Functional Consequences of Acute Temperature Stress in the Western Fence Lizard, Sceloporus Occidentalis

One of the ongoing goals of evolutionary biology is to understand geographic variation in organism phenotypes along environmental gradients. Phenotypic differences among populations can reflect local adaptation, which results from genetic differentiation among populations, phenotypic plasticity, which results from phenotypic variation in a genotype along an environmental gradient, or, a combination of both local adaptation and phenotypic plasticity. Environmental temperature is one factor which is known to be highly variable across geographic space and has been shown to affect nearly all aspects of organism development and function in ectotherms, such as growth, feeding, respiration, locomotion, and reproduction. As a result, species with wide geographic distributions that encompass different thermal habitats may experience differing pressures from natural selection and may become locally adapted to their environment so that organismal function is locally maximized. Understanding whether individual populations are locally adapted can help us to better understand the thermal limits of individual species and how those species may respond in changing thermal environments. For this chapter of my dissertation I examined geographic variation in body temperature of the western fence lizard, Sceloporus occidentalis, which is distributed throughout the western United States across a wide range of thermal habitats. My goal was to explore whether or not temperature adaptation has occurred in this species. To do this, I measured field body