Meeting Abstract
Despite the prevalence of phenotypic variation in natural environments, we lack the understanding to explain why certain patterns arise along environmental gradients. For species with complex life cycles, adaptive responses to the local environment may be necessary throughout ontogeny since different life stages often occupy different microhabitats. Sessile stages of development are particularly sensitive to changing conditions due to limited behavioral capacities and the small range of microclimatic conditions experienced over small spatial extents (e.g., an egg). Therefore, plasticity in maternal behavior and in the physiology of immobile life stages may be key factors underlying phenotypic variation in some widespread species. To investigate how nesting behavior and embryo physiology may underlie phenotypic variation across the range of a widespread North American lizard, Sceloporus undulatus, we examined responses of mobile and immobile life stages to variation in the thermal environment along a latitudinal cline. First, we compared nesting behavior and nest thermal profiles between the southern and northern reaches of the S. undulatus range. We found that northern females nest in open areas at forest edges while southern females nest at shadier sites. Thus, embryos at hotter southern latitudes experience cooler thermal regimes than their northern conspecifics. We then performed a reciprocal transplant experiment rearing embryos from the northern and southern locations in the laboratory under treatments simulating nest temperatures at those sites. Our results will show how variation in nesting behavior and embryo thermal physiology may contribute to patterns of phenotypic variation across the species range.
