Doctoral Dissertation Improvement: Behavioral Endocrinology and Reproductive Strategies of Wild Female Geladas

在哺乳动物中，雌性在每个生殖事件上的投资通常比雄性更多--这种不平衡往往导致雄性和雌性的不同生殖策略。典型的雄性策略是与尽可能多的雌性交配，而雌性通常更“挑剔”，只有在有利的社会和环境条件下才会交配。男性生殖策略最突出的例子可能是杀婴--即一只雄性杀死雌性未断奶的后代(由另一只雄性繁殖)，以加速其恢复到可生育状态。反过来，为了保护自己的繁殖努力，雌性哺乳动物通常会制定出对抗杀婴的策略，比如与其社会群体中的其他个体结成防御性联盟，产生欺骗性行为和性膨胀来模仿生育迹象，自发流产，或者提前断奶依赖的幼崽。关于野生美洲狮(Theropithecus Glada)的轶事证据表明，雄性接管后的杀婴行为可能会对依赖后代的雌性构成威胁。然而，到目前为止，从未研究过鬣羚的雌性生殖对策。本项目旨在研究花斑羚雌性生殖策略的功能和潜在的生理机制，以回答这样一个问题：在花斑羚中是否存在两性冲突？第一个目标是从性腺激素、性肿胀和雌性生殖行为方面描述狐狸繁殖的标准模式。第二个目标是调查雄性接管后雌性美洲狮的生理、性肿胀和生殖行为背后的功能意义。换句话说，这项研究将确定杀婴是否对雌性鬣羚构成威胁，以及雌性是否因此制定了应对策略。这项研究在两个方面是独一无二的。首先，它从机械性和适应性两个方面探讨了雌雄之间存在冲突的可能性。女性的生理档案将揭示女性是否将男性的接管视为一种威胁，以及女性的性膨胀是否具有欺骗性。现场观察将提供解释荷尔蒙数据的行为背景。荷尔蒙和行为结合在一起，就能更全面地了解正在发生的事情。这是第一次研究灵长类动物中围绕雌性生殖策略的荷尔蒙和行为。其次，将从女性的角度调查杀婴行为。虽然在各种物种中对杀婴进行了调查，但研究主要集中在男性的成本和收益上。进一步记录灵长类物种的雌性生殖策略和反制策略将有助于更好地理解两性间的冲突。这项工作的数据将具有重要的保护意义。狐狸是一种濒临灭绝的物种，对它们生殖行为的了解有助于在圈养环境中进行繁殖。

Among mammals, females generally invest more than males in each reproductive event -- an imbalance that often results in different reproductive strategies for males and females. The typical male strategy is to mate with as many females as possible while females are generally more "choosy" and will only mate under favorable social and environmental conditions. Possibly the most salient example of a male reproductive strategy is infanticide - when a male kills a female's unweaned offspring (sired by another male) to hasten her return to a fertile state. In turn, to protect their reproductive effort, female mammals often develop counterstrategies to infanticide such as forming defensive alliances with other individuals in their social groups, producing deceptive sexual behavior and sexual swellings to mimic the signs of fertility, spontaneously aborting a pregnancy, or prematurely weaning dependent young. Anecdotal evidence on wild geladas (Theropithecus gelada), a close relative of baboons, suggests that infanticide following male takeovers may be a threat for females with dependent offspring. However, as yet, female reproductive counterstrategies in geladas have never been examined. This project aims to investigate the function and underlying physiology of female reproductive strategies in geladas, to answer the question: does intersexual conflict exist in geladas? The first objective is to describe the normative patterns of gelada reproduction in terms of gonadal hormones, sexual swellings, and female reproductive behavior. The second objective is to investigate the functional significance behind the physiology, sexual swellings, and reproductive behavior of female geladas following male takeovers. In other words, this research will determine whether infanticide is a threat to female geladas and whether females have developed counterstrategies as a result. This research is unique in two ways. First, it explores the potential for intersexual conflict to exist in geladas from both mechanistic and adaptive approaches. Female physiological profiles will reveal whether females perceive male takeovers as a threat and whether female sexual swellings are deceptive or not. Field observations will provide the behavioral context with which to interpret the hormonal data. Together, the hormones and behavior yield a more complete picture of what is going on. This is the first study to investigate the hormones and behavior surrounding female reproductive strategies in primates. Second, infanticide will be investigated from the female's perspective. While infanticide has been investigated in a variety of species, research has strongly focused on the costs and benefits for males. Further documentation of female reproductive strategies and counterstrategies in primate species will contribute towards a better understanding of intersexual conflict.Data from this work will have important conservation implications. Geladas are an endangered species and improved understanding of their reproductive behavior can help breeding efforts in captive settings.