Dissertation Research: The Evolutionary Significance of Environmental Sex Determination

拟议的研究旨在确定 说明温度依赖的适应意义 性别决定（TSD）在爬行动物和评估的影响， 环境条件对爬行动物自然种群的影响， TSD。 培养温度对生长的影响， 两种海龟幼龟的行为（普通的咬 海龟，Chelydra serpentina和多刺软壳龟， Trionyx spiniferus）进行检查。 一个或两个的相关性 这些性状与孵化温度和后代性别的关系 将提供第一个具体的证据， TSD的意义 当前气候的影响 温度对彩龟幼体性别比例的影响 （emys picta）也将被测量。 该项目将 提供急需的基线信息， 当地夏季温度的波动影响着 TSD的自然人群。 此外，为了调查 全球变暖对TSD物种的影响， 遗传变异，性别比例对孵化的反应 将检查温度。 如果没有这种遗传变异， 如果当地存在TSD， 温度变化足够迅速， 性别比例 这些研究结果的综合将 阐明TSD的进化意义。

The proposed research is designed to identify factors that account for the adaptive significance of temperature-dependent sex determination (TSD) in reptiles and to assess the impact of environmental conditions on natural populations of reptiles with TSD. The influence of incubation temperature on growth and behavior of juveniles of two species of turtles (common snapping turtles, Chelydra serpentina and spiny softshell turtles, Trionyx spiniferus) will be examined. Correlation of one or both of these traits with incubation temperature and offspring sex would provide the first concrete evidence for the adaptive significance of TSD. The effects of current climatic temperatures on hatchling sex ratios of painted turtles (Chrysemys picta) also will be measured. This project will provide much-needed baseline information on how typical fluctuations in local summer temperatures influence the structure of natural populations with TSD. Additionally, to investigate implications of the predicted global warming on species with TSD, genetic variation, in response of sex ratios to incubation temperature will be examined. Without such genetic variation, species with TSD may be susceptible to extinction if local temperatures change sufficiently and rapidly to greatly skew the sex ratio. The synthesis of the results of these studies will elucidate the evolutionary significance of TSD.