This research will investigate female competition over mates in a wild population of Sanje mangabeys (Cercocebus sanjei), in the Udzungwa Mountains of Tanzania. This study will address two major questions. First, are some females better able than others to enact their reproductive goals, i.e. mating with preferred males at times of conception while preventing other females from doing so? Second, if so, by what methods is this achieved? To answer these questions, behavioral observations on sexual and social behavior will be combined with data on ovarian hormones gathered through analysis of fecal samples. This unique double-sided approach of behavioral and endocrinological data will provide the information necessary to identify differences in female, as well as male, behavior in response to changes in female reproductive state.
Established theory views females as less sexually competitive than males. As a result, most studies of sexual competition focus on male behavior. It is females, however, that invest most heavily in reproduction (e.g., gestation and lactation), with males generally contributing only sperm, providing little or no offspring care. Consequently, for females to be reproductively successful, i.e., have offspring survive to maturity; they must expend significant energy to care for offspring or receive supplemental support, e.g., access to food, from other group members, such as adult males. To ensure such support is provided, females may have to compete over access to preferred mates. It is expected that a female will prefer and compete over the male(s) that provide the greatest benefits to her and her offspring, while at the same time mating promiscuously to confuse paternity, which has been shown to encourage aid and discourage infanticide from other males. It remains unclear, however, to what degree females compete over access to mates, and what impact this has on female reproduction.
The intellectual merits of this project include providing a better understanding of the factors regulating female-female and male-female social relationships, and contributing to a more refined understanding of the variables underlying sociality. The broader impacts of this study include aiding in the conservation of the endangered Sanje mangabey by providing (a) data on reproductive rates, essential to the development of appropriate management plans; (b) long-term continued research presence, an important deterrent to poaching and illegal activities; and (c) employment and training for Tanzanian field assistants. This study will also contribute to the training of a graduate student as part of his doctoral dissertation research.
