How should we define fitness in structured metapopulation models? Including an application to the calculation of evolutionary stable dispersal strategies

摘要

We define a fitness concept applicable to structured metapopulations consisting of infinitely many equally coupled patches. In addition, we introduce a more easily calculated quantity R_m that relates to fitness in the same manner as R_0 relates to fitness in ordinary population dynamics: the R_m of a mutant is only defined when the resident population dynamics converges to a point equilibrium and R_m is larger (smaller) than 1 if and only if mutant fitness is positive (negative). R_m corresponds to the average number of newborn dispersers resulting from the (on average less than one) local colony founded by a newborn disperser. Efficient algorithms for calculating its numerical value are provided. As an example of the usefulness of these concepts we calculate the evolutionarily stable conditional dispersal strategy for individuals that can account for the local population density in their dispersal decisions. Below a threshold density c, at which staying and leaving are equality profitable, everybody should stay and above c everybody should leave, where profitability is measured as the mean number of dispersers produced through lines of descent consisting of only nondispersers.