title: Evaluation of genetic isolation within an island flora reveals unusually widespread local adaptation and supports sympatric speciation.
abstract: It is now recognized that speciation can proceed even when divergent natural selection is opposed by gene flow. Understanding the extent to which environmental gradients and geographical distance can limit gene flow within species can shed light on the relative roles of selection and dispersal limitation during the early stages of population divergence and speciation. On the remote Lord Howe Island (Australia), ecological speciation with gene flow is thought to have taken place in several plant genera. The aim of this study was to establish the contributions of isolation by environment (IBE) and isolation by community (IBC) to the genetic structure of 19 plant species, from a number of distantly related families, which have been subjected to similar environmental pressures over comparable time scales. We applied an individual-based, multivariate, model averaging approach to quantify IBE and IBC, while controlling for isolation by distance (IBD). Our analyses demonstrated that all species experienced some degree of ecologically driven isolation, whereas only 12 of 19 species were subjected to IBD. The prevalence of IBE within these plant species indicates that divergent selection in plants frequently produces local adaptation and supports hypotheses that ecological divergence can drive speciation in sympatry.
authors: Grand Challenges in Ecosystem and the Environment Initiative, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK alexander.papadopulos@plants.ox.ac.uk.
authors: Alexander S T
authors: AS
authors: Papadopulos
authors: School of Biological Sciences, University of Aberdeen, Aberdeen AB24 3FX, UK.
authors: Maria
authors: M
authors: Kaye
authors: Institut des Sciences de l'Evolution de Montpellier, UMR 5554, 34095 Montpellier, France.
authors: Céline
authors: C
authors: Devaux
authors: Grand Challenges in Ecosystem and the Environment Initiative, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK.
authors: Helen
authors: H
authors: Hipperson
authors: Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada B3H 4R2.
authors: Jackie
authors: J
authors: Lighten
authors: Grand Challenges in Ecosystem and the Environment Initiative, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK.
authors: Luke T
authors: LT
authors: Dunning
authors: Lord Howe Island Museum, Lord Howe Island, PO Box 157, New South Wales 2898, Australia.
authors: Ian
authors: I
authors: Hutton
authors: Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK.
authors: William J
authors: WJ
authors: Baker
authors: Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
authors: Roger K
authors: RK
authors: Butlin
authors: Grand Challenges in Ecosystem and the Environment Initiative, Imperial College London, Silwood Park Campus, Ascot, Berkshire SL5 7PY, UK Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3DS, UK v.savolainen@imperial.ac.uk.
authors: Vincent
authors: V
authors: Savolainen
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D001315:Australia; D003198:Computer Simulation; D051456:Gene Flow / Q000235:genetics; D049810:Genetic Speciation; D005828:Genetics, Population; D005838:Genotype; D005843:Geography; D062312:Islands; D008957:Models, Genetic; D063148:Plant Dispersal / Q000235:genetics*; D010944:Plants / Q000235:genetics*; D060047:Reproductive Isolation; D013045:Species Specificity
keywords: ecological speciation; genetic structure; local adaptation