Effects of metapopulation processes on measures of genetic diversity

Many species persist as a metapopulation under a balance between the local extinction of subpopulations or demes and their recolonization through dispersal from occupied patches. Here we review the growing body of literature dealing with the genetic consequences of such population turnover. We focus our attention principally on theoretical studies of a classical metapopulation with a `¢nite-island ’ model of population structure, rather than on c̀ontinent-island ’ models or `source^sink ’ models. In particular, we concern ourselves with the subset of geographically subdivided population models in which it is assumed that all demes are liable to extinction from time to time and that all demes receive immigrants. Early studies of the genetic e¡ects of population turnover focused on population di¡erentiation, such as measured by FST. A key advantage of FST over absolute measures of diversity is its relative independence of the mutation process, so that di¡erent genes in the same species may be compared. Another advantage is that FST will usually equilibrate more quickly following perturbations than will absolute levels of diversity. However, because FST is a ratio of between-population di¡erentiation to total diversity, the genetic e¡ects of metapopulation processes may be di¤cult to interpret in terms of FSTon its own, so that the analysis of absolute measures of diversity in addition is likely to be informative. While population turnover may either increase or decrease FST, depending on the mode of colonization, recurren