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

在动物物种中，各种各样的社会和生理线索被认为可以向其他个体传递有关个体健康、地位、等级或生殖适应性的信息。例如，许多灵长类动物依靠关于其他群体成员地位和等级的社会线索来衡量竞争力和配偶质量，这需要跟踪多个个体的能力。然而，可以识别的个体数量可能有上限。在这个博士论文项目中，研究者研究了一个群体规模非常大的灵长类物种，以研究雄性胸斑颜色是否可以取代社会等级知识作为雄性竞争能力的信号。该项目直接涉及关于生殖适应性的社会和形态指标之间权衡的进化理论，特别是关于社会和生态环境的知识，这些知识倾向于进化昂贵的视觉信号（如胸部颜色），而不是社会知识，作为评估竞争对手战斗力的手段。在进行拟议的研究的同时，研究者继续参与当地的公共科学参与，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。雄性狒狒胸前的彩色斑块被认为是性选择的产物——一种抵御潜在竞争对手的质量信号。本研究对野生狒狒种群雄性胸部颜色强度、生理和生殖健康之间的关系进行了实证检验。研究人员首先通过分析从个别已知的成年男性身上拍摄的彩色照片，在机制层面上检查可能导致胸部发红的原因，以确定男性发红是否与睾丸激素水平和/或与局部组织血管化和血流相关的基因表达有关。在功能层面上，研究人员使用人口统计数据与个体男性的红色配对，以确定这些男性的较红的胸部是否与较长的生殖期有关，以及这是否有助于在长期内产生更多的后代，这是通过对所有婴儿的亲子鉴定来确定的。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识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.