抄録
Male reproductive skew varies considerably between primate species and may depend on males' abilities to defend access to females (tug-of-war or limited control model), their relatedness to the adult females in the group (inbreeding avoidance model), or their reliance on coalitionary support from other males (reproductive concessions model). Using demographic and genetic data collected between 1993 and 2012, we investigated whether these models could predict male reproductive skew in four groups of white-faced capuchins (Cebus capucinus) in Sector Santa Rosa, Costa Rica. The majority of infants were sired by alpha males (85/106 infants). In contrast to the expectations of the limited control model, the siring success of alpha males was not influenced by the number of co-resident females, the number of co-resident males, or synchrony in the timing of conceptions. The alpha male only sired 1 of 13 infants born to his daughters, which supports the inbreeding avoidance model. Although alpha males were tolerant of subordinate males' mating attempts, subordinates rarely sired infants (21/106 infants). The high reproductive skew is surprising because alpha males rely on coalitionary support from subordinate males in order to repel rival males. It is possible that alpha males do not need to offer concessions or staying-incentives if subordinate males are unlikely to gain reproductive opportunities in other groups.
