Meeting Abstract
Temperature-dependent sex determination (TSD) is a form of sex determination in which incubation temperature during the temperature sensitive period (TSP) determines sex. Previous studies have determined the TSP coincides with the approximate middle third of embryonic development between embryonic stages 14 and 20 of Trachemys scripta. The majority of these studies used constant temperature incubation with a shift to a single temperature during the middle third of incubation to determine the period of temperature sensitivity. There is also evidence that the incubation temperature before the shift may influence the length of the TSP. Additionally, a larger magnitude shift near the end of the TSP can result in greater abundance of sex reversal. It is currently unknown whether the TSP under fluctuating incubation temperatures behave in a similar pattern seen in constant temperature studies or whether larger shifts near the end of the TSP could extend the relative period of temperature sensitivity. In this study, we examined the effects of multiple temperature shift magnitudes as well as the effects of fluctuating incubation temperature on the end stages of the TSP in T. scripta. Eggs were placed under three treatment temperatures: 1) Constant 31°C, 2) 26°C ± 3°C, and 3) 31°C ± 3°C. Eggs were dissected frequently to determine the stage of the embryo and eggs were shifted to incubators with temperatures known to produce the opposite sex at stages before, during, and after the known end of TSP. Eggs were then allowed to incubate until stage 26 where they were sexed. The results of this study have implications in both the physiology of TSD as well as conservational implications when trying to model sex ratios by comparing field data to controlled laboratory studies.
