Behavioral and Endocrine Predictors of Reproductive Success in a Cryptically Polygamous Passerine Bird

大多数鸟类以社会一夫一妻制的方式繁殖，但大多数温带繁殖的雀鸟也会在社会伴侣关系之外获得受精。目前尚不清楚为什么雌性会寻求双亲受精，但雌性可能会获得提高后代存活率的“好基因”。雌性如何识别“优质”雄性尚不确定，但已知歌声在某些物种中很重要。在鸟类中，睾丸激素与雄性生殖行为密切相关，包括鸣叫，睾酮的变化可能直接影响雌性对雄性的看法，但本质上，人们对额外配对交配模式和成功的荷尔蒙相关性一无所知。这项研究将研究东方帝王鸟(Tyrannus Tyrannus)额外配对交配成功的行为和激素相关性。Tyrannus Tyrannus是一种社会性一夫一妻制的雀形目鸟类，其中60%的巢包含额外配对的幼鸟。研究人员之前的工作表明，额外配对的成功与歌唱行为直接相关，鉴于歌声是由睾丸素激活和维持的，雄性帝王鸟的睾丸素变化可能与额外配对的成功直接相关。因此，该项目的目标是(A)确定对雌性的额外配对交配行为的益处，(B)描述雄性在整个季节中睾酮的个体差异，(C)测量雄性激素与雌性在择偶过程中似乎使用的行为之间的关系(歌曲)，以及(D)检验生殖成功与睾酮直接相关的假设。这项计划中的研究将解决与身体状况和睾酮的个体差异相关的重要问题，并确定这些差异是否是女性用来识别优质男性的行为的基础。这项拟议的研究将为研究生和本科生提供研究经验，并进一步提供他们从事科学和教学事业的机会，并通过农村高中的在校项目，促进年轻学生的科学事业。

Most birds breed as socially monogamous pairs, yet most temperate zone breeding passerines also acquire fertilizations outside of the social pair bond. It is unclear why females pursue extra-pair fertilizations, but females may acquire "good genes" that enhance offspring survival. How females identify "quality" males is uncertain, but song is known to be important in some species. Testosterone is tightly linked to male reproductive behaviors in birds, including song, and variation of testosterone might directly influence how a male is perceived by a female, but essentially nothing is known of the hormonal correlates extra-pair mating patterns and success. This research will examine the behavioral and hormonal correlates of extra-pair mating success in Eastern Kingbirds (Tyrannus tyrannus), a socially monogamous passerine in which 60% of nests contain extra-pair young. The investigators' previous work has shown that extra-pair success is directly related to song behavior, and given that song is activated and maintained by testosterone, variation of testosterone among male kingbirds is potentially directly related to extra-pair success. Hence, the goals of this project are to (a) identify the benefits to extra-pair mating behavior for females, (b) describe individual variation of testosterone among males over the season, (c) measure the relationship between testosterone and behaviors that females appear to use during mate choice (song), and (d) test the hypothesis that reproductive success is directly related to testosterone. The planned research will address important questions related to individual differences in body condition and testosterone, and determine if these differences underlie the behaviors that females use to identify quality males. The proposed research will provide graduate and undergraduate students with research experiences and further their opportunities to pursue careers in science and teaching, and through in-school programs at rural high schools, promote careers in science among young students.