Do discrepancies between microsatellite and allozyme variation reveal differential selection between sea and lagoon in the sea bass (Dicentrarchus labrax)?

Authors

  • C. Lemaire,

    Corresponding author
    1. Laboratoire Génome, Populations, Interactions, Université Montpellier II, CNRS UPR 9060, Station Méditerranéenne de l’Environnement Littoral, 1 Quai de la Daurade, 34200 Sète, France,
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  • G. Allegrucci,

    1. Dipartimento di Biologia, Università degli Studi di Roma ‘Tor Vergata’, Via della Ricerca Scientifica, I-00133 Roma, Italy,
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  • M. Naciri,

    1. Laboratoire Génome, Populations, Interactions, Université Montpellier II, CNRS UPR 9060, Station Méditerranéenne de l’Environnement Littoral, 1 Quai de la Daurade, 34200 Sète, France,
    2. Laboratoire de Biologie et Zoologie Générale, Université Mohamed V. av. Ibn Battouta, BP 1014, Rabat, Morocco,
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  • L. Bahri-Sfar,

    1. Laboratoire Génome, Populations, Interactions, Université Montpellier II, CNRS UPR 9060, Station Méditerranéenne de l’Environnement Littoral, 1 Quai de la Daurade, 34200 Sète, France,
    2. Laboratoire de Biologie et Parasitologie marines, Faculté des Sciences de Tunis, Campus Universitaire, Tunis, Tunisia,
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  • H. Kara,

    1. Laboratoire Génome, Populations, Interactions, Université Montpellier II, CNRS UPR 9060, Station Méditerranéenne de l’Environnement Littoral, 1 Quai de la Daurade, 34200 Sète, France,
    2. Département de Biologie Marine, Résidence ‘Le Belvédère’, Rte du Cap de Garde, Annaba, 2300, Algeria
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  • F. Bonhomme

    1. Laboratoire Génome, Populations, Interactions, Université Montpellier II, CNRS UPR 9060, Station Méditerranéenne de l’Environnement Littoral, 1 Quai de la Daurade, 34200 Sète, France,
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C. Lemaire. Fax: +33-4-67-46-33-99; E-mail: clemaire@univ-montp2.fr

Abstract

In the present study the genetic structure of Dicentrarchus labrax (14 samples from the Mediterranean) was analysed at six microsatellite loci, in order to test the hypothesis that some enzymatic loci undergo selection between marine and lagoon habitat. Eight of the 14 samples were analysed at both microsatellite and allozyme markers. The analysis of the genetic variation among the Mediterranean samples showed that (i) FST values obtained with the six microsatellite loci were much smaller than those obtained with the 28 allozymes and (ii) microsatellite loci seemed to reflect more the geographical proximity than an ecological one. Thirteen enzymatic loci exhibited moderate to high values compared with microsatellites. This was interpreted as evidence that these allozymes are non-neutral. However, only six loci seemed to be implicated in differentiation between marine and lagoon samples, the causes of selection being unknown for the others. A possible scenario of population dynamics of the sea bass between marine and lagoon habitat is suggested.

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