The effect of female polyandry and sperm precedence on the evolution of sexual difference in dispersal timing

Predispersal copulation and unpredictable environment facilitate the evolution of female-biased dispersal in species, where females are functionally monandrous. Females should migrate and reproduce over different habitats to spread their risks due to environmental fluctuation. On the other hand, males do not have to disperse because their risks are spread by their mating partners who produce their offspring in different habitats. However, when females are functionally polyandrous, it is expected that they will not contribute to spreading the male's risk extensively. Therefore, by simulation with the individual based model, the present study evaluated how female polyandry influences the sexual difference in dispersal timing. This model revealed that when females are polyandrous, the timing of female remating and sperm priority patterns have an important influence on the evolution of sex-biased dispersal. Particularly when female remating is not synchronized with dispersal or when last-male sperm precedence does not exist, female-biased dispersal is evolved.