Maternal Effects as Mechanisms for Variation in Development rate ? A Study of Life Histories in Tropical and North Temperate Passerine Birds

母体效应作为发育速度变化的机制？

• 批准号: 0745330
• 负责人: Hubert Schwabl
• 金额: $ 45.85万
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-05-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0745330&HistoricalAwards=false
• 关键词: Maternal; Effects; Mechanisms; Variation; Development

Most (~75%) vertebrate species of the world inhabit tropical and southern hemisphere regions, and are generally characterized with a 'slow' development rate. North temperate species, in contrast, generally posses a 'fast' development rate. This project will combine controlled comparative analyses with manipulative experiments to examine whether epigenetic maternal effects, mediated by maternal hormones, are proximate mechanisms causing the variation of development rate and related life history strategies across latitudes. It explores and experimentally tests the hypotheses that variation in exposure of the avian embryo to maternally derived hormones in the egg explains variation in offspring development rate. Maternal hormones selected for study are: i) androgens because they show strong correlations with development rate in temperate zone passerines; and ii) thyroid hormones because they are regulators of vertebrate development and metabolism. The hypothesis predicts these egg hormones i) to be lower in tropical than temperate passerines; ii) to cause variation in rate of embryo development; iii) to cause trade-offs between development rate and offspring quality such as immune function, thereby explaining variation in other life history traits as well. Proposed studies will be conducted in conjunction with ongoing long-term investigations conducted by Dr. Thomas Martin (U. Montana) that address the ultimate causes (e.g. offspring and parent mortality) of variation in development rate in the same model systems with a tight integration of projects and approaches. This will provide a powerful and unique tool for testing hypotheses of evolution of life histories, generating novel and critical insights into epigenetic maternal effects on life history evolution and evaluating selection pressures driving evolution of proximate mechanisms of maternal effects in both the parent (reproductive physiology) and the offspring (developmental physiology) generations. The project provides training of graduate and undergraduate students in integrative approaches to, and analyses of, complex biological questions.

世界上大多数（〜75％）的脊椎动物物种居住在热带和南半球地区，通常以“缓慢”的发展速率进行特征。 相比之下，北温带物种通常具有“快速”的发展速度。该项目将将受控的比较分析与操纵实验相结合，以检查由母体荷尔蒙介导的表观遗传母体效应是否是导致纬度跨纬度的发展速率和相关生活历史策略变化的近端机制。它探索并通过实验测试了卵子中禽类胚胎暴露于母体衍生的激素的假设解释了后代发展速率的差异。选择进行研究的母体激素是：i）雄激素，因为它们与温带雀形的发育速率显示强相关； ii）甲状腺激素是因为它们是脊椎动物发育和代谢的调节剂。该假设预测这些卵激素i）在热带中比温带雀形成低； ii）导致胚胎发育速率变化； iii）在发展速度和后代质量（例如免疫功能）之间进行权衡，从而解释了其他生活历史特征的差异。拟议的研究将与托马斯·马丁（U. Montana）博士（U. Montana）进行的持续的长期研究一起进行，该研究涉及在同一模型系统中的最终原因（例如后代和父母的死亡率）与紧密整合的相同模型系统中的变化项目和方法。这将为测试生命历史进化的假设提供强大而独特的工具，从而产生对表观遗传孕产妇对生活历史的影响的新颖和批判性见解，并评估选择压力推动了母体效应的邻近机制的进化（生殖生理学）以及后代（发展生理）的世代。该项目为研究生和本科生提供了综合方法和分析复杂生物学问题的培训。