Doctoral Dissertation Research: The energetics of male reproductive strategies in geladas

在灵长类动物的生殖生态学中，能量作为生殖约束的作用通常集中在雌性身上。然而，在包括人类在内的哺乳动物中，雄性的繁殖努力往往会带来巨大的代谢成本。这个博士论文项目将研究能量如何限制野生灵长类动物狒狒的雄性行为和繁殖。该项目将深入了解动物生理和生殖努力如何适应自然生态变化，并研究雄性生殖行为的调节机制睾丸激素如何直接受到能量的限制。通过研究能量学对非人类灵长类动物睾丸激素介导的生殖努力分配的影响，该项目将揭示能量学在塑造非人类灵长类动物和古人类物种中的选择压力和潜在影响。通过这项研究，Co-PI将为来自STEM领域中代表性不足的群体的本科生提供基于实验室的行为内分泌学技术培训。此外，协作团还将在国内外各场所开展科学教育和保护宣传活动。该项目将以野生狒狒为研究对象，通过雄性狒狒在雄性狒狒竞争中使用的声音和视觉信号来评估雄性狒狒的能量状态、生理和雄性品质之间的关系。为此，该项目将结合经典的行为观察和创新的方法(1)数字摄影测量来评估男性胸部斑块的颜色，(2)内分泌学来确定非侵入性收集的尿液和粪便样本的能量状况。狒狒的一夫多妻制交配系统为研究雄性生殖能量的差异提供了一个理想的模型：后宫制狒狒领导雄性繁殖绝大多数后代，而全雄性群体中的单身雄性缺乏繁殖机会。因此，繁殖成功在很大程度上倾向于雄性狒狒领袖，单身狒狒必须在充满能量挑战的“接管”事件中推翻领导者，以获得与雌性狒狒繁殖的机会。本研究将评估男性能量状态的潜在季节性变化，这种变化与男性社会地位的关系，以及能量状态是否最终限制了睾丸激素依赖信号和男性生殖策略。尽管有充分的证据表明，较低的食物供应和能量可能会限制雄性生殖生理，但需要对雄性灵长类动物的睾丸激素、能量和生殖之间的相互关系进行全面的了解。这项研究将是首次评估能量如何成为野生灵长类动物雄性繁殖成功的限制因素之一。

In primate reproductive ecology, the role of energy as a constraint on reproduction has often focused on females. Yet across mammals, including humans, male reproductive effort can often entail substantial metabolic costs. This doctoral dissertation project will examine how energy constrains male behavior and reproduction in a wild primate, the gelada monkey. The project will provide insight into how animal physiology and reproductive efforts adjust to natural ecological change, and examine how testosterone, a regulatory mechanism for male reproductive behavior, may be directly limited by energy. By examining the effects of energetics on the allocation of testosterone-mediated reproductive effort in a nonhuman primate, this project will shed light on the selective pressures and potential influence of energetics in shaping non-human primate and hominin species. Through the course of this research, the Co-PI will provide training in lab-based behavioral endocrinology techniques for undergraduate students from groups underrepresented in STEM fields. In addition, the Co-PI will conduct science education and conservation outreach at various domestic and international venues.This project will study wild gelada monkeys as a model to examine the relationship between male energetic condition, physiology, and male quality as assessed from vocal and visual signals used in male-male competition. Towards this end, this project will combine classic behavioral observations with innovative methods in (1) digital photogrammetry to assess male chest patch coloration, and (2) endocrinology to determine energetic condition from non-invasively collected urine and fecal samples. The polygynous mating system of gelada monkeys provides an ideal model to investigate contrasts in male reproductive energetics: harem-holding gelada leader males sire the vast majority of offspring while bachelor males in all-male groups lack reproductive opportunities. Reproductive success is therefore heavily skewed towards gelada leader males, and bachelors must overthrow a leader during energetically challenging "takeover" events to gain reproductive access to females. This research will evaluate the underlying seasonal variation in male energetic condition, how this variation relates to male social status, and whether energetic condition ultimately constrains testosterone-dependent signaling and male reproductive strategies. Although ample evidence suggests that lower food availability and energy may constrain male reproductive physiology, a comprehensive picture of the interrelationship between testosterone, energy, and reproduction in male primates is needed. This research will be one of the first to assess how energy may be a limiting factor for male reproductive success in wild primates.