Natal dispersal patterns in a social wild mammal: What does family tell us?

Abstract

Natal dispersal is a key process in ecology and evolution. Similarities of dispersal patterns between relatives can lead to small-scale kin structure within populations with consequences for population dynamics and genetics. Most studies have focused on birds, lizards, and small mammals. How family effects may shape sex-specific natal dispersal patterns in a large-sized social mammal remains unexplored. We fill this gap thanks to a 30-year-long monitoring of a wild boar population. This polytocous, polygynous, and size dimorphic species displays a matrilineal social organization. From the monitoring of individuals from early life to adulthood, we characterized natal dispersal patterns by investigating the propensity to disperse and the dispersal distance. As expected for a species subjected to strong sexual selection, offspring males dispersed more often and farther than females. Looking specifically at similarities of dispersal patterns among relatives within a group, we found that offspring females from the same family displayed more similar dispersal propensity and distance than females from different groups, highlighting family effects. However, this dispersal pattern did not hold for males. Family effects can thus shape natal dispersal patterns in a sex-specific way in social mammals and are key to understanding individual variation in dispersal patterns.