Department of Ecology and Evolutionary Biology, University of where p is the fraction of habitats occupied by the species California, Irvine, California 92697-2525 in question, m is the colonization rate of empty patches, and e is the extinction rate of occupied patches. The Submitted November 4, 1997; Accepted February 17, 1998 nontrivial equilibrium p* 5 1 2 (e/m) is globally stable as long as m . e. The Levins model is directly analogous to the logistic model dN/dt 5 rN[1 2 (N/K)] (Gilpin and Hanski