Evidence for a genetic basis for delayed dispersal in a cooperatively breeding canid

Among cooperatively breeding species, delayed dispersal provides an opportunity for older siblings to help rear young. There is considerable variation in the extent to which cooperative breeders delay dispersal, however, and while delayed dispersal may be a consequence of adaptive evolution favouring family living, evidence for a genetic basis is lacking. Furthermore, the extent to which dispersal behaviour itself is under direct selection, or evolves indirectly in response to selection on correlated life-history traits, remains unclear. We tested for evidence of inter- and intraspecific quantitative genetic variation in age at first dispersal in a reintroduced population of the red wolf, Canis rufus, that naturally hybridizes with the coyote, Canis latrans, which delays dispersal to a lesser extent than the red wolf. Using analyses based on individual relationships to population founders and sire–offspring regressions, we found evidence for intraspecific genetic variation in dispersal age in male, but not female, red wolves. We also found evidence for interspecific genetic variation, in that red wolves had later dispersal age than coyote–red wolf hybrids. Intraspecific variation in dispersal age was not explained by variation in social and environmental factors nor alternative targets of selection such as body mass or age at first reproduction. Thus, selection may act directly on dispersal-related behaviours. However, life-history traits may continue to be influential in creating interspecific differences in dispersal age, as hybrids also showed earlier reproduction. Our findings suggest that evolution of delayed dispersal may be due to both direct and indirect selection on existing quantitative genetic variation, and that genetic and environmental mechanisms underlying dispersal may differ between the sexes.