Doctoral Dissertation Research: Examining the evolutionary significance of chest patch coloration in a wild primate population

在动物物种中，各种社会和生理线索被认为是向其他个体传达关于个人健康、地位、等级或生殖健康的信息。例如，许多灵长类物种依靠关于其他群体成员的地位和地位的社会线索来衡量竞争力和交配质量，这需要跟踪多个个体的能力。然而，可以识别的个人数量可能有上限。在这个博士论文项目中，研究人员研究了一个群体规模非常大的灵长类物种，以检验男性胸部斑块的颜色是否可以取代排名的社会知识，成为男性竞争能力的信号。该项目直接涉及关于生殖健康的社会和形态指标之间权衡的进化理论，特别是促进关于社会和生态环境的知识，这些环境有利于昂贵的视觉信号(如胸部着色)相对于社会知识的进化，作为评估竞争对手战斗能力的一种手段。在进行拟议的研究时，调查员继续参与当地的公共科学活动，以帮助培养各种背景的年轻学生对科学的兴趣，提高当地社区的科学素养，并促进开放的科学交流，以建立研究人员与公众之间的信任。雄性蜥蜴胸前的彩色斑块被认为是性选择的产物--这是一种抵御潜在竞争对手的优质信号。这项研究从经验上测试了野生狐狸种群中雄性胸色强度、生理和生殖适合度之间的关系。研究人员首先通过分析从个别已知的成年男性拍摄的颜色测量照片来检查可能导致胸部发红的机制，以确定男性发红是否与睾丸激素水平和/或与局部组织血管形成和血流相关的基因表达有关。然后，在功能层面上，调查人员使用人口统计数据和男性个体发红来确定胸部更红是否与这些男性的生殖年限更长有关，以及这是否有助于长期生更多的后代，这是通过对所有婴儿的亲子鉴定确定的。这一裁决反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

In animal species, a variety of social and physiological cues are thought to convey information about an individual’s health, status, rank, or reproductive fitness to other individuals. Many primate species, for example, rely on social cues about status and rank of other group members to gauge competitiveness and mate quality, which requires the ability to keep track of multiple individuals. However, there may be an upper limit to how many individuals can be recognized. In this doctoral dissertation project, the investigator studies a primate species with very large group sizes to examine whether male chest patch coloration may replace social knowledge of rank as a signal of male competitive ability. The project directly engages with evolutionary theories about trade-offs between social and morphological indicators of reproductive fitness, specifically advancing knowledge about the social and ecological environments that favor the evolution of costly visual signals (like chest coloration) relative to social knowledge as a means to appraise fighting ability of competitors. While conducting the proposed research, the investigator continues her involvement in local public science engagement to help foster an interest in science among young students of all backgrounds, improve science literacy in her local community, and promote open science communication to build trust between researchers and the public. The colored patch on the chest of male geladas has been hypothesized to be the product of sexual selection -- a quality signal to ward off would-be rival males. This research empirically tests the relationship between the intensity of male chest color, physiology, and reproductive fitness in a wild population of geladas. The investigators first examine what might cause red chests at a mechanistic level by analyzing color-gauged photographs taken from individually-known adult males to determine if male redness is associated with testosterone levels and/or gene expression related to vascularization and blood flow in the local tissue. At a functional level, the investigators then use demographic data paired with individual male redness to determine whether redder chests are associated with a longer reproductive tenure for those males, and whether this contributes to more offspring in the long-term, as determined by paternity testing of all infants.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.