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Published September 29, 2016 | Version v1
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Data from: Fine with heat, problems with water: microclimate alters water loss in a thermally adapted insular lizard

Authors/Creators

  • 1. University of Michigan-Ann Arbor
  • 2. University of Edinburgh
  • 3. National and Kapodistrian University of Athens

Description

Global change, including habitat isolation and climate change, has both short- and long-term impacts on wildlife populations. For example, genetic drift and inbreeding result in genetic impoverishment in small, isolated populations, while species undergo range shifts or adaptive phenotypic change in response to shifts in environmental temperatures. In this study, we utilize a model system in which Holocene landscape changes have occurred to examine long-term effects of population isolation. To examine how isolation may constrain responses to climate change, we characterized ecophysiology across land-bridge island populations of Erhard's wall lizard Podarcis erhardii. We hypothesized that 1) small, isolated populations that are likely genetically depauperate would exhibit lower phenotypic variability; and 2) populations would be adapted to local microhabitat conditions. We compared a population at a low elevation site on the large island of Naxos with two small populations on nearby islets to determine the effects of population fragmentation. We further compared the low elevation Naxos population with two high elevation sites characterized by disparate microclimates to examine the effects of microclimate. To assess the thermal biology and ecophysiological limits of the study species we measured operative body temperatures (Te), field body temperatures (Tb), preferred temperatures (Tp), thermal tolerances (CTmax and CTmin), and evaporative water loss (EWL). Our results indicate that small, isolated populations did not exhibit thermal biology or evaporative water loss, while EWL and thermoregulatory effort varied according to microhabitat characteristics. This study integrates fine-scale measurements with environmental data to provide a holistic view of the relationships between ecophysiology, fragmentation, and microclimate. Our methods can be applied to other ectotherms to gain a better understanding of potential impacts of global change on natural populations.

Notes

Belasen et al. CTmax
Sites are coded as follows: 1 - Naxos Low Elevation (NLE); 2 - Naxos South-Facing (NSF); 3 - Naxos North-Facing (NNF); 4 - Ovriokastro, Small Islet 1 (OVR); 5 - Aspronissi, Small Islet 2 (ASP); Max temp is the maximum temperature at which a lizard could right itself during a laboratory righting test; weight is the weight of the lizard in grams; SVL is the snout-vent length of the lizard in centimeters
Belasen et al. CTmin
Sites are coded as follows: 1 - Naxos Low Elevation (NLE); 2 - Naxos South-Facing (NSF); 3 - Naxos North-Facing (NNF); 4 - Ovriokastro, Small Islet 1 (OVR); 5 - Aspronissi, Small Islet 2 (ASP); temp is the minimum temperature at which a lizard could right itself during a laboratory righting test; duration is the duration of the experiment in minutes; weight is the weight of the lizard in grams; SVL is the snout-vent length of the lizard in centimeters
Belasen et al. adult male EWL
Sites are divided into separate tabs in the spreadsheet. Lizards were given a "number" and an "ID" reflecting unique toeclip combinations. Activity was recorded as either hiding, basking, or foraging. Sex is coded as F for female, F(n) for non-gravid female, F(g) for gravid female, and M for male. Site is coded as follows: 1 - Naxos Low Elevation (NLE); 2 - Naxos South-Facing (NSF); 3 - Naxos North-Facing (NNF); 4 - Ovriokastro, Small Islet 1 (OVR); 5 - Aspronissi, Small Islet 2 (ASP). Activity c and sex c are coded versions of these variables. Body temperature is the internal temperature of the lizard taken with a cloacal thermometer. Substrate temp was the temperature of the substrate on which the lizard was found, and Air temp was the temperature of the air ~5 cm above the substrate. Weight of the lizard was recorded in grams and snout-vent length (SVL) and tail length (TL) in centimeters. Tail condition (TC) was recorded as complete (1 or C) or broken (0 or B). Fragment length (FL) was recorded in centimeters for lizards with broken tails.
Belasen et al. thermal preference data
Site is coded as follows: 1 - Naxos Low Elevation (NLE); 2 - Naxos South-Facing (NSF); 3 - Naxos North-Facing (NNF); 4 - Ovriokastro, Small Islet 1 (OVR); 5 - Aspronissi, Small Islet 2 (ASP). Lizards were given an "ID" reflecting unique toeclip combinations. Sex is coded as F for female, F(n) for non-gravid female, F(g) for gravid female, and M for male. Weight of the lizard was recorded in grams and snout-vent length (SVL) and tail length (TL) in centimeters. Tail condition (TC) was recorded as complete (1 or C) or broken (0 or B). Fragment length (FL) was recorded in centimeters for lizards with broken tails. Date is the date of the thermal preference experiment and start and end time of the experiment is recorded. Temperature was recorded at 2 min intervals for one hour. Mean and quartiles were calculated at the end of the trial.
Belasen et al. adult male EWL
Lizards were given a "number" and an "ID" reflecting unique toeclip combinations. Site is coded as follows: 1 - Naxos Low Elevation (NLE); 2 - Naxos South-Facing (NSF); 3 - Naxos North-Facing (NNF); 4 - Ovriokastro, Small Islet 1 (OVR); 5 - Aspronissi, Small Islet 2 (ASP). Snout-vent length (SVL), trunk girth, tail length (TL), and tail girth were recorded in centimeters. Surface area was calculated as the sum of the SA of the trunk (cylinder) and the tail (cone). EWL was calculated as the difference between final lizard mass and initial lizard mass, divided by number of hours the experiment was run. Any lizards that defecated were re-run. Temperature and humidity were recorded at three time points during the experiment.
Belasen et al. offspring EWL
Data on incubation time and clutch size are recorded for gravid females kept in the laboratory. Snout-vent length (SVL), trunk girth, tail length (TL), and tail girth were recorded in centimeters. Surface area was calculated as the sum of the SA of the trunk (cylinder) and the tail (cone). EWL was calculated as the difference between final lizard mass and initial lizard mass, divided by number of hours the experiment was run. Any lizards that defecated were re-run. Temperature and humidity were recorded at three time points during the experiment. EWLs from babies were recorded and averaged within in a clutch for statistical analyses.
Belasen et al. soil moisture data
Belasen et al. Hobo readouts
In this folder there is a separate excel file for each sampling day at each site. In the filenames, site is coded as follows: 1 - Naxos Low Elevation (NLE); 2 - Naxos South-Facing (NSF); 3 - Naxos North-Facing (NNF); 4 - Ovriokastro, Small Islet 1 (OVR); 5 - Aspronissi, Small Islet 2 (ASP). Readings from before the logger was deployed in the field (during the time between turning the logger on and arriving at the field site) were deleted. Temperature was recorded every 5 min at each site. Loggers are divided into tabs, with loggers 1 and 2 always being deployed in the sun, loggers 3 and 4 in mixed sun/shade, and loggers 5 and 6 always deployed in the shade. Each logger had two probes, thus there are two temperatures (recorded in degrees C) per logger per time point.

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Additional details

Related works

Is cited by
10.1111/oik.03712 (DOI)