| Abstract: | The classical theory of island biogeography has as its basic variable the presence or absence of species on entire islands, and as its basic processes colonization and extinction rates on entire islands as functions of island area, distance, and so forth. Yet for many organisms with limited dispersal abilities, it may be more reasonable to consider larger islands as comprised of an ensemble of local populations coupled by within-island dispersal. Conceptual arguments and a simple patch occupancy model are used to examine the potential relevance of such internal spatial dynamics in explaining area effects, expressed via the probability that a species is present per unit area as a function of total island area. The model suggests that strong area effects depend on a rather fine balance between local colonization and extinction rates. A fruitful direction of future research should be the application of patch dynamic theory to classic island biogeographic questions and systems. |
