Phylogeography of the green turtle, Chelonia mydas, in the Southwest Indian Ocean

Authors

  • J. BOURJEA,

    1. Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer) de La Réunion, Rue Jean Bertho, BP 60, 97 822 Le Port Cedex, Ile de La Réunion, France,
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  • S. LAPÈGUE,

    1. Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer), Laboratoire de Génétique et Pathologie, Ronce-les-Bains, 17 390 La Tremblade, France,
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  • L. GAGNEVIN,

    1. CIRAD UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical, 3P, 7 chemin de l’IRAT, 97410 Saint Pierre, La Réunion,
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  • D. BRODERICK,

    1. School of Integrative Biology,
    2. Department of Primary Industries and Fisheries, Queensland Biosciences Precinct, Level 6 North Tower, University of Queensland, St Lucia, Queensland 4072, Australia,
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  • J. A. MORTIMER,

    1. Ministry of Environment & Natural Resources, PO Box 445, Victoria, Mahe, Seychelles,
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  • S. CICCIONE,

    1. Centre d’Etude et de Découverte des Tortues Marines de La Réunion (CEDTM), BP 40, 97898 Saint Leu Cedex, La Réunion, France
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  • D. ROOS,

    1. Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer) de La Réunion, Rue Jean Bertho, BP 60, 97 822 Le Port Cedex, Ile de La Réunion, France,
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  • C. TAQUET,

    1. Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer) de La Réunion, Rue Jean Bertho, BP 60, 97 822 Le Port Cedex, Ile de La Réunion, France,
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  • H. GRIZEL

    1. Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer) de La Réunion, Rue Jean Bertho, BP 60, 97 822 Le Port Cedex, Ile de La Réunion, France,
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Jérôme Bourjea, Fax: (00 262) 262 43 36 84; E-mail: jerome.bourjea@ifremer.fr

Abstract

Patterns of mitochondrial DNA (mtDNA) variation were used to analyse the population genetic structure of southwestern Indian Ocean green turtle (Chelonia mydas) populations. Analysis of sequence variation over 396 bp of the mtDNA control region revealed seven haplotypes among 288 individuals from 10 nesting sites in the Southwest Indian Ocean. This is the first time that Atlantic Ocean haplotypes have been recorded among any Indo-Pacific nesting populations. Previous studies indicated that the Cape of Good Hope was a major biogeographical barrier between the Atlantic and Indian Oceans because evidence for gene flow in the last 1.5 million years has yet to emerge. This study, by sampling localities adjacent to this barrier, demonstrates that recent gene flow has occurred from the Atlantic Ocean into the Indian Ocean via the Cape of Good Hope. We also found compelling genetic evidence that green turtles nesting at the rookeries of the South Mozambique Channel (SMC) and those nesting in the North Mozambique Channel (NMC) belong to separate genetic stocks. Furthermore, the SMC could be subdivided in two different genetic stocks, one in Europa and the other one in Juan de Nova. We suggest that this particular genetic pattern along the Mozambique Channel is attributable to a recent colonization from the Atlantic Ocean and is maintained by oceanic conditions in the northern and southern Mozambique Channel that influence early stages in the green turtle life cycle.

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