Social rank and darwinian fitness in a multimale group of Barbary macaques (Macaca sylvana Linnaeus, 1758). Dominance reversals and male reproductive success.

In a 5-year study data were compared on rank and reproductive success of 3 mature males in a group of barbary macaques who had sired 32 infants on 14 females. The results indicate that the absolute number of offspring as well as the proportion of offspring from higher-ranking females is a function of the male's rank. Asymmetrical access to receptive females was produced by either a high basic rank or by the formation of a coalition, or both of these, which resulted in at least partial exclusion of competitors from reproduction. Rank reversals in basic rank was preceded by severe fights between the opponents involving deep wounds or loss of canine teeth. When such fights occurred they reaped benefits in each case for the challenger, which were measurable in terms of reproductive success.