Climate dependent heating efficiency in the common lizard

Regulation of body temperature is crucial for optimizing physiological performance in ectotherms. However, time allocated to behavioral thermoregulation is also time lost to engage in other activities. In a heterogeneous thermal environment, ectotherm life history strategies and fitness may reflect the effects of local habitat conditions on an individual’s time budget. Although local adaptation of thermoregulation has been well studied and is known to vary between species or populations, the effects of environment on biophysical adjustments remains elusive. In particular, there are limited data showing that rates of heating (i.e. the speed of body temperature gain) vary in response to environmental conditions. In this study, we explored the effect of environmental conditions on heating rates in the common lizard (Zootoca vivipara). We sampled lizards from 10 populations, in the Massif Central Mountain range of France, and measured whether differences in heating rates of individuals correlated with phenotypic characteristics (i.e. body condition and dorsal darkness) or abiotic characteristics (temperature and rainfall). Our results show that heat gain is faster for larger lizards but also for individuals from habitats with higher amount of precipitation. Altogether, they demonstrate that environmentally induced constraints can shape biophysical aspects of thermoregulation.