Abstract
The evolution of dispersal is investigated in a landscape of manypatches with fluctuating carrying capacities and spatialheterogeneity in temporal fluctuations. Although asynchronoustemporal fluctuations select for dispersal, spatial heterogeneityin the distribution of fluctuating environmental variables selectsagainst it. We find evolutionary branching in dispersal rateleading to the evolutionarily stable coexistence of a high- and alow-dispersal phenotype. We study how the opposing forces ofselection for and against dispersal change with the relative sizeand the environmental qualities of the source and sink habitats.Our results suggest that the evolution of dispersal dimorphismcould be a first step towards speciation and local adaptation.