DOI: 10.5061/dryad.1553pc3
title: Data from: Heat tolerance is more variable than cold tolerance across species of Iberian lizards after controlling for intraspecific variation

description: The widespread observation that heat tolerance is less variable than cold
 tolerance (‘cold-tolerance asymmetry’) leads to the prediction that
 species exposed to temperatures near their thermal maxima should have
 reduced evolutionary potential for adapting to climate warming. However,
 the prediction is largely supported by species-level global studies based
 on single estimates of both physiological metrics per taxon. We ask if
 cold-tolerance asymmetry holds for Iberian lizards after accounting for
 intraspecific variation in critical thermal maxima (CTmax) and minima
 (CTmin). To do so, we quantified CTmax and CTmin for 58 populations of 15
 Iberian lizard species (299 individuals). Then, we randomly selected one
 population from each study species (population sample = 15 CTmax and CTmin
 values), tested for variance homoscedasticity across species, and repeated
 the test for thousands of population samples as if we had undertaken the
 same study thousands of times, each time sampling one different population
 per species. The ratio of variances in CTmax to CTmin across species
 varied up to 16-fold depending on the populations chosen. Variance ratios
 show how much CTmax departs from the cross-species mean compared to CTmin,
 with a unitary ratio indicating equal variance of both thermal limits.
 Sampling one population per species was six times more likely to result in
 the observation of greater CTmax variance (‘heat-tolerance asymmetry’)
 than cold-tolerance asymmetry. The null hypothesis of equal variance was
 twice as likely for cases of cold-tolerance asymmetry than for the
 opposite scenario. Range-wide, population-level studies that quantify heat
 and cold tolerance of individual species are urgently needed to ascertain
 the global prevalence of cold-tolerance asymmetry. While broad latitudinal
 clines of cold tolerance have been strongly supported, heat tolerance
 might respond to smaller-scale climatic and habitat factors hence go
 unnoticed in global studies. Studies investigating physiological responses
 to climate change should incorporate the extent to which thermal traits
 are characteristic of individuals, populations and/or species.
description: <b>Content of dataset: </b>Critical Thermal Maxima
 (CT<i><sub>max</sub></i>) and Critical Thermal
 Minima (CT<i><sub>max</sub></i>) and body weights
 of 304 male individuals belonging to 59 populations and 15 species of
 Iberian lizards (Dryad doi: 10.5061/dryad.1553pc3). Body weight,
 CT<i><sub>max</sub></i> and
 CT<i><sub>min</sub></i> available for all
 populations except the Moncayo/Soria/Spain population of <i>Podarcis
 muralis</i> for which
 CT<i><sub>min</sub></i> was not
 measured. <b>Dataset set used in two research
 manuscripts:</b> Intraspecific variation in lizard heat tolerance
 alters estimates of climate impact / Journal of Animal Ecology (doi:
 10.1111/1365-2656.12914) and Heat tolerance is more variable than cold
 tolerance across species of Iberian lizards after controlling for
 intraspecific variation / Functional Ecology (in press).
 <b>Versions of dataset: </b>the first version of the
 dataset contained CT<i><sub>max</sub></i> data
 alone (Journal of Animal Ecology), species names, population codes,
 locality names (with region, country, lat/long), the second version of the
 dataset (Functional Ecology) contains the latter information along with
 CT<i><sub>min</sub></i> and body-weight data while
 the locality names and lat/long have been refined.
description: <b>Author contributions: </b>Monasterio, Beukema and
 Gómes lead field (lizard sampling) and lab (estimation of thermal limits
 and measurement of body weights) work, and Monasterio and Araújo designed
 experiments. Herrando-Pérez conceived the idea of the two research
 manuscripts (Functional Ecology, Journal of Animal Ecology) and submitted
 the data to Dryad. <b>Funding: </b>MBA
 partly funded through CGL2011-26852 project of the Spanish Ministry of
 Economy and Competitiveness. Field and experimental work funded by
 IC&DT 1/SAESCTN/ALENT-07-0224-FEDER-001755 project led by
 MBA. <b>Acknowledgements: </b>We thank the
 Biological Station of “El Ventorrillo” for hosting the field team and for
 providing the thermal experimental facilities essential for this research.
 We also thank Tim Leerschool, Filipe Serrano and Matthijs Hollanders for
 their support in the field. <b>Collection
 permits: </b>Samples, experiments and use of experimental animals
 supported for Portuguese populations by permits 360 to 362/2014/CAPT and
 550 to 552/2014/CAPT (Instituto da Conservação da Natureza e das
 Florestas), and for Spanish populations by permits (autonomous communities
 in parenthesis hereafter) SGYB/EF/FJRH Re-9H/13 & SGYB/AF/DBP
 Re-79y131/14 (Andalucía), 2014-500201724/2014/02343 &
 INAGA/5000201/24/2013/04434 (Aragón), DGMEN/SEN/avp_13_025_aut &
 DGMEN/SEN/avp_14_020_aut (Castilla La Mancha), P/CYL/101/2013 &
 EP/CYL/106/2014 (Castilla y León), CN0023/14/ACA1587(14) (Extremadura),
 2566/RX131316//clave031/2013 & 2241/RX123724//clave018/2014
 (Galicia), and 10/033298.9/13 & 10/013907.9/14 (Madrid).