How sympatric is speciation in the Howea palms of Lord Howe Island?

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  • Wiesław Babik
    Imperial College London Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK.
  • Roger K Butlin
  • William J Baker
  • Alexander S T Papadopulos
    Imperial College London, UK
  • Matthieu Boulesteix
  • Marie-Charlotte Anstett
  • Christian Lexer
  • Ian Hutton
  • Vincent Savolainen

The two species of the palm genus Howea (Arecaceae) from Lord Howe Island, a minute volcanic island in the Tasman Sea, are now regarded as one of the most compelling examples of sympatric speciation, although this view is still disputed by some authors. Population genetic and ecological data are necessary to provide a more coherent and comprehensive understanding of this emerging model system. Here, we analyse data on abundance, juvenile recruitment, pollination mode and genetic variation and structure in both species. We find that Howea forsteriana is less abundant than Howea belmoreana. The genetic data based on amplified fragment length polymorphisms markers indicate similar levels of variation in the two species, despite the estimated census population size of H. belmoreana being three times larger than that of H. forsteriana. Genetic structure within species is low although some weak isolation by distance is detectable. Gene flow between species appears to be extremely limited and restricted to early-generation hybrids - only three admixed individuals, classified as F2s or first generation backcrosses to a parental species, were found among sampled palms. We conclude that speciation in Howea was indeed sympatric, although under certain strict definitions it may be called parapatric.


  • Amplified Fragment Length Polymorphism Analysis, Arecaceae, Australia, DNA, Plant, Gene Flow, Genetic Speciation, Genetic Variation, Genetics, Population, Geography, Phylogeny, Pollination, Sequence Analysis, DNA, Species Specificity, Journal Article, Research Support, Non-U.S. Gov't
Original languageEnglish
Pages (from-to)3629-38
Number of pages10
JournalMolecular Ecology
Issue number17
Publication statusPublished - Sep 2009
Externally publishedYes
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