Does social complexity lead to sex-biased dispersal in polygynous mammals? A test on ground-dwelling sciurids

Mating systems are well known to influence the dispersing sex, but the magnitude of the sex-biased dispersal has not actually been measured, whereas many theoretical predictions have been made. In this study, we tested a new prediction about the coevolution between natal dispersal and sociality from a recent evolutionarily stable strategy (ESS) approach. From a comparative approach, we showed that, in agreement with the model, the male-biased dispersal increases with increasing level of sociality in polygynous ground-dwelling sciurids. In addition, the increase in male-biased dispersal with increasing sociality results from an increase in male dispersal rates, whereas female dispersal rates remain constant, contrary to what is expected from the ESS model. Although the mating system through the level of polygyny could act as a confounding factor, our results strengthen previous work that states that inbreeding avoidance plays a major role in the evolution of dispersal for the most social mammalian species. Copyright 2004.