WITHIN-POPULATION STRUCTURE HIGHLIGHTED BY DIFFERENTIAL INTROGRESSION ACROSS SEMIPERMEABLE BARRIERS TO GENE FLOW IN ANGUILLA MARMORATA

Authors

  • Pierre-Alexandre Gagnaire,

    1. Institut des Sciences de l’Evolution (ISEM UMR 5554 CNRS-UMII), Université Montpellier II, CC 065, Place E. Bataillon, 34095 Montpellier cedex 05, France
    2. E-mail: pagagnai@univ-montp2.fr
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  • Yuki Minegishi,

    1. Institut des Sciences de l’Evolution (ISEM UMR 5554 CNRS-UMII), Université Montpellier II, CC 065, Place E. Bataillon, 34095 Montpellier cedex 05, France
    2. Ocean Research Institute, University of Tokyo, 1–15-1 Minamidai, Nakano-ku, Tokyo 164–8639, Japan
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  • Saliha Zenboudji,

    1. Institut des Sciences de l’Evolution (ISEM UMR 5554 CNRS-UMII), Université Montpellier II, CC 065, Place E. Bataillon, 34095 Montpellier cedex 05, France
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  • Pierre Valade,

    1. Association Réunionnaise de Développement de l’Aquaculture, Centre des Eaux Douces, Les Sables, 97427 Etang Salé, Ile de La Réunion, France
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  • Jun Aoyama,

    1. Ocean Research Institute, University of Tokyo, 1–15-1 Minamidai, Nakano-ku, Tokyo 164–8639, Japan
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  • Patrick Berrebi

    1. Institut des Sciences de l’Evolution (ISEM UMR 5554 CNRS-UMII), Université Montpellier II, CC 065, Place E. Bataillon, 34095 Montpellier cedex 05, France
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Abstract

In the marine environment, differential gene exchange between partially reproductively isolated taxa can result in introgression that extends over long distances due to high larval dispersal potential. However, the degree to which this process contributes to interlocus variance of genetic differentiation within introgressed populations remains unclear. Using a genome-scan approach in the Indo-Pacific eel Anguilla marmorata, we investigated the degree of interpopulation genetic differentiation, the rate of introgression, and within-population genetic patterns at 858 AFLP markers genotyped in 1117 individuals. Three divergent populations were identified based on clustering analysis. Genetic assignments of individuals revealed the existence of different types of hybrids that tended to co-occur with parental genotypes in three population contact zones. Highly variable levels of genetic differentiation were found between populations across the AFLP markers, and reduced rates of introgression were shown at some highly differentiated loci. Gene flow across semipermeable genetic barriers was shown to generate spatial introgression patterns at some loci which define within-population structure over long distances. These results suggest that differential introgression in subdivided populations may be relevant when interpreting spatial variation patterns displayed by outlying loci in other marine fish populations.

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