A species-based theory of insular zoogeography

1 I present an alternative to the equilibrium theory of island biogeography, one which is based on the premise that many of the more general patterns in insular community structure result from, not despite, nonrandom variation among species. 2 For the sake of simplicity, the model is limited to patterns and processes operating over scales of ecological space and time: evolution is not included in the current version of the model. 3 The model assumes, as did MacArthur and Wilson's model, that insular community structure is dynamic in ecological time, but the model does not assume a balance, or equilibrium, of immigration and extinction. 4 The model presented here is hierarchical, phenomenological (it requires little parameterization beyond that which is directly derived from distributional data), graphical, and it includes potential feedback processes (including interspecific interactions). 5 The model offers an alternative explanation for a variety of patterns ranging from distributions of individual species, species-area and species-isolation relationships, to patterns of assembly of insular communities. The model also generates some new predictions and identifies some potentially important areas for future studies.