Mean time to extinction of a metapopulation with an Allee effect

The incorporation of Allee effects into a simple metapopulation extinction model reveals a large non-linear reduction in mean time to extinction with small changes in an Allee limit. The extent of this reduction is dependent on the level of migration in the metapopulation. With small amounts of migration, small changes in the Allee limit result in large changes in the mean time to extinction. With higher levels of migration, the mean time to extinction is not as sensitive to changes in the Allee limit, becoming more similar to the single population case. The metapopulation modeled here is a set of nine patches, driven to extinction by environmental stochasticity. A generalized Allee effect is incorporated by a modification of the standard logistic model. The sensitivity of the mean time to extinction to small changes in the Allee limit is especially relevant to population viability analysis, which uses estimates of extinction times for management decisions. (C) 2001 Elsevier Science B.V. All rights reserved.