title: Ecological speciation in sympatric palms: 1. Gene expression, selection and pleiotropy.
abstract: Ecological speciation requires divergent selection, reproductive isolation and a genetic mechanism to link the two. We examined the role of gene expression and coding sequence evolution in this process using two species of Howea palms that have diverged sympatrically on Lord Howe Island, Australia. These palms are associated with distinct soil types and have displaced flowering times, representing an ideal candidate for ecological speciation. We generated large amounts of RNA-Seq data from multiple individuals and tissue types collected on the island from each of the two species. We found that differentially expressed loci as well as those with divergent coding sequences between Howea species were associated with known ecological and phenotypic differences, including response to salinity, drought, pH and flowering time. From these loci, we identified potential 'ecological speciation genes' and further validate their effect on flowering time by knocking out orthologous loci in a model plant species. Finally, we put forward six plausible ecological speciation loci, providing support for the hypothesis that pleiotropy could help to overcome the antagonism between selection and recombination during speciation with gene flow.
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.
authors.forename: L T
authors.initials: LT
authors.lastname: Dunning
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.
authors.forename: H
authors.initials: H
authors.lastname: Hipperson
authors.affiliation: Royal Botanic Gardens, Kew, Richmond, UK.
authors.forename: W J
authors.initials: WJ
authors.lastname: Baker
authors.affiliation: Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK.|Sven Lovén Centre for Marine Sciences, Tjärnö, University of Gothenburg, Stromstäd, Sweden.
authors.forename: R K
authors.initials: RK
authors.lastname: Butlin
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.
authors.forename: C
authors.initials: C
authors.lastname: Devaux
authors.affiliation: Lord Howe Island Museum, Lord Howe Island, NSW, Australia.
authors.forename: I
authors.initials: I
authors.lastname: Hutton
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.
authors.forename: J
authors.initials: J
authors.lastname: Igea
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.|Royal Botanic Gardens, Kew, Richmond, UK.
authors.forename: A S T
authors.identifier: 0000-0001-6589-754X
authors.initials: AS
authors.lastname: Papadopulos
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.
authors.forename: X
authors.initials: X
authors.lastname: Quan
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Smadja
authors.affiliation: Department of Life Sciences, Imperial College London, London, UK.
authors.forename: C G N
authors.initials: CG
authors.lastname: Turnbull
authors.affiliation: Department of Life Sciences, Imperial College London, Ascot, UK.|Royal Botanic Gardens, Kew, Richmond, UK.
authors.forename: V
authors.initials: V
authors.lastname: Savolainen
mesh_terms: D028023:Arecaceae / Q000235:genetics*; D001315:Australia; D051456:Gene Flow; D049810:Genetic Speciation; D062312:Islands; D061350:Sympatry
keywords: Lord Howe Island; positive selection; sympatric speciation; transcriptomics