Grooming networks reveal intra- and intersexual social relationships in Macaca thibetana.

Abstract

The analysis of grooming networks is a powerful tool to examine individual social and sexual relationships and how these relationships change over time. In this study, we investigated the seasonal dynamics of intra- and intersexual social relationships in Tibetan macaques (Macaca thibetana) based on grooming interactions. Similar to other female philopatric and male dispersal primates, female Tibetan macaques form the core of the social group with higher values of centralities, compared to the males who tend to be distributed on the periphery of the grooming network. The results of this study indicate that females formed stable clusters with maternal kin-related female partners both during the mating and non-mating season. Males were not included in the females' clusters during the mating season, however, during the non-mating season high-ranking males joined females to form loosely connected clusters. Male-female clustering was associated with the frequency of grooming (bouts per hour) rather than grooming duration (bout length). Our results illustrate that Tibetan macaque social networks fluctuate in response to reproductive seasonality and appear to play a role in mating choice and male reproductive success. Moreover, our results indicate that the frequency of grooming interactions might be more effective than the duration of grooming interactions in establishing cluster pattern on group level. It appears that changes in male mating strategies may drive these shifting social relationships and networks. Future studies on Tibetan macaques will need to investigate the degree to which changes in male grooming strategies directly correlate with male reproductive success.