1Department of Integrated Biosciences, University of Tokyo, 2Department of Anthropology and Archaeology, University of Calgary, 3Department of Anthropology, Tulane University
March 26, 2015 11:00, Grand Ballroom E/F/G
Reproduction is skewed towards the alpha male in many primate populations, yet subordinate males often support the alpha during agonistic encounters with extra-group members. To improve our understanding of why subordinate males cooperate in populations with high reproductive skew, we investigated the siring success of dominant and subordinate male white-faced capuchins (Cebus capucinus) using 19 years of demographic and genetic data collected from 4 groups at Sector Santa Rosa, Costa Rica. Alpha males sired 91% of the infants born to unrelated females, and there was a trend for their reproductive success to increase with the number of subordinate males. Subordinate males were not more likely to remain in the group if they gained reproductive opportunities. Instead, the subordinate male's age relative to the alpha male had a positive effect on emigration, whereby males were more likely to emigrate as their age approached or exceeded that of the alpha male. If relatively young males are more likely to outlive the alpha, queuing for the alpha position is a more viable strategy for young than for old males. Some subordinate males gained reproductive opportunities when daughters of alpha males reached sexual maturity or when the former alpha male died or dispersed. These males sired a similar number of offspring as males that became alpha upon entry into a group. Alternative routes to reproductive success, which only become apparent when analyzing data over long time periods, may explain cooperation in populations with high reproductive skew.
Japan Society for Promotion of Science, NSERC, Canada Research Chairs, LSB Leakey Foundation, Tulane University’s Department of Anthropology, Stone Center for Latin American Studies, Newcomb Institute, and Research Enhancement Fund