No abstract

Thermoregulatory behaviour enables ectotherms to maintain preferred body temperatures across a range of environmental conditions, and it may buffer individuals against the effects of climate warming. In lizards, the mechanism underlying variation in thermoregulatory behaviour has long been assumed to be phenotypic plasticity, and while this assumption has been difficult to test using wild populations in their natural habitat, it has critical implications as to how variation in thermoregulation is incorporated in models designed to predict outcomes of climate change on ectotherms. We continuously recorded one component of thermoregulatory behaviour, light‐environment use, by two wild populations of desert short‐horned lizards Phrynosoma hernandesi occurring at low (warm) and high (cool) elevations. We then reciprocally transplanted lizards and recorded their light‐environment use when exposed to a novel climate at the transplant site. Immediately following the reciprocal transplant to a novel climate, lizards from both populations adjusted their light‐environment use and matched the light‐environment use exhibited by local lizards at that site. This study provides direct empirical evidence that lizards can immediately adjust light‐environment use, one component of thermoregulatory behaviour, via phenotypic plasticity to match the local environment. Our results provide hope that lizards may have some capacity to buffer against climate change by adjusting their light‐environment use to compensate for warmer environmental temperatures. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13071/suppinfo is available for this article.

An individual's morphology is shaped by the environmental pressures it experiences, and the resulting morphological response is the culmination of both genetic factors and environmental (non‐genetic) conditions experienced early in its life (i.e. phenotypic plasticity). The role that phenotypic plasticity plays in shaping phenotypes is important, but evidence for its influence is often mixed. We exposed female neonate diamond‐backed watersnakes (Nerodia rhombifer) from populations experiencing different prey‐size regimes to different feeding treatments to test the influence of phenotypic plasticity in shaping trophic morphology. We found that snakes in a large‐prey treatment from a population frequently encountering large prey exhibited a higher growth rate in body size than individuals in a small‐prey treatment from the same population. This pattern was not observed in snakes from a population that regularly encounters small prey. We also found that regardless of treatment, snakes from the small‐prey population were smaller at birth than snakes from the large‐prey population and remained so throughout the study. These results suggest that the ability to plastically respond to environmental pressures may be population‐specific. These results also indicate a genetic predisposition towards larger body sizes in a population where large prey items are more common.