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DOI

  • Dmitry A Filatov
    Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
  • Owen G Osborne
    Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.
  • Alexander S T Papadopulos
    Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, UK.Department of Conservation Science, Royal Botanic Gardens, Kew, Richmond TW9 3AB, UK.

Hybrid zones typically form as a result of species coming into secondary contact, but can also be established in situ as an ecotonal hybrid zone, a situation which has been reported far less frequently. An altitudinal hybrid zone on Mount Etna between two ragwort species (the low elevation Senecio chrysanthemifolius and high elevation S. aethnensis) could potentially represent either of these possibilities. However, a scenario of secondary contact vs. speciation with gene flow has not been explicitly tested. Here, we test these alternatives and demonstrate that the data do not support secondary contact. Furthermore, we report that the previous analyses of speciation history of these species were based on admixed populations, which has led to inflated estimates of ongoing, interspecific gene flow. Our new analyses, based on 'pure' S. aethnensis and S. chrysanthemifolius populations, reveal gene exchange of less than one effective migrant per generation, a level low enough to allow the species to accumulate neutral, genomewide differences. Overall, our results are consistent with a scenario of speciation with gene flow and a divergence time which coincides with the rise of Mt. Etna to altitudes above 2000 m (~150 KY). Further work to quantify the role of adaptation to contrasting environments of high and low altitudes will be needed to support the scenario of recent ecological speciation in this system.

Keywords

  • Adaptation, Physiological, Altitude, DNA, Plant, Gene Flow, Genetic Speciation, Genetics, Population, Hybridization, Genetic, Models, Genetic, Phenotype, Polymorphism, Single Nucleotide, Senecio, Sequence Analysis, DNA, Sicily, Journal Article
Original languageEnglish
Pages (from-to)2467-81
Number of pages15
JournalMolecular Ecology
Volume25
Issue number11
Early online date20 Apr 2016
DOIs
Publication statusPublished - Jun 2016
Externally publishedYes
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