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

LTREB：模型系统中环境性别决定的长期研究（Chrysemys）

• 批准号: 0089680
• 负责人: Fredric Janzen
• 金额: $ 29.45万
• 依托单位: Iowa State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-01 至 2007-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0089680&HistoricalAwards=false
• 关键词: LTREB; Long; term; Research; Environmental

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.

[00:8968 . 80]与大多数脊椎动物的性别决定机制不同，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，以及它可能产生强烈偏见的性别配给，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，而这些方面可能有助于深入了解这些基本问题。特别是，长期气候变化对患有TSD的爬行动物的关键人口参数（即后代和种群性别比）的影响尚不清楚。此外，尽管巢址选择在性别比进化的大多数理论模型中具有重要意义，但它在这一系统中的作用实际上尚未被探索，特别是在这些分类群的长生殖寿命特征中。在种群动态的理论模型中，有偏向或无偏向的捕食行为也占有重要地位，但其对后代性别比的影响尚不清楚。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别比进化影响的理想模型系统。自1988年以来，人们对长寿命彩绘龟自然种群的TSD进行了详细的研究，提出的LTREB研究将调查该种群中TSD进化生态学的几个重要方面。首先，长期气候变化如何与年度队列性别比例协同变化，从而影响人口统计学和TSD的演变？其次，相对于可用的热环境，患有TSD的雌性是否表现出长期的巢址选择的个体发生可重复性，从而为快速气候变化和人类栖息地改变所施加的性别比例选择的进化反应提供了一个目标？第三，创伤后应激障碍自然种群的巢捕食和后代性别比的长期时空动态及其对种群人口统计学和性别比演化的影响。鉴于气候的迅速变化和人类栖息地的改变，找到这些问题的答案显得更加紧迫。