Inter-island divergence within Drosophila mauritiana, a species of the D. simulans complex: Past history and/or speciation in progress?

Authors

  • D. LEGRAND,

    1. Laboratoire Evolution, Génomes et Spéciation, UPR 9034, CNRS, 91198 Gif-sur-Yvette Cedex, France and Université Paris-Sud 11, 91405 Orsay Cedex, France
    2. UMR 7204, MNHN-CNRS-UPMC, 55 rue Buffon, 75005 Paris, France
    3. Station d’Ecologie Expérimentale du CNRS, USR 2936, 09200 Moulis, France
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  • T. CHENEL,

    1. Laboratoire Evolution, Génomes et Spéciation, UPR 9034, CNRS, 91198 Gif-sur-Yvette Cedex, France and Université Paris-Sud 11, 91405 Orsay Cedex, France
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  • C. CAMPAGNE,

    1. Laboratoire Evolution, Génomes et Spéciation, UPR 9034, CNRS, 91198 Gif-sur-Yvette Cedex, France and Université Paris-Sud 11, 91405 Orsay Cedex, France
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  • D. LACHAISE,

    1. Laboratoire Evolution, Génomes et Spéciation, UPR 9034, CNRS, 91198 Gif-sur-Yvette Cedex, France and Université Paris-Sud 11, 91405 Orsay Cedex, France
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    • Daniel Lachaise deceased in 2006.

  • M.-L. CARIOU

    1. Laboratoire Evolution, Génomes et Spéciation, UPR 9034, CNRS, 91198 Gif-sur-Yvette Cedex, France and Université Paris-Sud 11, 91405 Orsay Cedex, France
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Marie-Louise Cariou, Fax: 33 (0)1 6982 3736; E-mail: Marie-Louise.Cariou@legs.cnrs-gif.fr

Abstract

Speciation with gene flow may be more common than generally thought, which makes detailed understanding of the extent and pattern of genetic divergence between geographically isolated populations useful. Species of the Drosophila simulans complex provide a good model for speciation and evolutionary studies, and hence understanding their population genetic structure will increase our understanding of the context in which speciation has occurred. Here, we describe genetic diversity and genetic differentiation of two distant populations of D. mauritiana (Mauritius and Rodrigues Islands) at mitochondrial and nuclear loci. We surveyed the two populations for their mitochondrial haplotypes, eight nuclear genes and 18 microsatellite loci. A new mitochondrial type is fixed in the Rodrigues population of D. mauritiana. The two populations are highly differentiated, their divergence appears relatively ancient (100 000 years) compared to the origin of the species, around 0.25 MYA, and they exhibit very limited gene flow. However, they have similar levels of divergence from their sibling, D. simulans. Both nuclear genes and microsatellites revealed contrasting demographic histories between the two populations, expansion for the Mauritius population and stable population size for the Rodrigues Island population. The discovery of pronounced geographic structure within D. mauritiana combined to genetic structuring and low gene flow between the two island populations illuminates the evolutionary history of the species and clearly merits further attention in the broad context of speciation.

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