Parasite infection drives the evolution of state-dependent dispersal of the host.

Dispersal plays a fundamental role in shaping the ecological processes such as host-parasite interactions, and the understanding of host dispersal tendency leads to that of parasites. Here, we present the result of our study on how the evolutionarily stable dispersal of a host would depend on parasite infection, considering kin competition among neighbours. We show that the evolving dispersal rate might be higher for susceptible than for infected individuals (S-biased dispersal) or vice versa (I-biased dispersal). S-biased dispersal is favoured by strong virulence affecting competitive ability, by high rate of parasite release during dispersal, and by low virulence for infected emigrants (i.e. low virulence affecting dispersal ability), whereas I-biased dispersal is favoured in the opposite situation. We also discuss population structure or between-deme genetic differentiation of the host measured with Wright's FST. In I-biased dispersal, between-deme genetic differentiation decreases with the infection rate, while in S-biased dispersal, genetic differentiation increases with infection rate.