International Research Fellowship Program: Mammalian Sex Ratios: Linking Adaptive Hypotheses and Physiological Mechanisms

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该项目的奖项提供了联合研究的机会，并利用国外独特或互补的设施、专业知识和实验条件。该奖项将支持丽莎·施万茨博士与澳大利亚詹姆斯·库克大学的克里斯托弗·约翰逊博士合作的为期24个月的研究奖学金。后代性别比例在人群和个人之间存在显著差异。性别比理论是进化生物学的基石，旨在解释后代性别比的多样性。该理论取得了显著的成功，在多种生物学情景中预测了后代的性别比例，从而将自然选择确立为生殖多样性进化的重要机制。后代性别比的重要性超越了理论，几乎延伸到种群生物学的方方面面，包括社会行为、种群动态和保护。鸟类和哺乳动物的性别比没有像在其他分类群中那样被成功预测，这仍然是性别比理论的下一个巨大挑战。这项研究将建立在最近的概念进展的基础上，通过在适应性和机械性水平上调查一种具有保护意义的澳大利亚本土哺乳动物的哺乳动物性别比例。这项研究的主要目的是同时测试最近关于哺乳动物性别比偏差的机械假说，并研究多种环境条件如何通过后代的交配影响母亲的健康。具体地说，这项研究将利用Tammar袋鼠的有袋类生物学来测试母体血液皮质醇和葡萄糖在后代性行为中的作用，并解开与两个性别分配假说--特里弗斯-威拉德假说和当地资源竞争假说--相关的选择压力的潜在同时运行。后代性交的健康后果将通过通过性别交叉养育后代来揭示，这项技术从未在哺乳动物性别比研究中发表过。这项研究将推动哺乳动物性别比例研究的两个前沿？适应性解释和近似性机制。通过将生理分析与野外观测数据和野外操作相结合，本研究将解决生态学和进化生物学交界处的一个重要问题。这一博士后奖学金将涉及与澳大利亚多名研究人员和机构的合作，并为美国和澳大利亚科学家之间的长期研究合作奠定基础。研究结果将有助于更好地了解哺乳动物后代性别比例的发生和性质，并对保护(例如圈养繁殖)和害虫管理具有重要意义。此外，这项研究将涉及对澳大利亚学生和非学术志愿者进行实地研究和实验科学方面的培训。

0754299SchwanzThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four month research fellowship by Dr. Lisa Schwanz to work with Dr. Christopher Johnson at James Cook University in Australia.Offspring sex ratios vary remarkably among populations and individuals. Sex ratio theory is a cornerstone of evolutionary biology that aims to explain the diversity of offspring sex ratios. The theory has seen remarkable success, predicting offspring sex ratios in a multitude of biological scenarios, thus establishing natural selection as an important mechanism in the evolution of reproductive diversity. The importance of offspring sex ratios extends beyond theory to nearly every aspect of population biology, including social behavior, population dynamics and conservation. Sex ratios of birds and mammals have not been as successfully predicted as in other taxa, and remain the next great challenge for sex ratio theory. This research will build on recent conceptual advances by investigating mammalian sex ratios at an adaptive and mechanistic level in a native Australian mammal of conservation interest. The primary objective of the research is to simultaneously test a recent mechanistic hypothesis for sex ratio biases in mammals and examine how multiple environmental conditions impact maternal fitness through offspring sex. Specifically, the research will take advantage of the marsupial biology of the Tammar wallaby to test for the roles of maternal blood cortisol and glucose in offspring sex and untangle the potentially simultaneous operation of selective pressures associated with two hypotheses of sex allocation, the Trivers-Willard and Local Resource Competition hypotheses. The fitness consequences of offspring sex will be revealed through cross-fostering of offspring by sex, a technique that has never been published in mammalian sex ratio research. This research will advance the two frontiers of research in mammalian sex ratios ? the adaptive explanations and the proximate mechanisms. By integrating physiological assays with field observational data and field manipulations in wild marsupial populations, this research will address an important question at the interface of ecology and evolutionary biology. This postdoctoral fellowship will involve collaboration with multiple researchers and institutions in Australia and form the basis for long-term research collaborations between US and Australian scientists. The results of the research will provide a greater understanding of the occurrence and nature of offspring sex ratios in mammals, and have strong implications for conservation (e.g. captive breeding) and pest management. In addition, the study will involve training of Australian students and non-academic volunteers in field research and experimental science.