Testosterone in Female Songbirds: Natural, Sexual, and Correlated Responses to Selection

男性和女性在某些方面是相似的，在其他方面是不同的。 差异的产生可能是因为一种性别受到更大的生殖竞争（性选择）或因为性别在生态学上的差异（自然选择）。 由于男性和女性拥有共同的基因组，他们也会受到相关的选择反应，当一种性别（“有其父必有其子”）受到选择青睐的遗传变异在另一种性别（“有其父必有其子”）中携带沿着时，就会发生这种反应。 如果对一种性别有利的属性对另一种性别不利，那么相关的反应可能会成为进化的限制。类固醇激素是导致性别差异的最接近的机制之一。 它们可能在发育早期组织组织或在生命后期激活性状表达。 当雄性和雌性的激素效应相似时，就有可能对选择做出相关的反应。 这项建议的重点是类固醇激素睾酮（T）和它的整合作用的性别差异的成年男性和女性的鸣禽物种，黑眼junco。 本研究有四个目标。 第一个是通过实验提高女性的睾酮（T），并测量其对女性表型（例如外观，行为）的影响。第二个是要确定是否升高的T是适应或适应不良的女性。 第三个是通过测量暴露于固定剂量的激素刺激剂（GnRH）后T的变化来评估性别内和性别间相关反应的潜力。第四是通过比较T在男性和女性攻击行为激活中的作用来评估性独立。 本提案中所述的研究将为已经令人印象深刻的20年数据库增添内容，为培训未来不同背景的科学家提供机会，开展控制论，以及解决生物差异的近似和最终解释整合的实验室和实地实验。 这一广泛的数据库将为持续的综合、汇编和网络开发提供素材，并将为这位主要研究者的工作、她的合作者以及其他能够接触到这座金矿的人做出重大贡献。 这项网络研究计划也将丰富印第安纳州大学和其他地方的课程。 预期研究结果的潜在社会影响包括：（1）环境中生殖活性物质的影响;（2）更好地理解性与性别之间的关系。

Males and females are similar in some ways and different in others. Differences may arise because one sex is subject to greater reproductive competition (sexual selection) or because the sexes differ in their ecology (natural selection). Because males and females share a common genome, they are also subject to correlated responses to selection, which occur when genetic variants favored by selection in one sex ('like father, like son') are carried along in the other sex ('like father, like daughter'). Correlated responses may serve as an evolutionary constraint if the attributes that are beneficial to one sex are disadvantageous to the other sex. Steroid hormones are among the proximate mechanisms that lead to sex differences. They may act early in development to organize tissues or later in life to activate trait expression. When hormonal effects are similar in males and females, there is potential for correlated responses to selection. The focus of this proposal is the steroid hormone testosterone (T) and its integrating effect on sex differences in adult males and females of a songbird species, the dark-eyed junco. The research has four objectives. The first is to experimentally elevate testosterone (T) in females and measure its effect on the female's phenotype (e.g. appearance, behavior). The second is to determine whether elevated T is adaptive or maladaptive in females. The third is to assess the potential for correlated responses within and between the sexes by measuring change in T after exposure to a fixed dose of a hormonal stimulant (GnRH). The fourth is to assess sexual independence by comparing the role of T in the activation of aggressive behavior in males and females. Research described in this proposal will add to an already impressive 20-year database, provide opportunities for training future scientists of diverse backgrounds in the conduct of cybernetics, and laboratory and field experiments that address the integration of proximate and ultimate explanations for biological differences. This extensive database will provide fodder for continued synthesis, compilation, and cyber exploitation, and will make a significant contribution to this principle investigator's work, her collaborators, and others who will have access to this gold mine. This cyber research program will also enrich courses taught at Indiana University and elsewhere. Potential societal implications of the findings to be expected include: (1) the impact of hormonally active agents in the environment; and (2) a greater understanding of the relationship between sex and gender.