Pii: S0025-5564(00)00016-x

The evolution of dispersal is examined by looking at evolutionarily stable strategies (ESS) for dispersal parameters in discrete time multisite models without any cost of dispersal. ESS are investigated analytically, based on explicit results on sensitivity analysis of matrix models. The basic model considers an arbitrary number of sites and a single age class. An ESS for dispersal parameters is obtained when the spatial reproductive values, calculated at the density-dependent population equilibrium, are equal across sites. From this basic formulation, one derives equivalently that all local populations should be at equilibrium in the absence of migration, and that dispersal between sites should be balanced, i.e., the numbers of individuals arriving to and leaving a site are equal. These results are then generalized to a model with several age classes. Equal age-speci®c reproductive values do not however imply balanced dispersal in this case. Our results generalize to any number of sites and age classes those available [M. Doebeli, Dispersal and dynamics, Theoret. Popul. Biol. 47 (1995) 82] for two sites and one age class. Ó 2000 Elsevier Science Inc. All rights reserved.