Meeting Abstract
Understanding how organisms cope with seasonal variation in temperature may help better predict how they might respond to future climatic change. This is particularly important for thermally sensitive species like reptiles with temperature-dependent sex determination (TSD), including the red-eared slider turtle (Trachemys scripta). Previous work has shown that incubation temperatures and estrogens act synergistically to produce females, with less estrogen needed for feminization as temperatures increase towards the pivotal temperature (Tpiv) where a 1:1 sex ratio is produced. We also know that levels of maternally derived yolk estrogens are higher in late season clutches relative to early season clutches, but how estrogens and temperature interact under naturalistic, fluctuating conditions is unknown. Can the Tpiv be modified by hormonal shifts acting as a mechanism through which species with TSD may respond to climate change? To address this question, T. scripta eggs were collected throughout the nesting season to sample both early and late season clutches. Eggs were incubated at one of three ecologically relevant regimes: 26.5±4, 27.1±4, 27.7±4 ˚C. These incubation regimes were selected based upon temperatures measured at our field site and a local long-term climatic database. In addition to determining sex ratios and levels of maternally derived estrogens, this project will characterize other phenotypic traits, like behavior, that may also be influenced by seasonal thermal or hormonal shifts. This research will enhance our understanding of the concomitant influences of estrogens and temperatures on TSD, and determine if the Tpiv varies seasonally, which may enhance conservation efforts of species with TSD.
