Kinship and intragroup social dynamics in two sympatric African Colobus species

Kinship has been described as a major factor shaping primates’ social dynamics, with individuals biasing their affiliative interactions to their related counterparts. However, it has also been demonstrated that, under certain circumstances, social bonding can be established in the absence of kin. The fact that Colobus polykomos (western black-and-white colobus) and Procolobus badius temminckii (Temminck’s red colobus) often live in sympatry (subject to the same ecological/anthropogenic pressures) but exhibit contrasting social systems makes them good models to test which factors shape their social systems. We investigated the influence of kinship on intragroup social dynamics of one focal group of each species present in Cantanhez National Park, Guinea-Bissau. Between October 2008 and June 2009 we used focal sampling to collect information on the individuals’ nearest neighbors and ad libitum sampling to collect data on intragroup social interactions. We estimated pairwise relatedness using fecal DNA from 9 individuals of Colobus polykomos and 15 individuals of Procolobus badius temminckii genotyped at 15 microsatellite loci. We found that, in the focal group of Colobus polykomos, individuals showed no preference to interact or be spatially closer to related partners. Moreover, mainly unrelated females and related males composed the focal group of Procolobus badius temminckii but grooming was most frequent among female dyads and only rarely involved male dyads. We conclude that kinship is not an important factor determining the social bonding in either study species, suggesting that other factors, e.g., anthropogenic, ecological, may be at play shaping these groups’ social bonding.