What traits promote male parallel dispersal in primates?

Abstract

Summary Parallel dispersal occurs when individuals emigrate together with peers or close kin, or immigrate into groups containing familiar or closely related individuals. To understand the evolution of parallel dispersal in male primates, we explore if parallel dispersal co-occurs with male coalitions, or with other traits that may facilitate coalition formation. We conducted a meta-analysis using phylogenetic comparative methods to test for an association between male parallel dispersal and male coalition formation, multi-male social groups, male-biased dispersal, high paternity concentration, and breeding seasonality. These traits were predicted to be correlated with parallel dispersal because they increase the availability of potential dispersal partners, increase individual competitive ability, or provide inclusive fitness benefits for cooperating relatives. Pairwise comparisons revealed that coalitions in general were significantly associated with male parallel dispersal. However, neither intergroup nor intragroup coalitions were associated with parallel dispersal when examined separately, though there was a trend towards significance for intergroup coalitions. Male-biased dispersal was equivocally associated with parallel dispersal, while multi-male social groups, paternity concentration, and breeding seasonality were not. These results suggest that the evolution of male parallel dispersal may be linked with the propensity of males to form coalitions and the need to retain coalition partners.