LTREB: Long-term Research on Environmental Gender Determination in a Model System (Chrysemys)

与大多数脊椎动物的性别决定机制相反，许多爬行动物的性别是由胚胎发育期间的环境温度决定的。这种性别决定系统的不寻常性质，具有产生强烈偏见的性别配给的潜力，已经引起了人们对其进化起源和生物学意义的极大兴趣。尽管如此，人们对这种温度依赖性性别决定（TSD）的许多方面的重要性知之甚少，这些方面可能有助于深入了解这些基本问题。特别是，长期的气候变化对关键的人口统计参数，即后代和人口性别比的影响，目前还不清楚与TSD爬行动物。此外，巢址选择在这个系统中的作用几乎是未被探索的，特别是在这些类群的特点是长的生殖寿命，尽管它的意义在大多数理论模型的性别比例进化。捕食，偏见或其他，也占据了重要的作用，在种群动态的理论模型，但其对后代性别比的影响是未知的。具有TSD的生物体是探索这些主要因素对自然界种群动态和性比进化的影响的理想模型系统。 拟议的LTREB研究将调查TSD的进化生态学的几个重要方面，在一个自然种群的长寿彩龟，这已详细研究自1988年以来。首先，长期气候变化如何与年度队列性别比协变，从而影响人口统计学和TSD的演变？第二，女性TSD表现出长期的个体遗传重复性的nst网站的选择相对于可用的热环境，从而提供了一个目标的进化反应的性别比选择所施加的快速气候变化和人类栖息地改造？第三，什么是长期的时空动态的巢捕食和后代的性比在一个自然的人口与TSD和因此他们的影响，人口统计学和性比的演变？鉴于气候变化和人类生境的迅速改变，获得这些问题的答案变得更加紧迫。

0089680JanzenIn contrast to the sex-determining mechanisms of most vertebrates, sex in many reptiles is determined by environmental temperatures determined during embryonic development. The unusual nature of this sex-determination system, with its potential to produce strongly-biased sex rations, has generated considerable interest in its evolutionary origin and biological significance. Nonetheless, little is understood about the importance of many aspects of this temperature-dependent sex determination (TSD) that could lend insight into these fundamental questions. In particular, the impact of long-term climatic variation on crucial demograpic parameters, namely offspring and population sex ratios, is unclear in reptiles with TSD. Furthermore, the role of nest-site choice in this system is virtually unexplored, especially across the long reproductive lifespans that characterize these taxa, despite its significance in most theoretical models of sex-ratio evolution. Predation, biased or otherwise, also occupies a significant role in theoretical models of population dynamics but its impact on offspring sex ratio is unknown. Organisms with TSD are ideal model systems with which to explore the impact of these major factors on population dynamics and sex-ratio evolution in nature. The proposed LTREB research will investigate several significant aspects of the evolutionary ecology of TSD in a natural population of long-lived painted turtles, which has been studied in detail since 1988. First, how does long-term climatic variation covary with annual cohort sex ratio and thus influence population demography and the evolution of TSD? Second, do females with TSD exhibit long-term ontogenetic repeatability of nst-site choice with respect to available thermal environments and thereby provide a target for evolutionary response to sex-ratio selection imposed by rapid climate change and human habitat modification? Third, what are the long-term spatio-temporal dynamics of nest predation and offspring sex ratio in a natural population with TSD and thus their impacts on population demography and sex-ratio evolution? Obtaining answers to such questions assumes greater urgency given rapid climate change and human habitat modification.