International Research Fellowship Program: Fitness Cost and Neuroendocrine Correlates of Premature Breeding

0852986 Greives该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。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。 该计划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。该奖项将支持蒂莫西·J·格雷夫斯博士与德国马克斯·普朗克鸟类学研究所的Michaela Hau博士和加州大学的Tom Hahn博士进行为期24个月的研究。几乎所有的动物，包括鸟类，都可以观察到生殖活动的季节性周期。这些周期代表了在有利的环境条件下确保后代生产的适应性。在温带，光周期（即，日长）提供了一个？没有噪音吗一个季节性的线索，每年的某一天都是一样的。因此，大多数物种依靠光周期来确定一年中的时间。繁殖的季节性变化甚至在生活在相对稳定的栖息地的物种中得到了证明（即，热带），这表明选择有利于跨纬度的生殖活动的季节性调节。然而，脊椎动物性腺周期的选择压力的性质仍然未知。这部分是由于方法上的限制，限制了在实验上修改性腺激活时间的能力。 该奖学金测试的假设，繁殖的精确时间已经演变为健身成本与不合时宜的繁殖事件。 在自由生活的大山雀中，通过使用附着在鸟类身上的微型发光二极管（LED）操纵感知光周期，性腺激活的时间正在提前？头部，在正常性腺发育开始之前提供光周期刺激。此外，不适时的繁殖对新的神经肽（例如，kisspeptin，促性腺激素抑制激素）的研究，这将有助于更好地了解它们在调节脊椎动物生殖方面的具体作用。 在实验1中，行为，繁殖成功率和存活率被记录在育种对。在实验2中，神经内分泌反应早熟光周期刺激将使用国家的最先进的技术进行研究。拟议的实验是第一个使用光周期操纵在自由生活的脊椎动物，以量化对健身的影响，以推进性腺发育。了解选择压力，作用于不合时宜的季节性过程将有助于解决为什么大多数鸟类物种，以及世界各地的大量脊椎动物，在性腺大小表现出明显的周期性的问题。它们还将提供一个独特的机会来阐明各种环境线索在大脑中整合的机制。所产生的知识将有助于了解影响种群和物种应对全球气候变化或向新生境扩散的能力的基本过程（最终和近期）。

0852986GreivesThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The 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. Timothy J. Greives to work with Dr. Michaela Hau at Max Planck Institute for Ornithology in Germany and with Dr. Tom Hahn at the University of California, Davis in the US.Seasonal cycles in reproductive activity are observed in virtually all animals, including birds. These cycles represent adaptations that ensure offspring production during favorable environmental conditions. In the temperate-zone, photoperiod (i.e., day-length) provides a ?noise-free? seasonal cue that does not vary from year to year for a given day. Hence, most species rely on photoperiod to determine the time of year. Seasonal changes in reproduction have even been demonstrated in species living in relatively stable habitats (i.e., the tropics), suggesting that selection favors a seasonal regulation of reproductive activity across latitudes. However, the nature of the selection pressures that shape gonadal cycles in vertebrates remains unknown. This has been due, in part, to methodological constraints limiting the ability to modify experimentally the timing of gonad activation in the field. This fellowship tests the hypothesis that the precise timing of reproduction has evolved in response to fitness costs associated with mistimed breeding events. The timing of gonadal activation is being advanced in free-living great tits through manipulation of perceived photoperiod using a miniature light emitting diode (LED) attached to the birds? head, providing photoperiodic stimulation prior to the start of normal gonadal development. Further, the effect of mistimed reproduction on novel neuropeptides (e.g., kisspeptin, gonadotropin-inhibitory hormone) is being examined; this will enable a better understanding of their specific roles in regulating vertebrate reproduction. In Experiment 1, behavior, reproductive success and survival rates are being documented in breeding pairs. In Experiment 2, neuroendocrine responses to precocious photoperiodic stimulation will be investigated using state-of-the-art techniques. The proposed experiments are the first to advance gonadal development using photoperiod manipulation in a free-living vertebrate to quantify resulting effects on fitness. Understanding the selection pressures that act on mistimed seasonal processes will help to resolve the question of why most avian species, and a large number of vertebrates world-wide, exhibit pronounced cycles in gonad size. They will also provide a unique opportunity to elucidate mechanisms by which diverse environmental cues are integrated within the brain. The knowledge generated will be useful in understanding the underlying processes (both ultimate and proximate) shaping the ability of populations and species to respond to global climate change or spread to new habitats.