title: Molecular Evolutionary Consequences of Island Colonization.
abstract: Island endemics are expected to have low effective population sizes (Ne), first because some may experience population bottlenecks when they are founded, and second because they have restricted ranges. Therefore, we expect island species to have reduced genetic diversity, inefficient selection, and reduced adaptive potential compared with their mainland counterparts. We used both polymorphism and substitution data to address these predictions, improving on the approach of recent studies that only used substitution data. This allowed us to directly test the assumption that island species have small values of Ne We found that island species had significantly less genetic diversity than mainland species; however, this pattern could be attributed to a subset of island species that appeared to have undergone a recent population bottleneck. When these species were excluded from the analysis, island and mainland species had similar levels of genetic diversity, despite island species occupying considerably smaller areas than their mainland counterparts. We also found no overall difference between island and mainland species in terms of the effectiveness of selection or the mutation rate. Our evidence suggests that island colonization has no lasting impact on molecular evolution. This surprising result highlights gaps in our knowledge of the relationship between census and effective population size.
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, United Kingdom.
authors.forename: Jennifer E
authors.initials: JE
authors.lastname: James
authors.affiliation: Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia Division of Evolution Ecology and Genetics, Research School of Biology, the Australian National University, Canberra, Australian Capital Territory, Australia.
authors.forename: Robert
authors.initials: R
authors.lastname: Lanfear
authors.affiliation: School of Life Sciences, University of Sussex, Brighton, United Kingdom a.c.eyre-walker@sussex.ac.uk.
authors.forename: Adam
authors.initials: A
authors.lastname: Eyre-Walker
mesh_terms: D000818:Animals; D019143:Evolution, Molecular; D014644:Genetic Variation; D005828:Genetics, Population / Q000379:methods* / Q000706:statistics & numerical data; D058865:Introduced Species; D062312:Islands; D010802:Phylogeny; D011156:Population Density
keywords: bottlenecks; effective population size; genetic diversity; polymorphism; substitution