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.
