Understanding admixture patterns in supplemented populations: a case study combining molecular analyses and temporally explicit simulations in Atlantic salmon

Authors

  • Charles Perrier,

    Corresponding author
    1. Agrocampus Ouest, Rennes, France
    2. INRA, UMR 1313 Animal Genetics and Integrative Biology, Domaine de Vilvert, Jouy-en-Josas, France
    3. Département de Biologie, Institut de Biologie Intégrative et des Systèmes, Université Laval, Québec, QC, Canada
    • INRA, UMR 0985 Ecology and Health of Ecosystems, Rennes, France
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  • Jean-Luc Baglinière,

    1. INRA, UMR 0985 Ecology and Health of Ecosystems, Rennes, France
    2. Agrocampus Ouest, Rennes, France
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  • Guillaume Evanno

    1. INRA, UMR 0985 Ecology and Health of Ecosystems, Rennes, France
    2. Agrocampus Ouest, Rennes, France
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Correspondence

Charles Perrier, Département de Biologie, Institut de Biologie Intégrative et des Systémes, Université Laval, Québec, Qc, Canada.

Tel.: +1 418 656 2131 extn. 8455

fax: +1 418 656 7176

e-mail: charles5perrier@gmail.com

Abstract

Genetic admixture between wild and introduced populations is a rising concern for the management of endangered species. Here, we use a dual approach based on molecular analyses of samples collected before and after hatchery fish introduction in combination with a simulation study to obtain insight into the mechanisms of admixture in wild populations. Using 17 microsatellites, we genotyped pre- and post-stocking samples from four Atlantic salmon populations supplemented with non-native fish to estimate genetic admixture. We also used individual-based temporally explicit simulations based on realistic demographic and stocking data to predict the extent of admixture. We found a low admixture by hatchery stocks within prestocking samples but moderate to high values in post-stocking samples (from 12% to 60%). The simulation scenarios best fitting the real data suggested a 10–25 times lower survival of stocked fish relative to wild individuals. Simulations also suggested relatively high dispersal rates of stocked and wild fish, which may explain some high levels of admixture in weakly stocked populations and the persistence of indigenous genotypes in heavily stocked populations. This study overall demonstrates that combining genetic analyses with simulations can significantly improve the understanding of admixture mechanisms in wild populations.

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