DISSERTATION RESEARCH: Coordination of testosterone-mediated phenotypes and underlying endocrine mechanisms across divergent populations of the dark-eyed junco (J. hyemalis)

激素同时调节植物和动物的许多性状，从而协调大小，生理和行为的表达。当环境发生变化或新的环境被殖民时，激素对性状的这种共同控制可能会也可能不会促进对改变的环境的适应，这取决于激素控制的细节。在脊椎动物中，激素睾酮（T）对与生殖有关的性状特别重要，如顺从和侵略。 T对性状的共同控制可以通过保留有利的组合（例如，攻击性与防御性相结合，以同时阻止竞争对手和吸引配偶）或延迟适应，如果一个潜在的有益性状的控制被激素与另一个有害性状联系在一起。这种相互作用对物种进化和应对气候变化具有重要意义，但令人惊讶的是，我们对其实际性质知之甚少。该项目将支持现场和实验室研究，以解决T和在鸣禽的一个亚种中观察到的各种行为和形态特征之间的关系，黑眼junco，可以用来预测生活在非常不同的环境中的另一个亚种中的相同关系。该项目还将研究可能导致这些关系中潜在差异的潜在生理机制，询问它们是否在个体和亚种之间存在差异。具体来说，对圈养鸟类的激素操纵和神经研究将检查触发T释放的激素级联，以及影响T对性状影响的激素受体。跨亚种的T、性状和生理机制之间的一致共变将表明激素系统作为一个单位进化。或者，种群间缺乏相似性将表明独立进化的潜力很大，允许激素系统更自由或更不一致地分化。 这项研究将为不同的本科生提供许多有效的指导机会，研究结果有望有助于了解激素系统的进化。

Hormones simultaneously mediate numerous traits of plants and animals thus coordinating expression of size, physiology and behavior. When environments change or new environments are colonized, this common control of traits by hormones may or may not facilitate adaptation to the altered environment, depending on the details of hormonal control. In vertebrate animals, the hormone testosterone (T) has particular importance for traits related to reproduction, such as ornamentation and aggression. The common control of traits by T may facilitate adaptation by preserving favorable combinations (e.g., aggression coupled with ornamentation to simultaneously deter rivals and attract mates) or delay adaptation if control of a potentially beneficial trait is linked by the hormone to another trait that would be detrimental. This interplay has important implications for species evolution and response to climate change, yet we know surprisingly little about its actual nature. This project will support field and laboratory research to address whether relationships between T and various behavioral and morphological traits observed in one sub-species of a songbird, the dark-eyed junco, can be used to predict the same relationships in another subspecies that lives in a very different environment. The project will also examine the underlying physiological mechanisms that may contribute to potential differences in these relationships, asking whether they vary among individuals and subspecies. Specifically, hormone manipulations and neural studies with captive birds will examine hormonal cascades that trigger T release, as well as hormone receptors that affect T's influence on traits. Consistent co-variation between T, traits, and physiological mechanisms across subspecies will suggest that hormone systems evolve as a unit. Alternatively, absence of similarity across populations will suggest high potential for independent evolution, allowing hormone systems to diverge more freely or less consistently. The research will provide numerous opportunities for effective mentorship of diverse undergraduates, and the findings are expected to contribute to an understanding of hormone system evolution.