rehabilitation of post-cleared riparian sites, but more information is needed to understand the seed bank composition and determine how sustainable the seed banks are for rehabilitation in the long-term. All invaded sections had fewer herbaceous perennial species but more herbaceous annual species. Graminoids made up 50% or more of the seed bank regardless of state (reference or invaded), while woody species (shrubs/shrublets) were generally more prevalent in the reference samples. These results imply that following the removal of invasive alien plants, the vegetation to regenerate from the seed bank is likely to comprise of short-lived, herbaceous species that are not necessarily an accurate reflection of the indigenous riparian community. It is however important to note that this study investigated only the species that were able to germinate over the study period (6 month germination period). Many riparian species may not have been represented because they are either late germinators or may not be present in the soil seed bank at all. In order to gain a holistic understanding of riparian community recruitment, it is recommended that seed bank studies such as this one be included in a more broad scale, long term investigation which takes into account various reproductive strategies used by riparian species.
Research of this nature is in its infancy worldwide and there are many challenges involved in measuring diversity and change in these systems. However, within the scope of this study, I suggest that these results shed light on previously unanswered and important questions regarding the ecology of seed banks in the riparian ecosystems of the Western Cape.
See abstract above
https://doi.org/10.5281/zenodo.4748475
oai:zenodo.org:4748475
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748474
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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Botany
Masters
The Restoration Potential of Fynbos Riparian Seed Banks after Alien Clearing
info:eu-repo/semantics/other
oai:zenodo.org:4748467
2021-12-31T00:02:26Z
openaire_data
user-cib
Wossler, Theresa
van der Merwe, Julia Francis
2012-01-23
Gas chromatography(cuticular hydrocarbon) and genetic data of fig wasps (Otitesella, Elisabethiella stuckenbergi, Elisabethiella glumosae and Ceratosolen capensis) collected in South Africa.
The dataset was developed as part of a masters project to investigate the inter- and intra-species variation of the cuticular hydrocarbons of fig wasps.
https://doi.org/10.5281/zenodo.4748467
oai:zenodo.org:4748467
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748466
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
fig wasp
cuticular hydrocarbon profile
Agaonidae
Otitesellinae
Masters
Species-specific hydrocarbon profiles of South African fig wasp communities (Hymenoptera: Chalcidoidea)
info:eu-repo/semantics/other
oai:zenodo.org:4757159
2021-12-31T00:02:09Z
openaire_data
user-cib
Richardson, Dave
Potgieter, Luke
2013-11-20
Understanding the processes that drive the invasion of non-native species is often essential for effective management. This thesis focuses on Casuarina spp. – an economically and ecologically important tree genus with taxa that have been widely disseminated by humans. I explore the effects certain taxa can have on community dynamics in recipient environments, investigate the factors that mediate invasion of Casuarina species, and from this aim to develop recommendations for managing the group.
First, I assessed the global introduction history, invasion ecology and the evolution of management approaches of Casuarina. Ten of the 14 species in the genus have been introduced outside their native ranges to over 150 countries, but only three species are recorded as naturalized or invasive. As with other groups there is a correlation between native range size and invasiveness – the three invasive species also have the largest introduced ranges. Propagule pressure explains much more of the variance in observed invasiveness between Casuarina taxa than any known combination of life-history traits. Large-scale plantings of casuarinas in some climatically suitable areas have not yet resulted in large-scale invasions; there is a substantial global Casuarina invasion debt. Experiences in Florida and the Mascarene Islands highlight that casuarinas have the potential to transform ecosystems with significant control costs. Despite modest progress with managing invasions in some areas, substantial problems remain. As with most other invasive tree taxa, complex conflicts of interest are particularly challenging.
Second, I looked at mechanisms underlying naturalization and assessed invasion risk at a regional scale. Here, I examined Casuarina cunninghamiana invasions in the south-western Cape of South Africa – the part of the country with the largest contiguous area climatically similar to the native range of the species. Propagule pressure is a key driver of naturalization of C. cunninghamiana populations in climatically suitable areas. The species also naturalizes in regions with suboptimal bioclimatic conditions, but then only very near (<10 m) planted trees. Risk models indicate that C. cunninghamiana is likely to spread across a greater region of the Western Cape than it currently occupies. Naturalized populations of C. cunninghamiana are young and expanding. The capacity of the species to resprout and attain reproductive maturity at an early age suggests that this species could become a widespread and damaging invader in South Africa. We conclude with some recommendations for management, and argue that if particular steps are taken (e.g. the immediate removal of all female plants from proximity to dams and water-courses; all future sales and plantings to be restricted to male plants) then it might be possible to safely utilise the species in future.
Third, I examined the invasion dynamics of a single Casuarina species at the landscape scale. I explored how interactions between disturbance and invasion govern successional trajectories, using the remarkable invasion of C. equisetifolia on the volcanic island of Réunion. Invasive populations of C. equisetifolia have increased substantially in extent over 40 years. Lava flows have facilitated the spread of C. equisetifolia and invasion of this species has radically changed successional trajectories, increasing the rate of succession sevenfold. This case mirrors work done on Morella faya and Falcataria moluccana on Hawa'ii, which shows the extent to which invasive species can alter ecosystem function and benefit from natural disturbances generated by volcanic lava flows. The continued spread of C. equisetifolia poses a major threat to the small area of remaining native lowland rainforests on Réunion which cover < 2 % of their original extent.
The studies in this thesis have uncovered patterns, processes and invasion risks for invasive trees that are not well represented in the literature. Some insights derived from well-studied tree genera, such as Acacia and Pinus, seem to apply fairly well to tree invasions in general. However, special ecological features of Casuarina species and the ways they are used by humans call for unique considerations when piecing together changing global distributions and creating effective strategies for management.
Write-up of manuscripts and final compilation of MSc thesis
https://doi.org/10.5281/zenodo.4757159
oai:zenodo.org:4757159
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4757158
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
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tree invasions
casuarina
Masters
Casuarina invasions: a multi-scale assessment of an important tree genus
info:eu-repo/semantics/other
oai:zenodo.org:4618035
2021-12-31T00:02:13Z
openaire_data
user-cib
Tammy Robinson-Smythe
Cheruscha Swarts
2014-02-04
<p>Data collected during Cheruscha Swarts honours project</p>
In fulfillment of an Honours degree
https://doi.org/10.5281/zenodo.4618035
oai:zenodo.org:4618035
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4618034
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Sagartia ornata
West Coast National Park
Honours
Sagartia ornata in the West coast national park
info:eu-repo/semantics/other
oai:zenodo.org:4748434
2021-12-31T00:02:03Z
openaire_data
user-cib
van Wilgen, Brian
Guthrie, Gené
2008-05-08
Arundo donax is an invasive species that mostly impacts on sensitive riparian ecosystems. In California, USA, Arundo worsens flood effects, outcompetes and displaces indigenous plant and animal species, creates fire hazards, and has the potential to alter soil nutrient status. Arundo is also invasive in South Africa, though less is known about its ecology, biology, and impacts. Since California and the Western Cape of South Africa have similar Mediterranean-type climates, we could assume that the impacts of Arundo on ecosystems in California are likely to be similar in the Western Cape, and that control methods used could be extrapolated for use in South Africa.
To determine what impact Arundo has on biodiversity at the community-ecosystem level.
https://doi.org/10.5281/zenodo.4748434
oai:zenodo.org:4748434
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748433
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Botany
Masters
Impacts of the invasive reed Arundo donax on biodiversity at the community-ecosystem level
info:eu-repo/semantics/other
oai:zenodo.org:4772773
2021-05-20T13:48:12Z
openaire_data
user-cib
Foord, Stefan
2010-10-15
<p>The Soutpansberg Transect investigates the abundance and diversity of ants and spiders along an altitudinal gradient in the Western Soutpansberg Mountains, South Africa. It has a north-south orientation over the mountain and is a long term project initiated in 2009. Data collection is carried out in intervals that suit the data logger capacity.</p>
To study the diversity patterns in ants and other invertebrate groups across the spatial transect over a long-term period and the climate the invertebrates.
https://doi.org/10.5281/zenodo.4772773
oai:zenodo.org:4772773
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4772772
info:eu-repo/semantics/restrictedAccess
Biodiversity
altitudinal gradient
invertebrate diversity
species richness
climate change
Longterm Data
Soutpansberg Climate Data
info:eu-repo/semantics/other
oai:zenodo.org:4740301
2021-05-06T13:48:09Z
openaire_data
user-cib
Terblanche, John
Steyn, Vernon Murray
2015-11-30
The ability of insects to perform under challenging environmental conditions is paramount to their survival, population growth and evolutionary fitness. Understanding why some organisms persist in certain habitats but not others is the first step to comprehending present, past and future species distributions, of particular importance under future global climate change. Key traits that may assist a species to continue to perform under poor conditions and may potentially assist in surviving future variable and warming conditions include enhanced dispersal capabilities, a wide performance breadth and plastic responses. Repeated mark-release-recapture (MRR) experiments were conducted to measure the performance (dispersal) and plastic responses of the Mediterranean fruit fly, Ceratitis capitata (a prolific global invader). Dispersive and philopatric individuals were morphometrically assessed (including wing size and shape, body mass, abdomen mass, thorax mass and various ratios thereof) to identify phenotypic traits associated with enhanced dispersal. Thereafter, focussed laboratory experiments were undertaken to determine which aspects of flight performance are enhanced, or associated with, potential dispersal traits. Performance was then compared under various thermal limits (chill coma recovery, CCRT; heat knockdown time, HKDT; critical thermal minimum and maximum, CTmin and CTmax, respectively) to examine the influence of different thermal acclimation regimes and determine the responses of phenotypic plasticity in C. capitata. Subsequently, the costs and benefits of dispersal and its plasticity were measured under semi-field (greenhouse) and field conditions to determine how close laboratory predictions are to the real world. These experiments allowed the discovery of the phenotypic trait associated with dispersal (larger thorax mass: body mass). However, contrary to a widely-held expectation, it did not result in enhanced whole-animal flight performance, but was rather related to willingness to disperse (i.e. dispersal propensity). Furthermore, the
iii
integration of the three operational environments (laboratory, semi-field and field) illustrated that C. capitata's performance is influenced by thermal conditions and highlighted the best acclimation treatment (20°C acclimation, especially in warmer conditions) for enhanced performance. A challenge for invasion biology is the development of a predictive understanding of species invasion ability. Clarity on the species dispersal potential and the factors that influence it is an integral part of the problem. From this study, it is shown that dispersal is condition dependent (e.g. phenotypic traits and behaviour) as well as context dependent (e.g. thermal history and environmental temperature). This may benefit predictions of the future invasion risk of C. capitata and potentially improve current management strategies.
First, to measure the performance (dispersal) of Ceratitis capitata within the native range of this species and determine phenotypic traits associated with dispersive and philopatric individuals. Second, to examine how environmental conditions (in particular, temperature) influence dispersal performance and contribute to short term costs and benefits of phenotypic plasticity in dispersal-related traits.
https://doi.org/10.5281/zenodo.4740301
oai:zenodo.org:4740301
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740300
info:eu-repo/semantics/restrictedAccess
Dispersal
phenotypic plasticity
behaviour
invasion
flight
Masters
Causes and Consequences of Dispersal in the Mediterranean Fruit fly, Ceratitis capitata
info:eu-repo/semantics/other
oai:zenodo.org:4748469
2021-12-31T00:02:27Z
openaire_data
user-cib
McGeoch, Melodie
Vorster, Carlien
2011-11-17
Since its introduction in 1898 into South Africa, the Argentine ant, Linepithema humile, has invaded human-occupied areas (i.e. urban and agricultural areas) and natural areas characterised by few, if any, anthropogenic disturbances. However, compared to other countries in which the Argentine ant has been recorded, and until the past few decades, very little research had been done on this invasive ant in South Africa. Consequently, several issues concerning its ecological and social effects are still under-researched. The first of these issues concerns the lack of knowledge about the distribution of the Argentine ant in the natural areas, particularly the protected areas (PAs), of South Africa. In order to determine how many PAs are occupied by this invasive ant, a study was conducted in the Western Cape Province (WCP). It was found that, of the 614 PAs documented for WCP, ten have a known presence and nine known absence records of the Argentine ant. The remainder of the PAs have no known occupancy records for this ant. A second issue concerns the seasonal bait preference of the Argentine ant in a fynbos habitat. Six bait treatments (two carbohydrate and protein baits, a mixture of the carbohydrate and protein treatments, and a control) were applied in Jonkershoek Nature Reserve (JNR)across a sampling grid in four different Latin Square designs, i.e. once for every season. Based on these experiments, it was determined that the Argentine ant prefers the mixture of carbohydrate and protein treatments, and that this preference does not change according to season. Furthermore, previous studies conducted in JNR (in WCP) determined the existence of a distribution boundary of Argentine ants in an area known as Swartboschkloof. Therefore, the third issue concerned the exact location of the distribution boundary and possible reasons for its establishment. This distribution boundary of the Argentine ant was found to be present 450 m from Swartboschkloof hiking trail. A combination of several explanatory variables may contribute to the maintenance of this boundary, i.e. a change in the horizontal and vertical vegetation distribution, as well as in the slope and aspect across the distribution boundary. With these explanatory variables, the increasing presence of an indigenous ant species, Anoplolepis custodiens, from this boundary may also have contributed to the distribution boundary. The final issue concerns the public perceptions of invasive alien species (IAS) in general and the Argentine ant specifically, at JNR. This study revealed that the majority of visitors to JNR were aware of the presence of IAS in South Africa and in its PAs, while very few visitors knew about the Argentine ant. This study also revealed that future research concerning South Africans perceptions of IAS might play a strong contributing role in conservation.
In fulfilment of a masters degree and the Centre for Invasion Biology
https://doi.org/10.5281/zenodo.4748469
oai:zenodo.org:4748469
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748468
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Argentine ant
distribution
bait preference
public perceptions
Masters
Distribution and bait preference of the Argentine ant in natural vegetation
info:eu-repo/semantics/other
oai:zenodo.org:4761474
2021-05-14T13:48:13Z
openaire_data
user-cib
Clusella-Trullas, Susana
Garcia, Raquel
Morran, Ella E.
2020-01-22
<p>Operative temperature data collected in both "native areas" (native renosterveld vegetation) and "invaded areas" (native renosterveld vegetation areas invaded by alien trees, mainly Acacia saligna). The data were collected using simplified operative temperature models (OTM) of Homopus areolatus tortoises, in four field sites in the Western Cape, South Africa, at an hourly temporal resolution and during one year. For each field site, the data are from between 40 and 45 OTMs placed above- and under-ground and covering a range of microsites that varied in substrate and exposure to the sun.</p>
The aim was to characterise the thermal landscape available to Homopus areolatus individuals in both native and invaded areas, and to explore the effects of invasive trees on the habitat's thermal quality and the individuals' thermoregulation and activity.
https://doi.org/10.5281/zenodo.4761474
oai:zenodo.org:4761474
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761473
info:eu-repo/semantics/restrictedAccess
operative temperature
invasive plants
ectotherm
thermoregulation
Post-doc
Operative temperature dataset in areas with native and invasive vegetation
info:eu-repo/semantics/other
oai:zenodo.org:4633366
2021-12-31T00:02:23Z
openaire_data
user-cib
Natasha Mothapo
Theresa Wossler
Kimberlee Cloete
2013-02-12
<p>Argentine ants have become a major pest in both agricultural and urban areas across the world. The use of toxic baits has been suggested as a possible method of controlling Argentine ant numbers in these areas. One gel and five granular baits containing hydramethylnon, pyriproxyfen or imidacloprid were tested for toxicity and attractiveness during foraging experiments in the laboratory. Gel baits containing imidacloprid were highly attractive to Argentine ants, but do not effectively reduce colony sizes. Granular baits covered in hydramethylnon were the most effective at reducing colony sizes and were relatively attractive to ants. Formulating sucrose gel baits containing hydramethylnon as active ingredient would capitalise on attractiveness and toxicity.</p>
Investigation of the efficacy of commercial toxicants to Argentine ants.
https://doi.org/10.5281/zenodo.4633366
oai:zenodo.org:4633366
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4633365
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Argentine ant
toxic baits
Honours
Argentine ant baiting data
info:eu-repo/semantics/other
oai:zenodo.org:4680416
2021-12-31T00:02:22Z
openaire_data
user-cib
Melodie McGeoch
Nozuko Booi
2007-05-29
<p>This study examines the impact of the invasive Argentine ant on the spatial distribution of the native ant community in fynbos plots in Jonkershoek Nature Reserve, Western Cape Province, South Africa. Both the fine scale distribution and temporal bait colonisation patterns were examined. Two invaded and two uninvaded 50x50 m plots of 50 tuna-baited traps were used to sample the ant fauna (baits left out for between 5 min to 1 h). Results show that where the Argentine ant is present, species richness of native ants is significantly reduced. It also found that with the presence of this invader there are areas which are depleted of ants and two hypotheses are suggested to explain this. It also considers temporal dynamics at bait stations. Native ants shared a bait station with the Argentine ant on only two occasions, and in these cases there were very few Argentine ant individuals present. This study shows that the Argentine ant has a significant effect not only on native ant richness, but also on the distribution and abundance of individual ants at a fine scale.</p>
To plot fine scale distributions of ant species in the presence and absence of the Argentine ant, as well as the fine scale distribuition of the Argentine ant itself
https://doi.org/10.5281/zenodo.4680416
oai:zenodo.org:4680416
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4680415
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Entomology
Honours
Impact of Argentine ant on the native ant community in fynbos: spatial distribution and bait station dynamics
info:eu-repo/semantics/other
oai:zenodo.org:4751611
2021-12-31T00:02:28Z
openaire_data
user-cib
Cowling, Richard
McConnachie, Matthew
2013-07-25
This data set was developed to estimate the factors that best predict the cost-effectiveness of Working for Water treatments in the Kouga and Krom project areas. See thesis and publication for details about the study.
Thesis submitted in fulfillment of the
requirements for the degree of PhD.
https://doi.org/10.5281/zenodo.4751611
oai:zenodo.org:4751611
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751610
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
evaluation
working for water
PhD
On the implementation effectiveness and efficiency of ecological interventions in operational contexts : the case of Working for Water
info:eu-repo/semantics/other
oai:zenodo.org:4740311
2021-05-06T13:48:09Z
openaire_data
user-cib
Esler, Karen
Sibiya, Thabang
2020-03-03
info:eu-repo/date/embargoEnd/2025-03-03
Invasive species are among the biggest drivers of environmental change globally. Because of their ability to alter ecological and evolutionary processes they rank high among the most pressing environmental pressures facing protected areas. However, a major challenge in invasion ecology is identifying priority areas and species, and thus managers are unsure of which to prioritise. Two broad aims were examined in the thesis: 1) to assess if the distribution of alien plants is associated with the habitat template of the Sabie River and 2) to investigate the response of the native plant community to changes in alien plant density and diversity. Vegetation data were recorded in 2004 at 12 sites along the riparian zone of the Sabie River in Kruger National Park. Of these, 11 sites were resampled in February 2015, collated with the 2004 data and assigned trait information. Twenty-one modified Whitaker plots, placed parallel to the river channel and stratified by channel type, were sampled. Native and alien (tree, shrub and herbaceous) species abundance and species richness were recorded in each plot. Plant density, species richness, evenness and composition were examined to assess plant community changes. Alien plant density and species composition differed significantly between channel types, indicating that alien plants are not independent of the channel geomorphology. The dynamic braided channel type had the highest density of alien plants compared to the other channel types. This was not surprising given that most of the alien species in this study were herbaceous and annual species that tend to be ruderal in nature. Furthermore, there were two distinct types of alien plant communities. The first, a disturbance driven community that thrives in alluvial influenced channel types is dominated by ruderal species. The second is a combination of woody and short-lived species that is rooted in the water table within the bedrock influenced channel types. While the herbaceous species thrive in the disturbance driven community, they were not confined to alluvial influenced channel types. As expected, alien plants density was significantly higher than native species, while native species were more species rich. The high density of alien plants correlated with a decrease in native species evenness and species composition. Native and alien species were significantly dissimilar in plant strategies, suggesting that most alien species access or utilise differently to native species. I conclude that the decline in native species with the increase in alien species was an indirect consequence of the competitive dominance of alien species. The decline in native plant density when native and alien species shared a closer combination of plant trait strategies indicates that species with the highest potential to drive change are those that are similar in trait combinations to natives. This result supports the notion that alien species with the greatest potential to compete with natives are those that share a similar combination of traits to natives. By examining the patterns and effects of alien plants along the Sabie River, the study revealed some important considerations for land managers. Land manager could prioritise the bedrock-influenced channel types for alien plant, as they are most likely to be altered by the effects of alien plants. Managers should priorities those alien species that have a similar combination of plant trait strategies to native species, as they have the highest potential to drive competitive exclusion of the less common species.
Eleven sampling locations from a study conducted in 2004 and 2005 by Parsons et al. (2006) were re-sampled during the months of January and February of 2015.
https://doi.org/10.5281/zenodo.4740311
oai:zenodo.org:4740311
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740310
info:eu-repo/semantics/embargoedAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Alien plants
Channel dynamics
Geomorphology
Invasion success
Plant strategies
Riparian habitats
Masters
Riparian plant community change and alien plant invasions following geomorphological change in the Sabie River, Kruger National Park, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4772692
2021-05-20T13:48:12Z
openaire_data
user-cib
Chown, Steven
Khoza, Thembile
2009-11-29
The main aim of the project is to determine the abundance and species diversity of ants and beetles along the altitudinal transect (Cederberg transect). The transect comprises of 17 sampling sites, each with 4 plots from the west coast (Lambert's Bay; sea level) to Wupperthal (Karoo) crossing the Cederberg mountains including Sneeukop Peak (1926 m). The sites are sampled twice a year using pitfall traps.
Was to investigate the change of body size in both males and females specimens per altitude in different years.
https://doi.org/10.5281/zenodo.4772692
oai:zenodo.org:4772692
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4772691
info:eu-repo/semantics/restrictedAccess
Entomology
Longterm Data
Cederberg Beetles Data
info:eu-repo/semantics/other
oai:zenodo.org:4632991
2021-12-31T00:02:19Z
user-cib
Stefan Foord
Colin Schoeman
Vuledzani Oral
2013-08-01
<p>This a an account of reference collection that has been set up for the Department of Zoology as well as the reference collection</p>
Develop a reference collection for the region. Submitted in fulfilment of Hounours project requirement.
https://doi.org/10.5281/zenodo.4632991
oai:zenodo.org:4632991
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4632990
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Collection
Insects
Reference
Honours
Developing an insect collection for the Department of Zoology, University of Venda
info:eu-repo/semantics/other
oai:zenodo.org:4633026
2021-12-31T00:02:31Z
user-cib
Stefan Foord
Audrey Raedani
2013-03-26
<p>Comparative studies have found that, when different sampling methods are used in the same habitat, each of them will contain a few unique species that are not represented in any other sampling method. The efficiency of methods will also vary between habitats. This study made a comparative evaluation of methods used to collect data for estimating ant diversity.in particular, the study aimed to evaluate the efficiency of pitfall traps at estimating ant richness and assemblage structure in varied habitats. The study was conducted in the southern aspect of the Soutpansberg Mountain and it included forest and woodland habitats. A total of 4970 ants (61 species), 6 subfamilies and 27 genera were collected in the four habitats. Overall there was no significant difference between sites (R = 0.057, p = 0.27) accept for a pair-wise comparisons between close woodland and Gallery forest (R= 0.15, P= 0.03). Pitfall species richness predicted 94% of the total site species richness (R2 0.94). Baiting was the worst predictor of species richness (R2 =0.02). Active search predicted (R2 = 0.29) of the total species richness and Winkler extraction predicted (R2 =0.35) of the total species richness.Winkler extraction had the highest inventory completion (93%), followed by Bait (91%), Pitfall traps (89%) then active search with the lowest (85%).Overall there was no significant difference between Habitats (R = 0.057, p = 0.27)accept for a pair-wise comparisons between close woodland and Gallery forest (R= 0.15, P= 0.03 There was a resemblance in species caught in closed woodland and species caught in the gallery forest, points were closer to each other. There was a significant difference between methods (R = 0.374, p = 0.01*) except for the comparison between active searching and Winkler which showed low significance (R= 0.07, P = 0.8). The MDS of methods suggest that pitfall trapping clearly caught a different set of ant assemblages, which was also true for baiting, but to a lesser extent. Although pitfall trapping was not exhaustive in terms of species caught it is a viable surrogate for comparative studies of species richness and assemblage structure for ants in these varied habitats.</p>
Evaluate the effect of different sampling techiniques and habitats on the estimation of ant diversity
https://doi.org/10.5281/zenodo.4633026
oai:zenodo.org:4633026
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4633025
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Pitfall
Winkler extraction
Active search
Baiting
Species density
Abundance
Species richness
Thicket forest
Gallery forest
Open woodland
Closed woodland
Honours
Inventory completion and complementarity of ant assemblages in a variety of habitats and a suite of sampling methods
info:eu-repo/semantics/other
oai:zenodo.org:4621257
2021-12-31T00:02:26Z
user-cib
Stefan Foord
M.P. Tshisikhawe
Sebua Semenya
2013-08-06
<p>The spread of plants from one country to another through intentional and unintentional human activities is a serious threat to the world’s biodiversity; second only to habitat destruction. However, a number of studies have shown that invasive alien plant species can positively contribute to rural economies. This paper is an attempt to document a few of these species ‘positive contribution to rural inhabitants’ well-being in and around Thulamela Local Municipality in Vhembe District of South Africa. Information on the uses of invasive alien plant species were obtained in 2010 through interviews with local inhabitants and traditional healers. Twenty one plant species, from 15 families, were found to be utilized by rural inhabitants. These species are important sources of food and medicine, provide firewood, and are of aesthetic value. They have become alternative sources of utilization, where the indigenous vegetation has been decimated by overexploitation. This study postulates that their extensive use, under careful management, could form part of a strategy for social upliftment and environmental management in poor rural municipalities.</p>
Develop an understanding of the use of alien invasive plant species by people in Venda
https://doi.org/10.5281/zenodo.4621257
oai:zenodo.org:4621257
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4621256
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
utilization
Invasive alien species
InThulamela Local Municipality
Honours
The utilization of some alien invasive plants species around Thulamela local municipality of Limpopo Province, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4751648
2021-12-31T00:02:12Z
user-cib
Griffiths, Charles
Uys, Charmaine
2014-05-05
While the Cape Peninsula (South Africa) is renowned for its exceptional plant and invertebrate
diversity and endemism, extensive alien plant invasion and exotic pine plantations reduce native
species richness, and may facilitate alien invertebrate invasions. This study examines the
impact of planting and felling pine on litter invertebrate communities, by comparing invertebrate
diversity and faunal exchange between pine plantations and two types of native vegetation
(Afrotemperate forest and fynbos). Impacts of the worst invasive alien invertebrate (Argentine
ant, Linepithema humile) and other alien invertebrate species are investigated. This is one of
the first attempts to inventory and quantify impacts of non-ant alien invertebrates in Table
Mountain National Park. The entire ground-dwelling invertebrate community was sampled at 31
sites in summer 2008/2009, using soil cores, leaf litter samples, pitfall traps, sugar-baited ant
traps, and decayed logs. A total of 112 404 individuals representing 728 species (10 classes
and 38 orders), including nine Cape Peninsula endemic and 19 alien invertebrate species, was
collected. Pine plantations supported lower species richness and abundance, and different
community assemblages, compared to Afrotemperate forest, but similar species richness to
fynbos. Pine plantations shared fewer species with fynbos than forest, thus negatively affected
fynbos-specialist invertebrates, because afforestation reduces available fynbos habitat. Alien
species richness was similar across habitats. Argentine ants, like most other alien species
identified, were present in all habitats, but were the most abundant ant species at only four
forest, two fynbos and two pine plantation sites. The impact of Argentine ant invasion on native
ant communities was evaluated using species richness and community composition analyses,
the functional group approach, and species co-occurrence patterns, and provided evidence for
displacement, impoverishment, and community disassembly. No clear impacts of the 18 non-ant
alien species on the abundance, species richness, or community composition of corresponding
native taxa were detected. However, carnivorous molluscs and European wasps (Vespula
germanica) require careful monitoring. Using a reiterative process, ant species and functional
groups were selected as the best ecological indicators of restoration progress in fynbos
following clear-felling of pine. These findings have application to other Mediterranean-type
ecosystems impacted by exotic pine.
Submitted for the Degree of DOCTOR OF PHILOSOPHY in the Department of Zoology
https://doi.org/10.5281/zenodo.4751648
oai:zenodo.org:4751648
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751647
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
invasive woody plants
PhD
Invasive woody plants: a double-edged sword for invertebrate conservation
info:eu-repo/semantics/other
oai:zenodo.org:4761502
2021-12-31T00:02:18Z
user-cib
McGeoch, Melodie
Spear, Dian
2012-03-07
Dates of signatory to international policy (conventions and agreements of organisations) relevant to
controlling invasive alien species.
Dates of signatory for RCW and WTO are adjusted to date of relevant resolutions. International
agreements and conventions: Cartagena Protocol on Biosafety (CPB), Convention on International Trade
in Endangered Species of Wild Fauna and Flora (CITES), International Plant Protection Convention (IPPC),
The Ramsar Convention on Wetlands of International Importance especially as Waterfowl Habitat
(RCW), Convention on the Conservation of Migratory Species of wild animals (CMS), World Trade
Organisation agreements (WTO), Protocol on Environmental Protection to the Antarctic Treaty (PEPAT),
United Nations Convention on the Law of the Sea (UNCLOS), Convention on International Civil Aviation
(CICA) and International Maritime Organisation agreements (IMO).
These data were used as a global indicator of policy response to the invasive alien species problem.
https://doi.org/10.5281/zenodo.4761502
oai:zenodo.org:4761502
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761501
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Policy
alien species
global
Post-doc
Dates of signatory to international policy (conventions and agreements of organisations) relevant to controlling invasive alien species.
info:eu-repo/semantics/other
oai:zenodo.org:4633328
2021-12-31T00:02:10Z
user-cib
Stefan Foord
Simba Dembe
2013-03-26
<p>Pheidole megacephala (Fabricius, 1793) is an ant species of the family Formicidae that includes at least ten subspecies. It is one of the three species that are found across the Soutpansberg Mountain. The mountain is characterised by a strong environmental gradient and raises the question whether the taxon includes cryptic species. The study was conducted along a north-south altitudinal transect. We hypothesized that P. megacephala found in this transect is one species. DNA barcoding was used to determine if there are any cryptic species within this species group. DNA extraction was conducted on the whole ant using the Qiagen extraction kit after which the DNA was viewed on a 1.75% agarose gel. The polymerase chain reaction was used for DNA amplification, followed by sequencing and phylogenetic analysis where the Neighbour joining, Maximum likelihood and Maximum. Sequence extraction and amplification was only successful for two specimens. Phylogenetic analysis suggests that the two specimens belong to different clades, and that P. megacephala species group along the mountain consist of cryptic species. These conclusions are however confounded by the small sample size and the possibility of misidentifications based on morphology</p>
Baseline ants data for altitudinal transect and factors that genetically determine if the P. megacephala species group found in the Soutpansberg consist of one or several species.
https://doi.org/10.5281/zenodo.4633328
oai:zenodo.org:4633328
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4633327
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Cryptic species
DNA barcoding
Phylogenetics
Lajuma
Honours
Should we lump or split? The case of the Pheidole megacephala species group along a strong environmental gradient in the Soutpansberg Mountains in the Limpopo Province, South Africa?
info:eu-repo/semantics/other
oai:zenodo.org:4757178
2021-12-31T00:02:19Z
openaire_data
user-cib
van Rensburg, Berndt
Wolmarans, René
2010-10-04
Ecological niche modeling is a method designed to describe and predict the geographic distribution of an organism. This procedure aims to quantify the species-environment relationship by describing the association between the organism's occurrence records and the environmental characteristics at these points. More simply, these models attempt to capture the ecological niche that a particular organism occupies. A popular application of ecological niche models is to predict the potential distribution of invasive alien species in their introduced range. From a biodiversity conservation perspective, a pro-active approach to the management of invasions would be to predict the potential distribution of the species so that areas susceptible to invasion can be identified. The performance of ecological niche models and the accuracy of the potential range predictions depend on the quality of the data that is used to calibrate and evaluate the models. Three different types of input data can be used to calibrate models when producing potential distribution predictions in the introduced range of an invasive alien species. Models can be calibrated with native range occurrence records, introduced range occurrence records or a combination of records from both ranges. However, native range occurrence records might suffer from geographical bias as a result of biased sampling or incomplete sampling. When occurrence records are geographically biased, the underlying environmental gradients in which a species can persist are unlikely to be fully sampled, which could result in an underestimation of the potential distribution of the species in the introduced range. I investigated the impact of geographical bias in native range occurrence records on the performance of ecological niche models for 19 invasive plant species by simulating two geographical bias scenarios (six different treatments) in the native range occurrence records of the species. The geographical bias simulated in this study was sufficient to result in significant environmental bias across treatments, but despite this I did not find a significant effect on model performance. However, this finding was perhaps influenced by the quality of the testing dataset and therefore one should be wary of the possible effects of geographical bias when calibrating models with native range occurrence records or combinations there of. Secondly, models can be calibrated with records obtained from the introduced range of a species. However, when calibrating models with records from the introduced range, uncertainties in terms of the equilibrium status and introduction history could influence data quality and thus model performance. A species that has recently been introduced to a new region is unlikely to be in equilibrium with the environment as insufficient time will have elapsed to allow it to disperse to suitable areas, therefore the occurrence records available would be unlikely to capture its full environmental niche and therefore underestimate the species' potential distribution. I compared model performance for seven invasive alien plant species with different simulated introduction histories when calibrated with native range records, introduced range records or a combination of records from both ranges. A single introduction, multiple introduction and well established scenario was simulated from the introduced range records available for a species. Model performance was not significantly different when compared between models that were calibrated with datasets representing these three types of input data under a simulated single introduction or multiple introduction scenario, indicating that these datasets probably described enough of the species environmental niche to be able to make accurate predictions. However, model performance was significantly different for models calibrated with introduced range records and a combination of records from both ranges under the well established scenario. Further research is recommended to fully understand the effects of introduction history on the niche of the species.
To investigate the impact of geographical bias in native range occurrence records on the performance of ecological niche models for invasive alien plant species and to compare the performance of ecological niche models when calibrated with (1) native range records (2) introduced range records and (3) a combination of both, for invasive alien plant species with different simulated introduction histories.
https://doi.org/10.5281/zenodo.4757178
oai:zenodo.org:4757178
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4757177
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Ecological niche modeling
Alien invasive plant species
Masters
Investigating the influence of data quality on ecological niche models for alien plant invaders
info:eu-repo/semantics/other
oai:zenodo.org:4680440
2021-12-31T00:02:27Z
openaire_data
user-cib
Mark Robertson
Rene Wolmarans
2007-05-11
<p>In South Africa, the grassland biome is being invaded by a South American herb, commonly known as pompom weed (Campuloclinium macrocephalum). Changes in the natural grassland vegetation are likely to affect the native invertebrate assemblages, but to date it remains unknown how pompom weed affects invertebrate diversity. To quantify this effect, we compared Coleoptera (beetle) and Cicadellidae (leafhopper) assemblages between uninvaded and invaded treatments, as well as the beetle assemblage seperately, divided into canopy-dwelling and ground-dwelling beetles, using unbaited pitfall traps and sweepnet sampling. Specimens were identified to species level and it was shown that the beetle assemblage had a higher species richness in uninvaded sites, but an elevated abundance of certain species in the invaded sites. In contrast, the leafhopper assemblage had a higher species richness in the invaded sites and a four times higher abundance in the uninvaded sites. Ground-dwelling beetles did not show any difference in species richness or abundance between treatments, but canopy-dwelling beetles once again had a higher richness in uninvaded sites and an inflated abundance in the invaded sites. Ordinations showed that invertebrate assemblage compositions asssociated with each treatment were different for all the assemblages studied except the ground-dwelling beetles. Although pompom weed appears to be an attractive resource habitat for certain native invertebrates, some species might be lost if grassland habitats continue to be invaded by pompom weed.</p>
Examine the effects of pompom weed invasion on invertebrate assemblages (beetle and leafhopper) by comparing uninvaded grassland and invaded grassland sites.
https://doi.org/10.5281/zenodo.4680440
oai:zenodo.org:4680440
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4680439
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Entomology
Honours
Investigating the impact of pompom weed (Campuloclinium macrocephalum) on invertebrate diversity in the grasslands of Gauteng.
info:eu-repo/semantics/other
oai:zenodo.org:4680608
2021-12-31T00:02:30Z
openaire_data
user-cib
Berndt Janse van Rensburg
Bradley Reynolds
2007-05-11
<p>A general paucity of studies on the dynamics of invertebrate assemblages exists despite the pivotal role that they play in ecosystem functioning. Altitude and season play vital roles in determining the composition of invertebrate assembalges world-wide. Invertebrate abundance and species richness generally decrease with an increase in altitude and are normally highest in the wet season. Additionally, assemblage composition tends to change dramatically along an altitudinal gradient and between wet and dry seasons. This study investigated the changes that might occur in the composition of Coleoptera assemblages at a low and a high altitude site and between wet and dry seasons in the Sani Pass area of the Maloti-Drakensberg region bordering South Africa and Lesotho, where extremely steep altitudinal gradients and clearly defined seasons exist. Beetle assemblages differed dramatically in composition between altitudinal sites and between wet and dry seasons with relatively little overlap occurring. Studies on the dynamics and composition of beetle assemblages need to include altitudinal and seasonal variations in order to capture the entirety of the assemblages in question.</p>
To determine the effects of season and altitude on Coleoptera assemblage composition.
https://doi.org/10.5281/zenodo.4680608
oai:zenodo.org:4680608
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4680607
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Entomology
Honours
Environmental Effects on Coleoptera Diversity in the Maloti-Drakensberg Region
info:eu-repo/semantics/other
oai:zenodo.org:4748440
2021-12-31T00:02:19Z
openaire_data
user-cib
Wilson, John
Kaplan, Haylee
2012-02-15
This thesis investigates the invasiveness and current status of two Acacia species recently identified as invaders in South Africa in order to determine the feasibility of their eradication. Australian acacias are among South Africa's worst invasive species and many have had widespread damaging impacts on native ecosystems. In addition to widespread species, several acacias still exist as small isolated populations in the country and have been targeted for eradication in order to prevent potential widespread impacts. This work assesses Acacia implexa (Chapter 2) and Acacia stricta (Chapter 3) as potential eradication targets by quantifying the extent of their invasion in South Africa, assessing the risk they pose to the country and evaluating the feasibility of their eradication based on estimated costs of clearing. Results of formal risk assessments show that both A. implexa and A. stricta should be considered high risk species, and bioclimatic model predictions indicate that both species have large potential ranges in South Africa. Detailed population surveys found that A. implexa and A. stricta each occur at several distinct localities all in the Western Cape Province. Acacia implexa populations were found at three sites (Tokai, Wolseley and Stellenbosch) where they have densified by means of vegetative suckering allowing A. implexa to outcompete native vegetation. No evidence of large seed banks of A. implexa were found, however vigorous resprouting following damage makes the control of A. implexa difficult. Acacia stricta was found at nine localities all in the Knysna area of the Garden Route, where populations are spreading along disturbed roadsides in plantations. Acacia stricta produces large amounts of seeds and can accumulate large seed banks. Seed spread is most likely due to large-scale soil movement by road maintenance vehicles which can easily lead to the establishment of new populations. We therefore used a predictive risk mapping approach based on the association of A. stricta to roadsides and disturbed plantations to enable effective searching to detect all infestations of A. stricta. Based on the high risk of both species and the limited range sizes of the currently known populations, we recommend that A. implexa and A. stricta remain targets for eradication. Management strategies proposed for these species (Chapter 4) include clearing on an annual (in the case of A. stricta) or biannual (for A. implexa) basis to prevent seed production, and targeted awareness campaigns at a national scale to determine whether our current knowledge of the extents of A. implexa and A. stricta are accurate. This work has shown that detailed assessments of species at intermediate stages of invasion is an important initial step in an eradication attempt, and better understanding of species specific invasion characteristics can help to improve management and potentially increase the probability of success of eradication.
https://doi.org/10.5281/zenodo.4748440
oai:zenodo.org:4748440
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748439
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
early detection
eradication
invasive species
Masters
Assessing the invasiveness of Acacia stricta and Acacia implexa: is eradication an option?
info:eu-repo/semantics/other
oai:zenodo.org:4748462
2021-12-31T00:02:17Z
openaire_data
user-cib
Esler, Karen
Treurnicht, Martina
2011-01-26
This data reports on various aspects related to wildflower farming on the Agulhas Plain. Firstly, by administering a questionnaire, the extent and application of farming practices was investigated. Additionally, the opinion of wildflower farmers (referred to as landholders) about the impact of farming practices on wildflower populations was explored. Secondly, a vegetation survey aimed to assess the impact of farming practices on various structural (regeneration mode and growth form) and compositional attributes (plant family, dominant and rare species) of fynbos.
The Wildflower industry entails various sectors, i.e. social, research, conservation and commerce. No research has focused on the social component of the industry. From an ecological perspective, the implementation of farming practices manifest as anthropogenically induced disturbance events and are a concern for conservation. Previous investigations suggest that farming practices could establish monocultures of commercial wildflower species by reducing species richness and plant diversity of wildflower vegetation. Although the impact of natural disturbance regimes (e.g. fire) and flower harvesting activities have been researched, the impact of farming practices on fynbos structure and composition remains largely unknown. Finally, the Flower Valley Conservation Trust (in joint partnership with CIB) initiated questions addressed in this data/project.
https://doi.org/10.5281/zenodo.4748462
oai:zenodo.org:4748462
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748461
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
fynbos
disturbance
Masters
Wildflower farming on the Agulhas Plain
info:eu-repo/semantics/other
oai:zenodo.org:4745606
2021-12-31T00:02:02Z
openaire_data
user-cib
Clusella-Trullas, Susana
Basson, Christene Helene
2014-01-27
The content of these datasets were used to produce my MSc thesis, regarding the thermal adaptation and responses of physiological and behavioural traits in the lizard Cordylus oelofseni (an endemic lizard with a highly restricted distribution range). The datasets comprise of: resting metabolic and water loss rates of the lizards following exposure to ecologically relevant acclimation treatments and tested at 3 test temperatures, the preferred body temperature of these lizard, microsite operative temperature for 3 months of summer and winter as well as a summary of insects collected at the study site. The second chapter of my thesis looked at the energetic cost of thermoregulation. There are datasets that include distance and time travelled in 4 different "habitat types", time spent basking and energetic data for 7 lizards in each enclosure type. There is also a collection of operative temperatures for each enclosure type used to map the thermal environment in each enclosure type.
To produce a thesis in fulfilment of the degree of Masters of Science, Zoology, at Stellenbosch University
https://doi.org/10.5281/zenodo.4745606
oai:zenodo.org:4745606
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745605
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Lizard
Physiology
Behaviour
Acclimation
Energetics
Thermoregulation
Insects
Adaptation
Masters
Thermal adaptation in the lizard Cordylus oelofseni
info:eu-repo/semantics/other
oai:zenodo.org:4740281
2023-03-01T00:02:01Z
openaire_data
user-cib
Richardson, Dave
McLean, Phil
2018-03-01
List of identified alien plant species in the small town of Riebeek Kasteel, Western Cape, South Africa, from waypoints taken every 10m on each side of all public roads in the town.
To determine whether any patterns existed in the occurrence and abundance of alien and invasive plants within this small town.
https://doi.org/10.5281/zenodo.4740281
oai:zenodo.org:4740281
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740280
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Alien plants
small town
Masters
Patterns and processes of alien plant invasions in small urban areas in South Africa: The Berg River Catchment as a case study (RIEBEEK KASTEEL)
info:eu-repo/semantics/other
oai:zenodo.org:4748438
2021-12-31T00:02:28Z
openaire_data
user-cib
Griffiths, Charles
Haupt, Tanya
2010-12-02
In South Africa, both wild and cultivated oysters are consumed. Edible wild oysters include Striostrea margaritacea, Saccostrea cucullata, Ostrea atherstonei and O. algoensis and all occur along the South and East coasts. These oysters were, or are, exploited commercially, recreationally and via subsistence fishers with S. margaritacea being the most targeted species. The commercial harvesting areas are along the Southern Cape coast and in KwaZulu-Natal. The Southern Cape coast is the largest harvesting area with 102 of the 145 pickers employed in the region. Commercial and recreational harvesting is managed by the Marine and Coastal Management Branch of the Department of Environmental Affairs and Tourism. Data on the total annual catch of oysters in these provinces are minimum estimates, as collectors do not always comply with the harvesting regulations. Subsistence harvesting is largely unmanaged, except in KZN, and is particularly rife in the Eastern Cape Province. The culture of oysters is dependent on importing Crassostrea gigas spat mostly from Chile. Oyster production statistics are only available since 1985, but approximately two million Crassostrea gigas oysters were produced annually throughout the seventies and early eighties. Since then, production has fluctuated over the years with an approximate increase of six million between 1985 and 1991, a decrease of five million between 1991 and 1998, and is presently stable. The establishment and closure of a highly productive farm in the late eighties and early nineties respectively, as well as improved production in recent years, has resulted in these trends. Although the market for oysters has grown, production has not kept up with demand, due to a lack of suitable locations for mariculture purposes. Finding suitable sites for oyster cultivation along the Northern Cape coast and establishing local oyster hatcheries for C. gigas oysters is suggested as the way forward. The latter would also prevent associated marine alien species from being imported with spat. Globally, oysters are well known vectors of marine alien species and despite oyster imports as early as 1894 into South Africa, this topic has been afforded little or no local attention. A visit to various oyster farms in South Africa resulted in the discovery of four newly-recorded alien species: the black sea urchin Tetrapygus niger, from Chile, the European flat oyster Ostrea edulis, thought to be locally extinct following its intentional introduction into South Africa in 1946, Montagu's crab Xantho incisus, from Europe, and the brachiopod Discinisca tenuis, from neighbouring Namibia.
https://doi.org/10.5281/zenodo.4748438
oai:zenodo.org:4748438
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748437
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
oyster
vectors
Masters
History and status of oyster exploitation and culture in South Africa, and the role of oysters as vectors for marine alien species
info:eu-repo/semantics/other
oai:zenodo.org:4745616
2021-12-31T00:02:18Z
user-cib
Hui, Cang
Janse van Rensburg, Marinel
2014-02-10
Much emphasis has been placed on modelling species distributions and less so on the distributional
dynamics. It is important to not only ask where species occur, but why and how they reached a specific
location. Biological invasions provide an ideal natural experiment for studying the drivers and dynamics of
spreading. Here, I examine the drivers and dynamics of the spread of the European Starling, Sturnus
vulgaris, in Southern Africa. Since its introduction in Cape Town in 1897, this top invasive avian species
has rapidly spread across a large extent of South Africa and is continuously expanding its current range. It
is, thus, of great theoretical and management value to elucidate the invasion process and identify key
environmental drivers of its range dynamics.
The aim of this research is twofold. First, I aim to develop realistic suitable habitat maps for the European
Starling in Southern Africa based on multiple climatic and geographic variables using two robust methods
of species distribution modelling (SDM), namely maximum entropy (MaxEnt) and boosted regression trees
(BRT). Second, I aim to, subsequently, develop a hybrid model that runs a dynamic individual-based
model (IBM) on these suitability maps predicted from the SDM. This hybrid model provides an excellent
opportunity to incorporate a variety of response regimes on how behavioural strategies and dispersal
scenarios respond to environmental and geographic features, and as a result leads to a well-rounded study
of the species" distribution dynamics in the region. Independent atlas data and field collections were used
to parameterize and later validate the model. This allowed me to further identify an optimal model through
a parameter sensitivity analysis sorting of the contribution of each environmental and behavioural features
to shaping the past and current geographical range of European Starling.
According to the optimal model, starlings can choose among five sites to locate the one with the highest
habitat suitability. They tend to avoid moving through areas with a 300 m elevation barrier, and the
dispersal distance per year is limited to below 200 km. At the regional scale, the starlings were able to
manoeuvre around mountainous regions and avoided the semi-desert regions of the Karoo. Their
distribution was mainly driven by high winter precipitation along the low-lying coastal regions. Future
projections of their distribution suggested a continuous range expansion throughout the provinces of the
Free State, Gauteng, North West (reaching Mahikeng, the capital of North West, in 2022) and Limpopo
(reaching Polokwane, the capital of Limpopo, in 2046) as well as into the neighbouring countries of
Mozambique and Zimbabwe (reaching Bulawayo, 2nd largest city in Zimbabwe, in 2062).
https://doi.org/10.5281/zenodo.4745616
oai:zenodo.org:4745616
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745615
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
European Starling
niche modelling
individual based modeling
Masters
Reconstructing the range expansion of the European Starling in Southern Africa using a hybrid method of niche modelling and individual based modelling
info:eu-repo/semantics/other
oai:zenodo.org:4751596
2021-12-31T00:02:10Z
openaire_data
user-cib
Chown, Steven
Lee, Jennifer
2009-02-19
Although the impacts of biological invasions are widely appreciated, a bias exists in research effort to post-dispersal processes because of the difficulties of measuring propagule pressure and the detecting of newly established species. Here the Antarctic is used as a model system in which to quantify the initial dispersal of alien species and investigate the factors that contribute to the establishment and range dynamics of alien species once they have arrived in the region.
Human movements are known to transport alien species into the Antarctic, some of which have successfully established and had wide ranging consequences in recipient ecosystems. Considering terrestrial flora, this research found that over 700 seeds from 99 taxa, including some species known to be invasive, are transported into the Antarctic each year in association with South African National Antarctic Programme (SANAP) passenger luggage and cargo. The first ever assessment of propagule drop-off indicated that 30-50% of these propagules will enter the recipient environment. Further results suggested that the construction of the British Antarctic Survey Halley VI station will facilitate the transport of over 5000 seeds from 34 taxa into the region, making this a significant pathway for introductions.
Propagule pressure due to SANAP logistics is also considerable for marine species. Fouling assemblages on the external hull surfaces of the SANAP resupply vessel, the SA Agulhas, form only once the vessel's anti-fouling paint has been damaged by travel through sea ice and are characterised by low diversity. Ice scour prevents fouling assemblages from being transported to the Antarctic continent, but assemblages remain largely intact when travelling to sub-Antarctic Islands. In the sea-chests of the vessel populations of a known invasive, Mytilus galloprovincialis, were found with some individuals having survived transportation to the Antarctic region on multiple occasions.
Once species have overcome initial dispersal barriers, they face further ecological and physiological challenges in order to establish in the recipient region. The parasitoid wasp Aphidius matricariae was first recorded on Marion Island in 2001. Surveys around the island show that adult abundance and the frequency of aphid parasitism are highest adjacent to a common anchor point of the SA Agulhas and decline away from this region. Genetic diversity was low, suggesting that the population was established from a single introduction. This highlights that high propagule pressure is not necessary for successful establishment of introduced invertebrates.
Another species that has overcome the dispersal barrier is the terrestrial slug Deroceras panormitanum, which was introduced to Marion Island in the 1970's and has since spread throughout much of the coastal habitat of the island. For this species range limits are set by intolerance of low temperature and salinity, and abundance structure is characterized by patches and gaps which are associated with this species inability to tolerate dry conditions.
To prevent further alien introductions in the region, targeted management of high risk pathways is required. In addition, increased vigilance is needed to detect and manage newly established aliens before their ranges expand.
To assess propagule movements and establishment of alien species in the Antarctic region.
https://doi.org/10.5281/zenodo.4751596
oai:zenodo.org:4751596
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751595
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Botany
PhD
Alien species and propagules in the Antarctic: movements though space and time
info:eu-repo/semantics/other
oai:zenodo.org:4643938
2021-12-31T00:02:05Z
openaire_data
user-cib
Michael Somers
Mandisa Mgobozi
2011-04-12
<p>Biodiversity is the source of essential goods and ecological services that constitute the source of life for all; despite this there are still some major gaps in our knowledge of biodiversity. One such gap is that of the diversity of spiders in many areas. Knowledge of spider communities is important for a number of reasons i.e. terrestrial arthropod communities are likely to be shaped by spiders as they are at the top of invertebrate trophic levels and can be employed as useful indicators of environmental health. Studies show that spider diversity and density are related to habitat structure. We therefore report on the diversity and density of ground-dwelling spiders in the former Transkei region. Three habitat types were identified and pitfall trapping was employed as a sampling method. A total of 180 individuals from 11 families were collected with family Ctenidae being the most abundant. Alpha, beta & gamma diversities and Simpson’s and Shannon-wiener indices were employed for the different habitats and variation in diversity when comparing different habitats was observed. Results show that habitat selection does affect both diversity and density; with the grassland habitat with highest diversity and riverine habitat with highest density of ground-dwelling spiders.</p>
To report on the diversity and density of spiders in the former Transkei region and relates diversity to habitat structure.
https://doi.org/10.5281/zenodo.4643938
oai:zenodo.org:4643938
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4643937
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
spider diversity
biodiversity
Honours
Diversity and density of ground-dwelling spiders in Dwesa Nature Reserve, Eastern Cape, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4751576
2021-12-31T00:02:06Z
openaire_data
user-cib
Clusella-Trullas, Susana
Allen, Jessica
2016-02-29
Climate change is one of the greatest challenges facing biodiversity today. To understand the responses of ectothermic organisms to increasingly variable climates, it is essential that we understand the patterns of variation in thermal tolerance that occur across spatial and temporal scales. Thermal tolerance measures such as critical thermal limits (CTLs) are at the heart of physiological studies and provide information on the range of temperature at which ectotherms are able to function, and their variation gives key insights into climate change responses. However, within the thermal physiology literature there are several key areas in which controversy has arisen. Notably, in the effects of the rates of temperature change used to assess CTLs, and the effects of acclimation treatments on the same. Furthermore, there is conflicting evidence as to whether low-latitude ectotherm species will be more at risk than high-latitude species from climate change effects, based on the expectations of established macrophysiological rules. The overall aim of this thesis is therefore to investigate these three key areas of controversy in little-studied arthropod groups.
The experimental conditions under which thermal tolerance traits, such as critical thermal limits (CTLs), are assessed can significantly affect the outcomes of such trials. Not only can this lead to erroneous conclusions regarding the thermal tolerance of organisms, but also misinform estimates of vulnerability of which metrics are calculated from thermal tolerance measures. I examined the effects of rate of temperature change on critical thermal limits (CTLs) in two beetle (Tenebrio molitor and Cyrtobagous salviniae), and six Collembola species, using a range of environmentally relevant rates of change; and then examined how the resulting variation in CTLs might feed over into estimates of climate sensitivity based on these measures. Rate of change effects were found to vary between species, latitudinal sites and acclimation treatments. For the Collembola, these effects resulted in significantly different estimates of climate sensitivity between latitudinal groups (subtropical, temperate and polar). The time course of the attainment and reversal of an acclimation response for CTLs was also investigated and found to be significantly different in T. molitor and C. salviniae. These results also suggested that the beetles would have limited capacity to respond to temperature changes over short time scales (hours), such as extreme thermal events; the frequency of which is predicted to increase with future climate scenarios. At a local scale, the thermal tolerance and climate sensitivity of C. salviniae was examined across South Africa to predict whether this species' effectiveness as a biocontrol agent would be affected by predicted increases in temperature in the future. Given the possible benefits of warmer winter temperatures and the possible constraints of higher summer temperatures, the future success of C. salviniae will depend on careful monitoring and strategic reintroductions where necessary. At a broad spatial scale, I examined whether support could be found for several macrophysiological rules that predict thermal tolerance at large spatial scales. Using fifteen Collembola species from latitudinally distinct sites, I found support for Janzen's hypothesis (increasing thermal tolerance breadth with increasing latitude), Gause's rule (negative relationship between basal thermal tolerance and plasticity) and Brett's rule (greater variation in upper compared to lower thermal limits); corroborating a few analyses at global scales using other taxonomic groups. These broad spatial patterns form an important part of understanding ectotherm responses to climate changes at a global scale.
In summary, this study found that the thermal history and experimental conditions under which thermal tolerance estimates are obtained, affect both assumptions of organismal thermal tolerance and estimates of sensitivity to climate warming. These are important considerations when attempting to describe both small and large-scale responses of ectotherms to climate change.
This data is submitted in fulfilment of a PhD degree in the Faculty of Science at Stellenbosch University
https://doi.org/10.5281/zenodo.4751576
oai:zenodo.org:4751576
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751575
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
biological control
macrophysiology
critical thermal limits
rate of change
Curculionidae
Tenebrionidae
Acclimation
Collembola
latitude
lethal temperature limits
thermal tolerance
PhD
Examining the relative contributions of latitudinal variation and phenotypic plasticity to thermal tolerance in arthropods
info:eu-repo/semantics/other
oai:zenodo.org:4740260
2022-11-28T00:02:00Z
openaire_data
user-cib
Measey, John
Ebrahim, Zishan Cassiem
2017-11-28
Species' threat assessments produce generalized threat impact scores, often by considering regional-scale representations of threats. Cities, on the other hand, produce municipal-scale, high resolution data that are proxies for threats; furthermore, cities in mega-diverse regions are home to a high number of threatened species. Prioritization of conservation action is biased for where more information is known (about the ecosystem), and where a positive outcome can be anticipated. Eight Cape peninsula amphibian species have a threatened conservation status. They are isolated on highlands or are restricted to remnant and suburban habitats, dependent on both urban and protected terrestrial and freshwater habitats found in the City of Cape Town and Table Mountain National Park.
In Chapter Two, I used spatial data (shapefiles) to represent threats in a Geographic Information System to spatially define threats to eight amphibian species (five lowland, three upland). I used two approaches: weighted and un-weighted by a threat impact-score, to produce five indices of local threats. The Micro Frog (Microbatrachella capensis) is assessed as the most threatened peninsula frog species by three of the five indices considered. The results show that for lowland species, the threat-class of greatest extent is 'Residential and commercial development'. The three lowland species most exposed to this threat are M. capensis (100% exposed to potential development), Breviceps gibbosus (55.6% of its 8.5 km2 putative peninsula distribution), and Sclerophrys pantherina (38.4% of its 199.7 km2 distribution). The Compounded and the General Threat Index correlate to the (global) Redlist Index (P < 0.05); but no correlation to the regional Red Listing, indicating congruency of threats and threat status.
The Critically Endangered Table Mountain Ghost Frog (Heleophryne rosei) is torrent adapted, and found only on the Table Mountain massif. CapeNature monitors tadpoles, and SANParks monitors (selected) stream parameters. In Chapter Three, I analyse water-habitat monitoring data (controlled for altitude) to show where threats of habitat alteration, drought, or temperature extremes may affect the H. rosei metapopulation. Permanence of water-flow and water temperature are shown to be very highly significant predictors of tadpole presence (p = 0.0005, r = 0.78). The lower the water temperature, the more likely tadpoles are present. Streams with a mean summer temperature greater than 17.2°C (n=3) at 400 to 300 meters above sea level were found to have no tadpoles at this altitude. Permanence of water flow is significant, as tadpoles need more than one year to reach metamorphosis. Summer water temperatures over an average of 17.2°C should be a red-flag for management authorities responsible for bulk-water supply, threat mitigation efforts, and biodiversity conservation.
Spatial indices of threat are useful to illustrate the relative exposure to threats at a local (city) scale. Threats to different lowland amphibians are similar (e.g. residential and commercial development), which varies from the mutual threats to different upland amphibians. Fundamental to stream species' conservation is water supply and demand management, while upland terrestrial species are most affected by veld age and invasive alien flora. Some threats are common for both areas (e.g. invasive alien species).
To produce a matrix or cumulative threats, highlighting hotspots of threat and an index of threats relative to threatened amphibians of the Cape peninsula
https://doi.org/10.5281/zenodo.4740260
oai:zenodo.org:4740260
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740259
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Threat impact score
Threatened areas
GIS
Habitat loss
Amphibians
Table Mountain National Park
Cape Town
Environmental water requirement
Water temperature
Habitat
Masters
AMPHIBIAN CONSERVATION IN AN URBAN PARK: A spatial approach to quantifying threats to Anura on the Cape peninsula
info:eu-repo/semantics/other
oai:zenodo.org:4761478
2021-05-14T13:48:13Z
openaire_data
user-cib
McGeoch, Melodie
Kalwij, Jesse
2008-02-25
Mikros Traffic Monitoring (Pty) Ltd provides a traffic data collection service to various clients. Their biggest client is the South African National Roads Agency for which they operate in the order of 350 Permanent & another 450 Secondary Stations Countrywide on all National Roads. Mikros is also responsible for the traffic counts done for the Western Cape, Eastern Cape, Free State, Northern Cape, North West, Limpopo & Gauteng Provinces. All traffic data collected for these and other clients is kept in an Oracle traffic data database for easy access and distribution. Some of the data collected date back as far as 1994. Based on these traffic density data Mikros issues a 'Traffic Count Yearbook' summarizing traffic on the main National routes of South Africa.
The objective of this summary is to describe the quantity and characteristics of the available data for potential use in CIB research projects.
https://doi.org/10.5281/zenodo.4761478
oai:zenodo.org:4761478
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761477
info:eu-repo/semantics/restrictedAccess
Botany
Post-doc
Summary of South African Traffic Monitoring Data (1994-2006)
info:eu-repo/semantics/other
oai:zenodo.org:4740305
2021-12-31T00:02:12Z
user-cib
Weyl, Olaf
Van der Walt, Kerry Ann
2015-02-10
<p>The Groot Marico catchment in the North West Province is a National Freshwater Ecosystem Priority Area (NFEPA) because it represents unique landscape features with unique biodiversity that are considered to be of special ecological significance. Three native freshwater species Amphilius uranoscopus, Chiloglanis pretoriae and Barbus motebensis, have high local conservation importance and B. motebensis is endemic to the catchment and is IUCN-listed as vulnerable. The main objective of this study is to contribute towards the effective conservation of these three species in the Groot Marico River system by assessing their genetic structure to determine whether tributary populations of the three species comprise of one genetic population or whether they are divided into genetically distinct subpopulations, in order to prioritise areas for conservation. The central null hypothesis was that there is no genetic differentiation between tributary populations (i.e., panmixia) of B. motebensis, A. uranoscopus and C. pretoriae in the Groot Marico catchment, North West Province. In total, 80 individuals per species were collected, targeting at least 10 individuals per population from a total of eight populations (seven tributaries and the Groot Marico main stem) and across the study area. Samples were collected by electrofishing and specimens were euthanized using an overdose of clove oil. A sample of muscle tissue was removed for genetic evaluation and the remainder of the specimens served as voucher specimens. For the genetic evaluation, mitochondrial (ND2, cyt b) and nuclear (S7) genes were used. Genetic techniques used were DNA extraction, polymerase chain reaction (PCR), purification and sequencing. From the 240 individuals collected, 123 sequences for B. motebensis, 111 sequences for A. uranoscopus and 103 sequences for C. pretoriae were analysed across all three genes. Statistical analysis included looking at cleaned sequences in order to obtain models using MODELTEST (version 3.06). Population structuring and phylogeographic analysis was performed in Arlequin (version 2000), TCS (version 1.2.1) and PAUP*. Results indicated that for B. motebensis the null hypothesis could be rejected as there were two distinct lineages (the Draai and Eastern lineages) that demonstrated significant divergence in both the ND2 and S7 genes, suggesting historical isolation. The low divergence in the mitochondrial cytochrome b gene (0% < D < 0.8%) suggests that this isolation is not very old and is probably not comparable to species level differentiation. The null hypothesis was also rejected for A. uranoscopus as there were also significant levels of differentiation between tributary populations resulting in the identification of two lineages (the Ribbok and Western lineages). However, for C. pretoriae, the null hypothesis could not be rejected as there was no genetic differentiation between tributary populations i.e., one panmictic population. Therefore, due to each species showing different genetic structuring within the tributary populations, more than one priority area for conservation needs to be implemented. These priority areas of conservation where therefore evaluated based on the current conservation status of the species (B. motebensis being vulnerable on the IUCN Red List), the number of Evolutionary Significant Units for each species and the overall genetic diversity of all three species in the Groot Marico catchment. In total, four tributary populations were conservation priorities areas, these were the Draai, Vanstraatens, Ribbok and Kaaloog tributaries. The Draai, Vanstraatens and Kaaloog tributaries were selected as priority areas for B. motebensis (B. motebensis is considered to be the most vulnerable of all three species). The Draai tributary was selected due to the B. motebensis population within the tributary showing isolation from the rest of the tributary populations. In order to conserve B. motebensis from the Southern lineage, the Vanstraatens and Kaaloog tributaries were selected. Reasons for selecting these two specific tributaries within the Southern lineage were that the Vanstraatens tributary had unique alleles (three Evolutionary Significant Units) for B. motebensis and the Kaaloog tributary had high genetic diversity (HD = 0.889, ND2 gene) when compared to the other tributary populations. iii The Ribbok and Vanstraatens tributaries were selected as priority areas for the conservation of A. uranoscopus. The Ribbok tributary was selected as it showed isolation from the rest of the tributary populations, as seen with the Draai tributary (B. motebensis) and the Vanstraatens tributary was selected to represent the Western lineage as it had the highest diversity for both genes (ND2 and S7). The Ribbok tributary has the highest prioritisation when compared to the Vanstraatens tributary. Chiloglanis pretoriae occurs within the Draai, Vanstraatens, Ribbok and Kaaloog tributaries, therefore by prioritising these tributaries for conservation, C. pretoriae will in turn be conserved.</p>
Submitted in fulfillment of an MSc degree
https://doi.org/10.5281/zenodo.4740305
oai:zenodo.org:4740305
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740304
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
conservation
fish
genetics
indigenous
Masters
Prioritising native fish populations for conservation using genetics in the Groot Marico catchment, North West Province, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4745651
2021-12-31T00:02:10Z
user-cib
Chown, Steven
Phiri, Ethel
2013-06-13
The main objectives of this research are to examine and test predictions relating
to the relationship between occupancy, abundance, aggregation, and scale on Marion
Island. Additionally, the impact of terrestrial invasive species on indigenous plant
species is investigated, and particularly how they interact with the indigenous plants
and each other.
The thesis is split into five chapters, with the first chapter being a general
introduction to topics of species abundance and distribution patterns as well as alien
species in the sub-Antarctic. In chapter two, the generality of the abundant centre
hypothesis (Brown 1984) is tested by examining the geographic abundance structure
of Azorella selago at an island-wide scale. In the third chapter, the impact of alien
house mice on A. selago as well as the spatial variation in structural damage to A.
selago by mice is investigated at a landscape scale. The fourth chapter focuses on the
distribution and spatial patterns of two alien vascular plant species, Agrostis
stolonifera and Sagina procumbens, and the indigenous Acaena magellanica and how
they interact with each other along rivers. In the fifth and final chapter, the general
findings for each chapter (chapters 2-4) are summarised and synthesised, and the
possible implications and influences of the alien species on macroecological patterns
of Marion Island's indigenous biota are discussed.
In fulfilment of the requirements for the degree of Master of Science
https://doi.org/10.5281/zenodo.4745651
oai:zenodo.org:4745651
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745650
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Azorella selago
Acaena magellanica
Agrostis stolonifera
Sagina procumbens
Mus musculus
Masters
Species occupancy, distribution and abundance: indigenous and alien invasive vascular plants on sub- Antarctic Marion Island
info:eu-repo/semantics/other
oai:zenodo.org:4740285
2021-12-31T00:02:20Z
user-cib
Esler, Karen
Ndhlovu, Thabisisani
2014-04-24
I evaluated the impact of Prosopis invasion and clearing on ecological structure, function and
agricultural productivity in heavily grazed Nama Karoo rangeland on two sheep farms near the
town of Beaufort West in the Western Cape Province of South Africa. My aims were to (1)
determine the effects of invasion and clearing on rangeland vegetation composition, diversity
(alien and indigenous species richness) and structure (alien and indigenous species cover), soil
vegetation cover (plant canopy and basal cover) and agricultural productivity (grazing capacity),
(2) describe the vegetation processes that underlay the invasion and clearing impacts and (3)
evaluate the success of clearing in facilitating unaided restoration of ecological structure,
function and agricultural productivity in formerly invaded rangeland. I hypothesised that
invasion would significantly change rangeland vegetation composition and structure, leading to
greater alien species richness and cover and lower indigenous species richness and cover while
clearing would lead to lower alien species diversity and cover and greater indigenous species
richness and cover. In addition I hypothesized that invasion would reduce rangeland plant
canopy and basal cover and grazing capacity while clearing would substantially increase them.
Finally I predicted that vegetation composition, alien and indigenous species cover and richness,
plant canopy and basal cover and grazing capacity would revert to pre-invasion status and levels
within four to six years of clearing.
Submitted in partial fulfilment of the requirements for the degree
Master of Science in Conservation Ecology
https://doi.org/10.5281/zenodo.4740285
oai:zenodo.org:4740285
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740284
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
prosopis
mesquite
ecosystem structure
ecosystem function
agricultural pdoductivity
Nama Karoo
Masters
Impact of Prosopis (mesquite) invasion and clearing on ecosystem structure, function and agricultural productivity in semi-arid Nama Karoo rangeland, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4751644
2021-12-31T00:02:08Z
user-cib
Richardson, Dave
Thompson, Genevieve
2014-05-05
Large-scale human-mediated movements of organisms promote the establishment of species outside their native ranges and a very small proportion of these species become invasive. Invasive species management typically assumes that introduced species are single, static evolutionary units that are genetically analogous to their native counterparts. However, studies have shown that native and introduced populations of a number of introduced plants differ vastly in their genetic composition. These differences may negatively affect the overall success of control and management programmes, particularly for species that are intra-specifically diverse. The influence of intra-specific diversity on the invasion process was tested in two widely exported tree species that are native to Western Australia, Acacia saligna (three subspecies) and Paraserianthes lophantha (two subspecies).
Thesis submitted in partial fulfillment for the degree of Doctor of Philosophy (Science)
https://doi.org/10.5281/zenodo.4751644
oai:zenodo.org:4751644
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751643
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Acacia saligna
Paraserianthes lophantha
invasive legumes
PhD
Molecular ecology of two invasive legumes (Acacia saligna and Paraserianthes lophantha)
info:eu-repo/semantics/other
oai:zenodo.org:4761504
2021-12-31T00:02:30Z
openaire_data
user-cib
McGeoch, Melodie
Spear, Dian
2012-03-07
A database of animals in national parks in South Africa, their potential impacts and possible pathways of introduction. There is severity of impact information for a subset of species considered to be those species with the most impacts.
https://doi.org/10.5281/zenodo.4761504
oai:zenodo.org:4761504
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761503
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Alien animals
national parks
impact
pathways
Post-doc
Animals in parks database
info:eu-repo/semantics/other
oai:zenodo.org:4740303
2022-03-07T00:02:00Z
openaire_data
user-cib
Measey, John
Thorp, Corey
2017-03-07
Predator-prey interactions are dynamic and the ability to predict their impact on prey species has become an important aspect in ecology. One method to predict the impact of a predator species on a prey population is by analysing the predator's functional response. However, predators are not all functionally similar and may differ intraspecifically. Predators are also not limited to prey from other species as they can cannibalise vulnerable individuals within their own population. The African clawed frog (Xenopus laevis) is a predator with a broad diet, known to consume multiple prey species, including its congeners. They are notorious cannibals with populations consisting of different sized conspecifics. They occur in sympatry with several congeners including the endangered X. gilli which are thought to be under threat through competition, hybridisation and predation from X. laevis. In this study, I investigated the role of predator size on the functional response of X. laevis predators using mosquito larvae (Culex pipiens) as a common prey. I also investigated the threat of X. laevis predation on X. gilli using choice and no-choice experiments to evaluate the relative vulnerability of X. laevis and X. gilli larvae to X. laevis predation. For the functional response experiments, predators were classified by size into small (15-30mm snout-vent length), medium (50-60mm) and large (105-120mm) size classes. Predator-prey interactions were filmed in order to compare handling time and attack rate to the functional response model. In the choice and no-choice experiments, both X. laevis and X. gilli larvae species were collectively and separately exposed to treatments with the presence or absence of a predator. Results showed that the functional response of X. laevis predators change with size: small predators were found to have a Type II response, while medium and large predators had a Type III response. Both functional response and behavioural data showed an inversely proportional relationship between predator attack rate and predator size. Small and medium predators had the highest and lowest handling time, respectively. That the functional response was found to change with the size of predator suggests that predators with overlapping cohorts may have a dynamic impact on prey populations. Therefore, predicting a predator's impact from the functional response of a single size-matched predator experiment may be a misrepresentation of the predator's potential impact on a prey population. Results from the choice and no-choice experiments showed that large X. gilli showed a significantly higher vulnerability to X. laevis predation compared to small X. laevis. Large and small X. laevis larvae, and same size X. gilli and X. laevis larvae showed no significant differences in relative vulnerability. Behaviour may be a factor in contributing to large X. gilli larvae's vulnerability to X. leavis predation, and this will likely have negative implications for the population structure of the endangered X. gilli.
To explain the impact of Xenopus laevis of aquatic ecosystems (including its impact on an endangered species)
https://doi.org/10.5281/zenodo.4740303
oai:zenodo.org:4740303
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4740302
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
functional response
predator
Masters
The impact of Xenopus laevis predation on aquatic ecosystems
info:eu-repo/semantics/other
oai:zenodo.org:4675615
2021-12-31T00:02:19Z
openaire_data
user-cib
Susana Clusella-Trullas
Bettine Jansen van Vuuren
Wilna Jansen
2010-05-03
<p>Dung beetles have been identified as important indicators of habitat change in the Maputaland centre of Endemism, an area of southern Mozambique and northern Kwazulu-Natal in South Africa. Maptutaland harbours one of the rarest vegetation types, sand forest, of which only small portions are currently protected in four conservation parks of South. Sand forest habitats are rapidly undergoing transformation due to increasing elephant browsing activities that create a sand forest-mixed woodland matrix. It has been observed that dung beetle assemblages are significantly different in sand forest and mixed woodland habitats, and if elephant activity continues in sand forest patches, it is predicted that dung beetle assemblages will become more homogenous across habitats. Two habitats, namely undisturbed sand forest and mixed woodland, were sampled and I investigated the morphological differences (wing loading and aspect ratio) of wings across habitats using generalists and indicator species. Low wing loading combined with a high aspect ratio enhances lift production and take-off ability with a mechanical power output improving dispersal abilities in mixed woodland indicator species compared to sand forest indicators. Conversely, predictions regarding generalist species were rejected because they had overall similar wing morphology across habitats. Furthermore, if fragmentation of sand forest patches is not managed, dung beetles are expected to become constrained by their wing morphology and a homogeneous arthropod assemblage will occur across habitats. This could jeopardize long-term studies which use dung beetles to monitor the biodiversity and ecosystem functioning in the MC.</p>
Dataset used to obtain results of wing morphology in different habitats between species (inter and intra results)
https://doi.org/10.5281/zenodo.4675615
oai:zenodo.org:4675615
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4675614
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
dung beetle
Honours
Morphological traits and bioindicators: a case study on dung beetles in the Maputaland Centre of Endemism
info:eu-repo/semantics/other
oai:zenodo.org:4751586
2021-12-31T00:02:02Z
openaire_data
user-cib
Samways, Michael
Gaigher, René
2013-02-19
Alien invasive species are among the most important global conservation threats. Their management is one of the key conservation challenges that will have to be addressed in the next few decades. The study of real invasions and their management in natural ecosystems provides an opportunity to gain important information on theoretical and applied aspects of biological invasions.
This project focuses on the broader ecological context of invasive ant management in an ecologically sensitive island habitat. The thesis has three main components: 1) assessing the role of the invasive ant Pheidole megacephala in the ecosystem and evaluating its threat to the system, 2) developing and evaluating a low-impact management program for the ant, and 3) using a community-level approach to assess ecosystem response to ant removal. A variety of survey methods were used to monitor the island ecosystem before, during and after the management program was initiated.
The ant occupied almost 30% of the island's total land area and reached extremely high densities in some areas. Throughout the infested area the ant was associated with exotic hemipteran scale insects through trophobiotic mutualisms that facilitated high ant and hemipteran abundances. The highly destructive scale insect Pulvinaria urbicola was among the hemipterans that benefited from ant attendance. High levels of hemipteran feeding resulted in dieback of functionally important and threatened native Pisonia trees, which represented a significant threat to the forest ecosystem.
A management program was initiated in response to this threat, consisting of baiting with selective hydramethylnon-based bait delivered in bait stations, accompanied by detailed pre-and post-baiting monitoring. The method was highly effective at suppressing the ants, whilst reducing the opportunity for bait uptake by non-target organisms. It was also cost-effective and adaptable to ant density in the field, but was only effective over short distances. The method may be applicable to other sensitive environments with similar challenges.
After ant control, the ant-scale mutualism was decoupled and the Pu. urbicola population collapsed. There were broad and variable responses in different taxa to the removal of these highly abundant exotic species, the most important of which was the recovery in Pisonia trees. Shoot condition and foliage density improved and there was a decrease in sooty mold. Herbivory on Pisonia increased due to recovery of native canopy herbivores, but the overall impact was far less than that of the exotic hemipterans.
Soil surface arthropods, a group that may have been vulnerable to the treatment method, were unaffected by baiting. Instead, they increased significantly after ant removal, confirming the ant's impact on other arthropods. Other ant diversity increased and there was recovery of the Seychelles endemic Pheidole flavens farquharensis in the baited areas after being at very low population levels before baiting. Non-ant arthropod abundance increased post-baiting, including some functionally important species such as the Indian cockroach.
Natural enemies that interacted predictably with the mutualists were influenced by management. Predators of hemipterans increased significantly after ant removal and were instrumental in the scale population collapse, whereas parasitoids of hemipterans that benefited from the mutualism declined. Additionally, groups that were unrelated to the mutualism were indirectly influenced by management. The natural enemy assemblage as a whole showed recovery to pre-invasion conditions after management.
The study shows how widely interconnected and influential the ant was in the ecosystem. It highlights the threat of the species in natural systems as well as the complex responses following invasive ant removal. Yet, it also demonstrates the potential to safely and effectively manage the species, thereby raising the opportunity for ecosystem recovery.
PhD Thesis and Data
https://doi.org/10.5281/zenodo.4751586
oai:zenodo.org:4751586
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4751585
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Invasive species management
Pheidole megacephala
Ant-scale mutualisms
Pulvinaria urbicola
Arthropod community ecology
Island conservation
PhD
The invasive ant Pheidole megacephala on an oceanic island: impact, control and community-level response to management
info:eu-repo/semantics/other
oai:zenodo.org:4745663
2021-12-31T00:02:17Z
openaire_data
user-cib
Esler, Karen
Strydom, Matthys
2012-05-21
Acacia saligna, or Port Jackson, is an Australian Acacia which has spread throughout the Western and Eastern Cape provinces of South Africa where it has become invasive and a prominent feature of the vegetation. In areas where A. saligna establishes it replaces natural vegetation, alters ecosystem processes and interferes with agricultural practices. Consequently large management efforts have been made to eradicate this invasive alien tree. However, its large and persistent soil stored seed bank, even in the presence of management and biological control agents, poses a serious obstacle to its successful removal. Furthermore the seed bank dynamics of A. saligna over its whole distribution and its variation with environmental conditions in time and space is poorly known. Understanding the seed bank dynamics of A. saligna in time and space is essential for reducing invasive success and achieving management objectives. This study has filled this knowledge gap through studying the seed production and seed bank of A. saligna over its invaded range in South Africa, including how environmental factors influence these factors in time and space. The seed rain of A. saligna was assessed at 10 sites across its distribution in South Africa. The seed rain of A. saligna at the sites was determined through the use of seed rain traps. Twenty five traps were placed out at every site during November 2010 (pre-dehiscence) which was collected again during April 2010 (post-dehiscence). The seed bank of A. saligna was estimated through sampling at 25 sites across its distribution range in South Africa. The seed bank was sampled during April 2010 (post-dehiscence), November 2010 (pre-dehiscence) and April 2011 (post-dehiscence) through taking 50 litter and soil samples at every site which gave a total sampling size of 3 750 for both the seed in the soil and litter over its distribution in South Africa. In addition the average tree diameter, tree density, average number of Uromycladium tepperianum induced galls per tree, the summer aridity index, De Martonne aridity index, winter concentration of precipitation, temperature of coldest month and the soil texture for every site was determined. The damage done by the seed feeding weevil was also estimated for the seed rain study sites. Water availability during the hot summer months was assessed as the most important factor governing seed production and seed bank size. Riparian and non-riparian water regimes were shown to be important in understanding the seed bank dynamics of A. saligna over its distribution range in the Cape Floristic Region. In non-riparian A. saligna populations the seed bank dynamics is limited by both water and temperature and in Riparian A. saligna populations only by temperature. Therefore, two environmental gradients influence the seed bank dynamics of Port Jackson in South Africa. In non-riparian A. saligna populations the number of seed produced and the accumulation of seed in the seed bank generally increases along the west coast of South Africa from Clanwilliam towards Cape Town and along the south coast from Cape Town towards Port Elizabeth. Seed banks are larger closer to the coast, when A. saligna populations of similar age are compared. In Riparian A. saligna populations, the number of seed produced generally increases from Port Elizabeth towards Cape Town and from Cape Town towards Clanwilliam, again, with larger seed banks being accumulated closer to the coast, when populations of similar age are compared. This study provides managers with a useful tool for prioritising management efforts.
The dataset was developed to determine the size of the seed rain and seed bank of Acacia saligna across its distribution in South Africa. Furthermore the study aimed to determine the impact of different abiotic and biotic factors on the seed rain and seed bank of Acacia saligna.
https://doi.org/10.5281/zenodo.4745663
oai:zenodo.org:4745663
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4745662
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Acacia saligna
Seed Bank
Seed Rain
Masters
A perspective on the seed bank dynamics of Acacia saligna
info:eu-repo/semantics/other
oai:zenodo.org:4761472
2021-12-31T00:02:05Z
openaire_data
user-cib
Chown, Steven
Braschler, Brigitte
le Roux, P.C.
2011-01-28
<p>Fresh and dry body mass of ants collected along an altitudinal gradient in the Greater Cederberg Biodiversity Corridor (the CIB's Coast-to-Karoo transect).</p>
Quantification of intra- and inter-specific variation in body mass across a wide range of sites. This project was by the Chown research group.
https://doi.org/10.5281/zenodo.4761472
oai:zenodo.org:4761472
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4761471
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
body mass
Cederberg
altitudinal gradient
ants
Formicidae
intraspecific variation
interspecific variation
Post-doc
Fresh and dry ant body mass along the Cederberg "Coast-to-Karoo" transect
info:eu-repo/semantics/other
oai:zenodo.org:5524338
2022-08-31T15:48:06Z
user-cib
Tinyiko C. Shivambu, Ndivhuwo Shivambu and Colleen T. Downs
2020-08-01
<p>Gastropods are amongst the most popular of the Mollusca in the pet trade, with<br>
globalisation being the main contributing factor facilitating their establishment<br>
globally. Although it is known that gastropods are kept as pets in South Africa,<br>
relatively little has been documented on the trade for this group. Physical pet stores<br>
selling gastropod species were surveyed seasonally in South Africa, aiming to<br>
determine 1) the types of species sold, including their trade popularity, trade volume,<br>
and the biogeographic realms they originated from, and 2) seasonal variations in<br>
gastropod species traded. Six gastropod species were recorded in the South African<br>
pet stores with three known invasives (Achatina fulica, A. immaculata, and Pomacea<br>
canaliculata). Of these species, the African giant snail A. fulica and the channeled<br>
golden apple snail P. canaliculata were the species with higher trade popularity<br>
throughout the year. The trade of the other species fluctuated with seasons among<br>
pet stores and provinces. Gastropod species sampled in this study originated from<br>
four biogeographic realms, with two species from the Afrotropical and Neotropical<br>
realms, and one each from the Indomalayan and the Palaearctic. The number of<br>
gastropod individuals observed in this study was relatively large; as a result, they<br>
may pose a potential risk of invasion should they be released or escape captivity.<br>
The pet trade industry at a national level needs to be regularly monitored and the<br>
policies on selling invasive non-native species should be implemented to avoid the<br>
introduction and establishment of potential invaders.</p>
Funding was provided by the DST-NRF Centre of Excellence for Invasion Biology and the Working for Water Programme through their collaborative research project on "Integrated Management of invasive alien species in South Africa".
https://doi.org/10.3391/mbi.2020.11.3.11
oai:zenodo.org:5524338
Zenodo
https://zenodo.org/communities/cib
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
invasive species, management, ornamental trade, policy implementation, Republic of South Africa
Exotic gastropods for sale: an assessment of land and aquatic snails in the South African pet trade
info:eu-repo/semantics/article
oai:zenodo.org:4650033
2021-12-31T00:02:24Z
openaire_data
user-cib
Charles Griffiths
Tanya Haupt
2010-12-02
<p>Theba pisana (White Garden snail), is native to both Southern Europe and Northern Africa, and was introduced to South Africa in 1881. Since then, it has become widely distributed along the coast, including the West Coast National Park (WCNP). This study aimed to determine the feeding ecology (i.e. feeding duration & consumption rate) of T. pisana, and thus the impact on the vegetation. Field observations to determine the feeding duration was conducted by observing snails on their naturally occurring vegetation every two-hours for twenty-four-hours over varying weather conditions. Temperature (C) and humidity (%) were recorded every two hours. Laboratory experiments were performed to determine the consumption rate of five naturally occurring plant species (Euphorbia mauritanica, Chrysanthemoides incana, Willdenowia incurvata, Ruschia macowanii, Lebeckia spinescence) as well as the cultured diet (cabbage leaves). The results showed that T. pisana are inactive in high temperatures (20.4–28 C), slightly active (10%) in low temperatures (4-8C) and high humidity (85-96%), and largely active (87-96%) when a constant humidity (49-72%) or sudden moisture (e.g. rain) (56-73%) is experienced irrespective of temperature. Snails preferred cabbage leaves (0.089g/day) to the naturally occurring plant species. With approximately 4.04 snails per m2 in the park and snails being active approximately 120 days (i.e. no. of rainy days), the annual potential consumption rate would be 13.5 g/snail on a naturally occurring food item (e.g. Chrysanthemoides incana 0.028g/day). With this low density, T. pisana might not pose an immediate threat, but the eradication is still important for the continual success of the WCNP as a conservational area.</p>
https://doi.org/10.5281/zenodo.4650033
oai:zenodo.org:4650033
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4650032
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Theba pisana
West Coast National Park
Honours
Feeding ecology of the alien invasive pulmonate, Theba pisana (White garden snail), in the West Coast National Park, South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4748425
2021-12-31T00:02:22Z
user-cib
Hui, Cang
Gaboriaud, Coline
2012-01-23
Exotic species are non-native plants or animals that are introduced into areas where they do not naturally occur. Exotic species can out-compete natives by reproducing faster, competing for food and habitat more efficiently, and thrive in the absence of natural predators, and therefore widely expand their distribution range. In such cases, exotic species become invasive and can represent a major threat to global biodiversity, human health and lead to economic losses. South Africa has been subjected to many exotic introductions, some of which have established and became invasive such as the common starling (Sturnus vulgaris). Less than 20 individuals, native from the United Kingdom, were introduced to South Africa in the l890s. One century later, it has become invasive and it is found along the South African West and East Coast from Cape Town to Port Elizabeth. The objective of this study is to understand the population structure and dynamics in order to understand birds' dispersal and spread; two very important points for management and pest control. We sampled common starlings across their distribution in South Africa, and analysed them using microsatellite and mitochondrial data. For comparative purposes, we also included material from Namibia and the United Kingdom. In this study, we differentiate the native population (England) from the introduced population (South Africa-Namibia). Within the introduced range, the observed heterozygosity is of 0.613 compared to 0.698 for the native English population. Genetic differentiation (FST>0.032) between native and introduced has been observed, however no structure in sub-population within the South African population was highlighted. Within the South African population, the genetic similarity between individuals decrease with geographic distance, indicating an isolation-by-distance pattern. The mean average squared of parent-offspring distance (σ²) was estimate to varying between 2 and 10 km². Combination of microsatellites, mitochondrial data and GIS analysis permit to identified short and long distance dispersion in starling populations.
MSc Thesis of an affiliated student
https://doi.org/10.5281/zenodo.4748425
oai:zenodo.org:4748425
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748424
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Sturnus vulgaris
genetic variation
Masters
Patterns of genetic variation in the common starling, Sturnus vulgaris, in South Africa
info:eu-repo/semantics/other
oai:zenodo.org:4772755
2021-05-20T13:48:12Z
openaire_data
user-cib
Chown, Steven
du Plessis, Dorette
2014-09-26
The Iimbovane outreach project investigates the abundance and diversity of ants along two extensive transects through the Fynbos and Succulent Karoo biomes of South Africa. It is a long term project initiated in 2005 by Principal Investigator Prof. S.L. Chown, Stellenbosch University. Data collection is carried out learners on a biannual (spring and autumn) basis.
To provide information on the vegetation at the sites where ants were collected.
https://doi.org/10.5281/zenodo.4772755
oai:zenodo.org:4772755
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4772754
info:eu-repo/semantics/restrictedAccess
biodiversity
Fynbos
vegetation
invertebrate diversity
species richness
ants
Longterm Data
Iimbovane Outreach Project: Vegetation data
info:eu-repo/semantics/other
oai:zenodo.org:4617982
2021-12-31T00:02:07Z
user-cib
Cang Hui
Phathutshedzo Netshabumu
2014-02-10
<p>Niche construction basically means that all organisms modify their environments. Our studies focused on how the cooperator and defectors interact through Prisoner’s Dilemma Games. We also focused on how the cooperators responded to the resources through niche constructions. Our system was solved by determining the equilibrium points and their stability by linearization, and the dynamical stable exit when the death rate is higher that the baseline birth rate, and the cooperation exist. Only the population of cooperation can be able to survive in this rough environment through niche construction, since we assume that only cooperator have the influence in the environment. But Defectors population cannot survive. Also the numerical simulations showed that, the assortment is a necessary condition for the evolution of cooperation in the ecological part.</p>
Submitted in fulfillment of Honours degree
https://doi.org/10.5281/zenodo.4617982
oai:zenodo.org:4617982
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4617981
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Prisoner's Dilemma Games
niche constructions
linearization
Honours
Cooperation of niche-constructing organisms through prisoner's dilemma games
info:eu-repo/semantics/other
oai:zenodo.org:4748458
2021-12-31T00:02:22Z
openaire_data
user-cib
Chown, Steven
Rogers, Andrew
2012-02-15
Bird observation data: Site, date of observation, point number at which observation was made, species name (common and latin), distance to bird, Roberts VII species number, feeding guild, nesting type, foraging substrate, weather during observation.
dataset contains bird observations needed to analysize bird density, species richness, biomass and BSFD
https://doi.org/10.5281/zenodo.4748458
oai:zenodo.org:4748458
eng
Zenodo
https://zenodo.org/communities/cib
https://doi.org/10.5281/zenodo.4748457
info:eu-repo/semantics/openAccess
Creative Commons Attribution 4.0 International
https://creativecommons.org/licenses/by/4.0/legalcode
Birds, invasive species, novel ecosystems, Acacia
Masters
AMR Bird observation data (avian assemblages in alien acacia thickets)
info:eu-repo/semantics/other
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