ON THE EVOLUTION OF DENSITY-DEPENDENT DISPERSAL IN A SPATIALLY STRUCTURED POPULATION-MODEL

A simple metapopulation lattice model of two competing phenotypes is p resented, where one phenotype reacts more sensitively to overcrowding by migrating to neighboring local habitats. The sensitivity is formula ted by means of a threshold density of the subpopulations, above which dispersal is triggered off. If this threshold density is not very far from the local carrying capacity, an increased mobility provides bene fits on the metapopulation level. At a surprisingly small difference b etween migrational triggering thresholds, the phenotype of larger mobi lity (or lower threshold) squeezes out the less mobile one from the wh ole system in a wide parameter range. Evolutionary considerations give an optimal threshold level for our model metapopulation. (C) 1997 Aca demic Press Limited.