Ecological variability is associated with functional trait diversity in the western fence lizard (Sceloporus occidentalis)

A major goal of evolutionary ecology is to understand the ways in which ecological variability has structured morphological diversity. The aim of this study was to examine intraspecific phenotypic variation in the western fence lizard (Sceloporus occidentalis) for functional traits previously shown to be linked to variation across latitude and climate at a genus-wide level. We found that body size in S. occidentalis was negatively related to minimum temperatures during the coldest month, potentially implicating overwintering survival as a mechanism leading to this relationship. We also demonstrated that scale size in S. occidentalis was negatively associated with aridity, which is consistent with several other studies in squamate reptiles and the known functional role of scale size in moderating evaporative water loss. However, contrary to predictions of the thermal melanism hypothesis, we found no association between lizard colour and temperature during the active season. Overall, our results are largely at odds with interspecific patterns examining the relationship between these traits and environmental conditions. It is unclear to what degree intraspecific trait variation generally agrees with inferences made at the interspecific level. In any case, more studies at the intraspecific level are needed to resolve this question.