Research Starter Grant: Role of Sex Steroids in Reproductive Timing in Rufous-Collared Sparrows

研究启动资金：性类固醇在红领麻雀繁殖时间中的作用

• 批准号: 0429189
• 负责人: Ignacio Moore
• 金额: $ 5万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2006-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0429189&HistoricalAwards=false
• 关键词: Research; Starter; Grant; Role; Sex

One of the main goals in environmental endocrinology during the last two decades has been to understand the interactions between aggression and sex steroids within males, as modeled by the Challenge Hypothesis. This hypothesis proposes that male-male territorial aggression results in an increase in testosterone levels, which then feeds back to support the aggressive behavior. However, less attention has been focused on the role of sex steroids in male-female social interactions. One area where sex steroids could have a profound effect on male-female interactions is in fine-tuning the timing of breeding within socially monogamous pairs. In tropical birds, breeding seasons are generally long and there is significant variation within the population as to when breeding occurs. This presents an ideal opportunity to elucidate the importance of male-female interactions in the timing of breeding. Previous findings in tropical male rufous-collared sparrows, Zonotrichia capensis, have suggested that male-male interactions do not affect testosterone levels, implying that testosterone is not functioning within the Challenge Hypothesis model. In addition, preliminary data indicate that within monogamous pairs, gonadal state is similar, and independent of the rest of the population. This presents the possibility that male-female interactions may be more important than male-male interactions in determining gonadal activity and testosterone levels. The proposed research will investigate the role of hormonally mediated social cues between males and females in timing of breeding. The following specific questions will be addressed: 1) Within monogamous pairs, is there a correlation between male and female gonadal stage and plasma sex steroid levels? 2) Are hormonally mediated social cues used to fine tune and coordinate reproductive timing within breeding pairs? The results of these studies will clarify the differences documented between high latitude and tropical birds in terms of hormone-behavior interactions. This is important as two-thirds of the world's vertebrates are tropical and thus the typical high-latitude mechanistic relationships may not be adequate to describe them.

在过去的二十年里，环境内分泌学的主要目标之一是了解男性体内攻击性和性类固醇之间的相互作用，就像挑战假说所模拟的那样。这一假说认为，男性对男性的领土攻击会导致睾酮水平的增加，然后睾酮水平会反馈到支持这种攻击行为的水平。然而，人们对性激素在男女社交中的作用关注较少。性激素可能会对男女互动产生深远影响的一个领域是微调社会一夫一妻制伴侣的生育时机。在热带鸟类中，繁殖季节通常很长，种群内对何时发生繁殖有很大的差异。这为阐明雌雄相互作用在繁殖时机中的重要性提供了一个理想的机会。之前在热带雄性红领麻雀Zonotrichia capensis上的发现表明，雄性和雄性之间的相互作用不会影响睾酮水平，这意味着睾酮在挑战假说模型中不起作用。此外，初步数据表明，在一夫一妻制的夫妇中，性腺状态是相似的，并独立于其他群体。这表明，在决定性腺活动和睾酮水平方面，男性和女性之间的互动可能比男性和男性之间的互动更重要。这项拟议的研究将调查荷尔蒙调节的男性和女性之间的社交线索在生育时机中的作用。以下具体问题将被解决：1)在一夫一妻制的配对中，男性和女性的性腺阶段与血浆性类固醇水平之间是否存在相关性？2)荷尔蒙调节的社交线索是否用于微调和协调配对中的生殖时机？这些研究的结果将澄清高纬度鸟类和热带鸟类在荷尔蒙-行为相互作用方面的差异。这一点很重要，因为世界上三分之二的脊椎动物是热带的，因此典型的高纬度机械关系可能不足以描述它们。