Dissertation Research: Temperature Dependent Sex Determination in the Giant River Turtle Podocnemis Expansa from Colombian Amazonia

论文研究：哥伦比亚亚马逊河巨龟 Podocnemis Expansa 的温度依赖性性别决定

• 批准号: 9800679
• 负责人: Charles Janson
• 金额: $ 0.84万
• 依托单位: SUNY at Stony Brook
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-15 至 2000-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9800679&HistoricalAwards=false
• 关键词: Dissertation; Research; Temperature; Dependent; Sex

Janson 9800679 Unlike mammals and birds, embryos of many turtle species can develop into either sex, depending on the temperature at which they are raised. As a rough rule, high temperatures during a particular sensitive period induce differentiation into females and low temperatures induce males. The purpose of this proposal is to model temperature-dependent sex determination of the endangered Amazonian Giant River Turtle, Podocnmeis expansa. Unlike previous efforts, this new model will include natural fluctuations of temperature as experienced in the field, as well as controlled laboratory experiments. The following specific experiments will be conducted: 1) Artificial incubation at constant temperatures; 2) Shift-one and shift-twice experiments, where eggs are transferred from female to male-producing temperatures and vice versa; 3) Seminatural incubation at different depths and shade conditions, and natural incubation. With these experiments the PIs will determine the relationship of sex ratios to temperature, the timing of the temperature-sensitive period of development, and the effects of fluctuating temperatures on sex ratios. The PIs will propose that the single variable underlying all these relationships is the amount of heat accumulated by the end of the sensitive period. The PIs will measure accumulated heat under different experimental and natural incubation regimes and relate this variable to rate of development and hatchling sex ratios. The results should provide a model that explains sex-ratios in nature for turtles in general, and will be useful in designing management plans for this endangered study species.

Janson 9800679 与哺乳动物和鸟类不同，许多海龟物种的胚胎可以发育成任何一种性别，这取决于它们被饲养的温度。 作为一个粗略的规则，高温在特定的敏感期诱导分化成女性和低温诱导男性。 这项建议的目的是模拟温度依赖的性别决定的濒危亚马逊河巨龟，Podocnmeis expansa。 与以前的努力不同，这个新模型将包括现场经历的自然温度波动，以及受控的实验室实验。 将进行以下具体实验：1）恒温人工孵育; 2）移一和移两次实验，其中将卵从雌性转移到雄性生产温度，反之亦然; 3）在不同深度和阴凉条件下的半自然孵育，以及自然孵育。 通过这些实验，PI将确定性比与温度的关系，发育的温度敏感期的时间，以及温度波动对性比的影响。 PI将提出，所有这些关系背后的单一变量是敏感期结束时积累的热量。 PI将在不同的实验和自然孵化制度下测量累积的热量，并将此变量与发育速度和孵化的性别比例联系起来。 研究结果应该提供一个模型，解释性别比例在自然界中的海龟一般，并将有助于设计管理计划，为这一濒危物种的研究。