Doctoral Dissertation Improvement: Reproductive Strategies of Male White-Faced Capuchins (Cebus capucinus) in the Santa Rosa Sector of the ACG, Costa Rica

Tulane University, New Orleans LA

Investigators

Abstract

The research objective of this study is to examine how and why dominant males sire the most offspring by collecting behavioral data on males, hormonal data on both sexes, and genetic data in three groups of C. capucinus in the Santa Rosa Sector of the Área de Conservación Guanacaste, Costa Rica. Sexual selection theory suggests that because fertile females are a limited resource, males should compete over access to them and therefore display only low levels of cooperation. White-faced capuchins (Cebus capucinus) live in groups of multiple related females and immigrant males. While the social system of C. capucinus is based on close bonds among group females, it also involves cooperative alliances among group males. Within-group male-male aggression and overt mating competition are rare, with all males participating in the mating system. The socioecological model predicts that when within-group competition is low and between group competition is high, males should have equal reproductive success. Yet, contrary to theoretical predictions and behavioral observations, dominant males sire the majority of offspring. Intellectual Merit: This study is one of few projects involving the simultaneous collection of hormonal data on males and females. In combination with behavioral and genetic data, these data will to contribute to on-going research on reproductive skew theory, to understand proximate causes of variation in male reproductive success, to test the applicability of the Challenge Hypothesis, and to increase the availability of comparative data which can provide insight into human evolution. Broader Impacts: This project will contribute to the database of long-term (25+ years) research on the capuchins of Santa Rosa, while also providing invaluable training for local and foreign assistants in the use of field techniques. This doctoral dissertation research project will contribute to the academic training of a female graduate student.