The evolution of social philopatry and dispersal in female mammals

In most social mammals, some females disperse from their natal group while others remain and breed there throughout their lives but, in a few, females typically disperse after adolescence and few individuals remain and breed in their natal group. These contrasts in philopatry and dispersal have an important consequence on the kinship structure of groups which, in turn, affects forms of social relationships between females. As yet, there is still widespread disagreement over the reasons for the evolution of habitual female dispersal, partly as a result of contrasting definitions of dispersal. This paper reviews variation in the frequency with which females leave their natal group or range (social dispersal) and argues that both the avoidance of local competition for resources and breeding opportunities and the need to find unrelated partners play an important role in contrasts between and within species.