The evolution of sexual difference in dispersal strategy sensitive to population density

Abstract

Empirical studies reveal that dispersal behavior is dependent on local population density in different wild animals. Theoretical studies also pay much attention to modeling dispersal strategies sensitive to population density; however, the evolution of sex-biased dispersal has not been analyzed sufficiently by a model considering density-dependent dispersal. Therefore, a previous model where it is assumed that only genetic factors determine an individual's dispersal timing was thoroughly modified. The resultant model assumes that dispersal timing is determined by the interaction of genetic factors with local population density and local habitat size. This model demonstrates that when females copulate before dispersal, they evolve to emigrate from their natal habitat earlier than males. A model where dispersal timing is dependent on the local sex ratio instead of population density was also analyzed. This model also results in the evolution of female early dispersal, but the resultant dispersal timing of both sexes is slightly different from the model sensitive to population density. This difference is related to sexual difference in factors affecting reproductive success. Local population density is associated with the intensity of resource competition among females, whereas local sex ratio is informative for mate competition among males.