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

在哺乳动物中，雌性通常比雄性在每次繁殖过程中投入更多——这种不平衡往往导致雄性和雌性的繁殖策略不同。典型的男性策略是与尽可能多的女性交配，而女性通常更“挑剔”，只会在有利的社会和环境条件下交配。雄性繁殖策略最突出的例子可能是杀婴——雄性杀死雌性未断奶的后代（由另一个雄性所生），以加速雌性回到可育状态。反过来，为了保护自己的繁殖能力，雌性哺乳动物通常会发展出对抗杀婴行为的策略，比如与社会群体中的其他个体结成防御联盟，制造欺骗性的性行为和性肿胀来模仿生育的迹象，自发流产怀孕，或过早断奶依赖的幼崽。关于野生狒狒（Theropithecus gelada）的轶事证据表明，雄性狒狒接管后的杀婴行为可能对具有依赖后代的雌性狒狒构成威胁。然而，到目前为止，雌性狒狒的生殖对抗策略从未被研究过。本项目旨在研究雌性狒狒生殖策略的功能和潜在生理学，以回答这个问题：狒狒是否存在两性冲突？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狒狒生殖的规范模式。第二个目标是研究雄性狒狒接管雌性狒狒后的生理、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行为是否对雌性狒狒构成威胁，以及雌性狒狒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，它从机制和适应性两方面探讨了狒狒中存在的两性冲突的可能性。女性的生理特征将揭示女性是否将男性的接管视为威胁，以及女性的性膨胀是否具有欺骗性。实地观察将为解释激素数据提供行为背景。荷尔蒙和行为结合在一起，可以更全面地了解正在发生的事情。这是首次研究灵长类动物雌性生殖策略的激素和行为。其次，将从女性的角度来研究杀婴行为。虽然杀婴行为已经在各种物种中进行了调查，但研究主要集中在雄性的成本和收益上。对灵长类动物雌性生殖策略和反策略的进一步研究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。狒狒是一种濒危物种，提高对它们繁殖行为的了解有助于圈养环境下的繁殖工作。

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.