Range expansion and hybridization in Round Island petrels (Pterodroma spp.): evidence from microsatellite genotypes

Authors

  • RUTH M. BROWN,

    1. Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK
    2. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
    3. Mauritian Wildlife Foundation, Vacoas, Mauritius
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  • RICHARD A. NICHOLS,

    1. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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  • CHRIS G. FAULKES,

    1. School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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  • CARL G. JONES,

    1. Mauritian Wildlife Foundation, Vacoas, Mauritius
    2. Durrell Wildlife Conservation Trust, Les Augrès Manor, Trinity, Jersey JE3 5BP, Channel Islands
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  • LEANDRO BUGONI,

    1. Institute of Biomedical and Life Sciences, Graham Kerr Building, University of Glasgow, G12 8QQ, UK
    2. Instituto de Ciências Biológicas, Fundação Universidade Federal do Rio Grande—FURG, CP 474, CEP 96.650-900, Rio Grande, RS, Brazil
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  • VIKASH TATAYAH,

    1. Mauritian Wildlife Foundation, Vacoas, Mauritius
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  • DADA GOTTELLI,

    1. Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK
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  • WILLIAM C. JORDAN

    1. Institute of Zoology, Zoological Society of London, Regents Park, London NW1 4RY, UK
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Ruth M. Brown, Fax: 0207 586 2870;
E-mail: ruth.brown@ioz.ac.uk

Abstract

Historical records suggest that the petrels of Round Island (near Mauritius, Indian Ocean) represent a recent, long-distance colonization by species originating from the Atlantic and Pacific Oceans. The majority of petrels on Round Island appear most similar to Pterodroma arminjoniana, a species whose only other breeding locality is Trindade Island in the South Atlantic. Using nine microsatellite loci, patterns of genetic differentiation in petrels from Round and Trindade Islands were analysed. The two populations exhibit low but significant levels of differentiation in allele frequencies and estimates of migration rate between islands using genetic data are also low, supporting the hypothesis that these populations have recently separated but are now isolated from one another. A second population of petrels, most similar in appearance to the Pacific species P. neglecta, is also present on Round Island and observations suggest that the two petrel species are hybridizing. Vocalizations recorded on the island also suggest that hybrid birds may be present within the population. Data from microsatellite genotypes support this hypothesis and indicate that there may have been many generations of hybridization and back-crossing between P. arminjoniana and P. neglecta on Round Island. Our results provide an insight into the processes of dispersal and the consequences of secondary contact in Procellariiformes.

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