Meeting Abstract
86.2 Thursday, Jan. 7 Can nest-site choice compensate for the effects of climate change on reptiles with temperature-dependent sex determination? REFSNIDER, Jeanine*; JANZEN, Fredric; Iowa State University; Iowa State University refsnij@iastate.edu
Numerous effects of climate change on ecosystems have been demonstrated. Reptiles with temperature-dependent sex determination may be particularly threatened, as increasing temperatures could lead to skewed sex ratios. A potential compensatory mechanism is nest-site choice, with females selecting nest-sites to match incubation conditions to their latitude. I examined nest-site choice in Chrysemys picta to determine the extent to which local adaptation in nesting behavior is genetically and environmentally based. Gravid females from four transplanted and one local population were housed in a common garden in 2009. Nest-site choice was compared among populations to evaluate variation in nesting phenology, shade cover over the nest, and nest depth. Mid-latitude populations nested earlier than northern and southern populations, but this difference was likely due to variation in life-history traits, as the mid-latitude populations nested 2-3 times, while other populations nested only once. The populations did not differ in shade cover over nests, indicating that, when exposed to novel climatic conditions, females from transplanted populations chose nest-sites with similar shade cover to those of local females. Nest depth was strongly correlated with limb length and, after accounting for variation in female size, populations did not differ in nest depth. These results suggest that while maternal selection of shade cover over a nest-site may be relatively plastic, nest depth is a more rigid character. Therefore, selection of shadier nest-sites may be a mechanism by which female turtles could compensate for climatic warming, whereas alteration of nest depth in response to changing temperatures is less likely and may require a shift in overall female size.
