Early birds and extra-pair mates: Do nightly peaks of steroid hormones influence onset of daily behaviors and opportunities for extra-pair mating?

几乎所有的生物体，从细菌到人类，都表现出生理和行为的日常变化。然而，个体的日常节律存在很大的差异；一些个体自然地很早开始他们的日常活动(例如早晨的云雀)，而另一些人则开始他们的日常活动较晚(例如夜猫子)。导致个体间这些差异的生物学原因以及行为节律与其他重要生物过程之间的关系仍未完全清楚。生殖类固醇激素(如睾酮和雌激素)在调节许多生殖相关行为方面发挥着重要作用。血液中这些荷尔蒙的水平也显示出每日的节律。这项研究使用一只欧亚空巢鸣鸟(即在森林中提供的盒子里很容易筑巢)来检验这一假设，即这些激素的水平和节律在个体之间的差异可能会影响日常行为模式和繁殖成功。在世界许多地区，城市化的生活方式正在改变人类和非人类动物的日常活动节奏。这项研究将深入了解影响这些节律的机制，以及这些节律如何影响物种的持久性。这些信息对于提供解决人类引起的动物节律改变的原因和后果的未来问题所需的基线知识至关重要。该项目将与一名德国同事合作进行，并将为博士后助理、研究生和本科生提供国际培训机会。调查人员积极参与面向公众的科学宣传，包括科学家与部落大学生和教员之间的文化和知识交流。荷尔蒙调节着一系列与健康有关的特征。类固醇激素(如雌二醇和睾酮)在循环水平上表现出昼夜节律变化。这些荷尔蒙也已知与实验室动物的昼夜节律系统相互作用。关于每天(白天和晚上)荷尔蒙峰值与重要日常行为或健康的时间安排之间的关系，我们知之甚少。在鸣禽中，额外的交配通常发生在黎明前，最早起床的人最成功，这表明日常行为节律以及驱动它们的机制可能对个体健康有重要影响。利用一种欧亚空巢鸣鸟(Parus Main)，这项研究将(1)确定每日类固醇浓度的自然变化与行为节律之间的关系。(2)实验验证类固醇循环水平影响昼夜行为(活动开始和黎明歌声)表达的假设。(3)量化每日节律、峰值激素水平和生殖成功之间的关系。为了达到这些目标，将通过使用自动遥测记录系统，结合行为观察和巢箱上的射频识别器(RFID)阅读器来量化日常行为节律。荷尔蒙将在夜间采集的候鸟产卵前和白天的血液样本中进行测量。激素操作将用于实验研究，对节律和生殖成功的影响将被记录在案。繁殖成功将通过监测繁殖种群中的所有巢穴和遗传亲子关系分析来量化。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Nearly all organisms, from bacteria to humans, display daily changes in physiology and behavior. Yet, substantial variation among individual daily rhythms exist; some individuals naturally begin their daily activity early (e.g. morning larks) while some begin their daily activity later (e.g. night owls). The biological reasons that lead to these variations among individuals and the relationships between behavioral rhythms and other important biological processes is still not fully understood. Reproductive steroid hormones (e.g. testosterone and estrogens) play an important role in regulating many reproductive related behaviors. The level of these hormones in blood also display daily rhythms. Using a Eurasian, cavity nesting songbird (i.e. readily nests in boxes provided in the forest), this research will test the hypothesis that variation between individuals in the levels and rhythms of these hormones may be influencing daily behavioral patterns and reproductive success. In many areas of the world an urbanized life-style is leading to altered daily activity rhythms of both human and non-human animals. This study will provide insight into the mechanisms that influence these rhythms and how these rhythms influence the persistence of species. Such information will be vital for providing baseline knowledge needed to address future questions of the causes and consequences of human-induced alterations of animal rhythms. This project will be conducted in collaboration with a German colleague and will provide opportunities for international training of postdoctoral associates, graduate and undergraduate students. The investigators are actively involved in scientific outreach to public audiences, including cultural and knowledge exchange between scientists and tribal college students and instructors. Hormones regulate a wide variety of traits that have been linked with fitness. Steroid hormones (e.g. estradiol and testosterone) display circadian variations in circulating levels. These hormones are also known to interact with the circadian system in lab animals. Little is known about how daily (daytime and nightly) peaks of hormones are linked to the timing of important daily behaviors or fitness. In songbirds, extra-pair copulations often occur during the pre-dawn period with the earliest risers having greatest success, suggesting that daily behavioral rhythms, and the mechanisms driving them may have important implications for individual fitness. Using a Eurasian cavity nesting songbird (Parus major) this research will (1) Identify relationships between natural variation in daily steroid concentrations and behavioral rhythms. (2) Experimentally test the hypothesis that circulating levels of steroids influence the expression of circadian behaviors (onset of activity and dawn song). (3) Quantify the relationship between daily rhythms, peak hormone levels, and reproductive success. To address these aims, daily behavioral rhythms will be quantified through the use of an automated telemetry recording system, combined with behavioral observations and Radio-Frequency ID (RFID) readers on nest boxes. Hormones will be measured in blood samples collected at night from roosting birds in the pre-laying period as well as during the day. Hormone manipulations will be employed for experimental studies, and effects on rhythms and reproductive success will be documented. Reproductive success will be quantified via monitoring of all nests in a breeding population and genetic parentage analysis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.