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

0852986格雷斯该奖项由2009年美国复苏和再投资法案(公法111-5)资助。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至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Timothy J.Greives博士与德国马克斯·普朗克鸟类学研究所的Michaela Hau博士和美国加州大学戴维斯分校的Tom Hahn博士合作，为期24个月的研究奖学金。几乎所有动物，包括鸟类，都观察到繁殖活动的季节性周期。这些循环代表了在有利的环境条件下确保后代生产的适应。在温带，光周期(即日长)提供了一个无噪声的环境。对于给定的一天，不随年年变化的季节性提示。因此，大多数物种依靠光周期来决定一年中的时间。甚至在生活在相对稳定的栖息地(即热带)的物种中也表现出繁殖的季节性变化，这表明选择有利于跨纬度繁殖活动的季节性调节。然而，影响脊椎动物性腺周期的选择压力的性质仍不清楚。这在一定程度上是由于方法学上的限制，限制了在野外试验性地修改性腺激活时间的能力。这种团契关系检验了这样一个假设，即繁殖的准确时间是随着与错误的繁殖事件相关的健康成本而演变的。通过使用连接在鸟类身上的微型发光二极管(LED)来操纵感知的光周期，自由生活的大山雀性腺激活的时间正在提前？头部，在性腺开始正常发育之前提供光周期刺激。此外，错误的繁殖时机对新神经肽(如Kispeptin、促性腺激素抑制激素)的影响正在研究中；这将使人们更好地了解它们在调节脊椎动物繁殖方面的具体作用。在实验1中，行为、繁殖成功率和存活率是在配对繁殖中记录下来的。在实验2中，将使用最先进的技术来研究神经内分泌对早熟光周期刺激的反应。拟议中的实验是第一次利用光周期操作在自由生活的脊椎动物中促进性腺发育，以量化由此产生的对健康的影响。了解作用于错误的季节性过程的选择压力，将有助于解决为什么大多数鸟类和世界各地的大量脊椎动物在性腺大小上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不同的环境线索在大脑中整合的机制。所产生的知识将有助于理解形成种群和物种应对全球气候变化或扩散到新栖息地的能力的潜在过程(包括最终和最近的)。

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.