Ecological Shifts and the Evolution of Geographically Restricted Species of North American Peromyscus (Mice)

A major trend in the historical biogeography of Peromyscus appears to have been the generation of species of limited distribution from more widespread species. Accompanying these range restrictions are a number of ecological shifts, including penetration of stable species-rich communities from marginal species-poor ones, reduction in habitat versatility, and a decrease in reproductive potential. These continental patterns are compared to similar island patterns in terms of the taxon cycle. The importance of adaptive trade-offs between colonizing ability and local adaptation in generating taxon cycles is emphasized. Finally, studies of the ecology of colonization and the evolution of restricted species are viewed as a promising means for fashioning a general theory of the 'biogeography of the species' which is applicable on continents, as well as on islands.