Data from: What need for speed? Lizards from islands missing predators sprint slower
Authors/Creators
- 1. University of Michigan-Ann Arbor
- 2. University of California, Santa Barbara
- 3. Eastern Michigan University
Description
Here we test the hypothesis that island species that have evolved in predator-poor environments have reduced locomotor abilities. More than 60% of recent recorded extinctions are from islands 1, and island taxa are often susceptible to invasive predators typically because of the loss of ancestral antipredator behaviors. While locomotor abilities are critical for escaping predation, little is known on how the presence of different types of native predators influences these abilities by maintaining selective pressure. To fill this gap, we documented sprint speed in the Aegean wall lizard (Podarcis erhardii) from Aegean islands (Greece) with varying levels of predation pressure. We show that on islands where mammalian predators were present, lizards sprinted fastest. Lizards sprinted at an intermediate speed where predators other than mammals were present, and lizards sprinted slowest on islands where no predators were present. These results indicate that lizards from the lowest-predation islands are most vulnerable and preventing the introduction of invasive predators should be prioritized for these island systems.
Notes
The three main files used in the analyses were the Dataset 1,2, and 3 files. These files were used for sprint speed analysis, stamina analysis, and island averages respectively.
However, there is a lot of additional data from video analysis. Every sprint video is available and is labeled as the island name and the number of the video (eg. Amorgos1.mp4) the can be found in the zip file for each location (i.e. Amorgos.zip). Video files were analyzed using the program SAVRA (see the link in the methods below), values from this program were then saved into an Excel file that was labeled with the island name (eg. Amorgos5.xlsx). These files were then used in Matlab to calculate velocity (code is in files: get_quintic_spline_and_max_va.m and run_for_all_the_lizards.m). Using this code we obtained velocity (sprint speed) values, that were then saved into Microsoft word documents (eg. amorgosvalues.docx). These values were then matched to the appropriate video, lizard, and trial. This information is available in the file (SemegenetAl Sprint Speed Trial Numbers.xlsx) some trials have more that one video listed because the quality of the video was poor or the lizard failed to run the full distance on camera. These values were then input into the Dataset 1 sprint speed file. Some trials were thrown out because values were significantly off. This data was then input into the main files used for analyses. Correlation tables are in the file labeled "SemegenetAl Pearson Correlations." Results and syntax of mixed models are in the files labled "Sprint Mixed Model Outputs Log10 SemegenetAl" and (Stamina Mixed Model Outputs Log10 SemegenetAl". A detailed methodology is included in the Methods section above.
Funding provided by: University of Michigan
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100007270
Award Number: Rackham Graduate Resources Grant
Funding provided by: University of Michigan
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100007270
Award Number: SNRE Thesis Research Grant
Funding provided by: University of Michigan
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100007270
Award Number: Modern Greek Program
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Additional details
Related works
- Is source of
- 10.5061/dryad.mgqnk991f (DOI)