Small effective population sizes in a widespread selfing species, Lymnaea truncatula (Gastropoda: Pulmonata)

Authors

  • C. MEUNIER,

    Corresponding author
    1. Centre d’Etude sur le Polymorphisme des Micro-organismes (UMR CNRS-IRD 9926), Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, F-34394 Montpellier Cedex 1, France,
    2. Génétique et Evolution des Populations Végétales (UMR 8016), Université Lille 1, SN2, 59655 Villeneuve d’Ascq Cedex, France,
      C. Meunier. E-mail: cecile.meunier@Univ-lille1.fr
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  • S. HURTREZ-BOUSSES,

    1. Centre d’Etude sur le Polymorphisme des Micro-organismes (UMR CNRS-IRD 9926), Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, F-34394 Montpellier Cedex 1, France,
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  • P. DURAND,

    1. Centre d’Etude sur le Polymorphisme des Micro-organismes (UMR CNRS-IRD 9926), Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, F-34394 Montpellier Cedex 1, France,
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  • D. RONDELAUD,

    1. Facultés de Médecine et de Pharmacie, UPRES EA 3174, 2 rue du Docteur Raymond Marcland, 87025 Limoges Cedex, France
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  • F. RENAUD

    1. Centre d’Etude sur le Polymorphisme des Micro-organismes (UMR CNRS-IRD 9926), Institut de Recherche pour le Développement, 911 Avenue Agropolis, BP 64501, F-34394 Montpellier Cedex 1, France,
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C. Meunier. E-mail: cecile.meunier@Univ-lille1.fr

Abstract

We present here a spatial and temporal population genetic survey of a common freshwater snail, also a predominantly selfing species, Lymnaea truncatula. The rate of genetic diversity loss was quantified by estimating the effective size (Ne) of the snail populations, using two different methods. A temporal survey allowed estimation of a variance effective size of the populations, and a spatial survey allowed the estimation of an inbreeding effective size, from two-locus identity disequilibria estimates. Both methods were consistent and provided low Ne values. Drift due to (i) high amounts of selfing and (ii) fluctuations in population sizes because of temporary habitats, and also selection coupled to genome-wide linkage disequilibria, could explain such reductions in Ne. The loss of genetic diversity appears to be counterbalanced only very partially by low apparent rates of gene flow.

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