海南睑虎温度决定性别的生理基础

Temperature-dependent sex determination (TSD) is a mechanism adopted by all crocodiles and turturas, many turtles and some lizards to determine the sexual phenotype of their offspring, and has been an important topic of reptile studies over the past decades. The underlying physiological mechanism for the phenomenon is still poorly studied in any reptile taxa with TSD. We will use the Hainan leopard gecko (Goniurosaurus lichtenfelderi hainanensis), a nocturnal species living in dense tropical forests, as the model system to study the physiological and molecular mechanisms for TSD in reptiles. We wll measure yolk steroid hormones such as E2 (17 beta-estradiol), DHT (Dihydrotestosterone) and T (Testosterone) to show whether changes in these hormones around the temperature sensitive period (TSP) have a role in influencing offspring phenotypes (sex, body size, morphology, locomotor performance, growth, survival and reproduction for the first time). We will measure yolk E2, DHT and T levels of eggs laid by females with body temperatures set at 20, 22, 24, 26 and 28 ℃ and by females thermoregulating in the field and laboratory to show whether the possible thermal dependence of maternal allocation of yolk steroid hormones has a role in influencing offspring phenotypes. We will measure yolk E2, DHT and T levels of eggs incubated at 20, 22, 24, 26 and 28 ℃to show whether incubation temperature and temperature-induced variation in yolk steroid hormones have a role in influencing offspring phenotypes. Because ectotherms living in tropical forests, especially nocturnal species with TSD, are highly vulnerable to climate warming on a global scale, studies that quantify the temperature effetcs on field populations must be a high priority for this group of animals. The Hainan leopard gecko is recently found to be a TSD species where female-biased hatchlings are produced at low or high incubation temperatures and male-biased hatchlings are produced at intermediate incubation temperatures, and is well suited to this study. This project is of particular importance in uncovering the physiological basis and the adaptive significance of the evolution of TSD in warm-climate nocturnal lizards.

温度依赖的性别决定（TSD）见于所有鳄类和楔齿蜥、许多龟鳖和部分蜥蜴,是爬行动物研究的重要内容之一，但爬行动物TSD决定性别的生理基础迄今尚不清楚。本项目拟以热带森林的夜行性海南睑虎为材料探讨TSD的生理基础。拟通过测定孵化卵的卵黄E2、T和DHT含量，分析性别决定敏感期及其前后这些激素含量变化与后代表型（性别、个体大小、形态、运动表现、生长、存活率、首次繁殖等）的关系；拟测定20-28℃范围内不同体温雌体，以及野外和实验室调温雌体所产新生卵的卵黄E2、T和DHT含量，检测母体卵内类固醇激素分配的热依赖性及其对后代表型的影响；拟测定20-28℃范围内不同孵化温度下性别决定敏感期及其前后卵黄E2、T和DHT含量，研究孵化温度和类固醇激素变化对后代表型的影响。本项目对于阐述温暖气候区夜行性蜥蜴TSD的生理基础和进化适应意义具有重要价值。