Hybrid origin of Audubon’s warbler

Authors

  • ALAN BRELSFORD,

    1. Department of Zoology, and Biodiversity Research Centre, University of British Columbia. 6270 University Blvd., Vancouver BC, Canada V6T 1Z4
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    • Present address: Department of Ecology and Evolution, University of Lausanne, Quartier Sorge, Bâtiment Biophore, 1015 Lausanne, Switzerland.

  • BORJA MILÁ,

    1. National Museum of Natural Sciences, Spanish Research Council (CSIC), José Gutiérrez Abascal 2, Madrid 28006, Spain
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  • DARREN E. IRWIN

    1. Department of Zoology, and Biodiversity Research Centre, University of British Columbia. 6270 University Blvd., Vancouver BC, Canada V6T 1Z4
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Alan Brelsford, Fax: +41 21 692 41 65; E-mail: Alan.Brelsford@unil.ch

Abstract

Several animal species have recently been shown to have hybrid origins, but no avian examples have been documented with molecular evidence. We investigate whether the Audubon’s warbler (Dendroica auduboni), one of four visually distinct species in the yellow-rumped warbler complex, has originated through hybridization between two other species in this group, the myrtle warbler (D. coronata) and black-fronted warbler (D. nigrifrons). Analysis of nuclear amplified fragment length polymorphism (AFLP) and sequence markers shows that Audubon’s warblers are genetically intermediate and carry a mixture of alleles otherwise found only in one or the other of their putative parental species. Audubon’s warblers also carry two deeply divergent mitochondrial DNA lineages, each shared with only one putative parental form. Broad clines between Audubon’s and black-fronted warblers in AFLP markers call into question the validity of these two forms as full species; nevertheless, our results suggest that the Audubon’s warbler probably originated through hybridization between two long-diverged species. It is likely that more cases of avian species of hybrid origin will be revealed by surveys of variation in nuclear DNA and other traits.

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