The interaction of male and female reproductive strategies and paternity in wild Japanese macaques, Macaca fuscata

Abstract

Japanese macaques reside in large, mixed-sex social groups in which various reproductive strategies of both sexes operate simultaneously. This report represents the first study combining behavioural and genetic data to examine the interaction of male and female reproductive strategies in primates (N=15 adult males, N=15 adult females, Yakushima Island, Japan). During one mating season, socially dominant males monopolized most female matings. Furthermore, the six offspring sired by troop males were more likely sired by higher-ranking males than lower-ranking males. Nontroop males sired three additional offspring in the troop. Lower-ranking troop males avoided direct competition with higher-ranking males by engaging in sneak copulations with females outside of the presence of other males. Also, females expressed mate choice behaviour towards multiple males of various dominance ranks. Thus, the female strategy of attempting to mate with multiple males conflicted with the mate-guarding strategy of high-ranking males. Despite some female mate choice for mid- and low-ranking males and alternative male mating tactics by subordinate males, high-ranking males were able to monopolize most, but not all, within-troop mating and paternity. This result was due in part to the low number of females mating at the same time. The mean number of females displaying mating behaviour per day was 2.42 (range 1–5), and higher-ranking males more successfully monopolized females on days when fewer females were mating. The number of females mating simultaneously influences the outcome of reproductive conflicts between the sexes.