Maintaining genetic diversity despite local extinctions: effects of population scale

A large body of research emphasizes the importance of population subdivision and local extinction for lowering effective population size. However, the effects of spatial structure on effective population size depend strongly on the scale of correlation between individuals, and may even be independent of the apparent scale of population subdivision. Here, generalized simulation models are used to explore the relationship between effective population size and the scale of correlated deaths or local extinctions. If the probability of local extinction scales logarithmically with population size, then highly subdivided populations suffering Frequent local extinction may retain more diversity than less subdivided populations of equivalent size. This result clarifies the need for information on the scale of environmental correlation between individuals when applying genetic inference or genetic management strategies to natural populations. (C) 2001 Elsevier Science Ltd. All rights reserved.