Direct fitness benefits of delayed dispersal in the cooperatively breeding red wolf (Canis rufus)

The existence of cooperative breeding in diverse animal taxa has inspired much interest in what nonbreeding helpers gain from participation in rearing nondescendent young. A major theoretical explanation for this phenomenon has revolved around the notion of inclusive fitness, where delayed dispersers in a family-based group gain indirect fitness benefits by fostering the viability of close relatives. There is potential, however, for direct fitness benefits in delayed dispersal itself. We explored the relationship between delayed dispersal and lifetime fitness in a reintroduced population of the cooperatively breeding red wolf, Canis rufus, which exhibits delayed dispersal but few opportunities to breed in the natal pack. We present evidence that male wolves that delayed dispersal to later ages had lower mortality risk from natural and anthropogenic sources combined and increased probability of becoming reproductive in their lifetimes. Furthermore, delayed dispersal did not result in delayed age at first reproduction. For females, however, the relative costs and benefits of delaying dispersal to later ages were more complex. In general, we provide evidence that there are direct fitness benefits to delaying dispersal in red wolves even in the absence of reproductive opportunities in the natal pack. Thus, we lend support to the hypothesis that direct fitness benefits may in themselves be sufficient to facilitate the evolution of delayed dispersal requisite to cooperatively breeding social systems. Copyright 2011, Oxford University Press.