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Tug of war between continental gene flow and rearing site philopatry in a migratory bird: the sex-biased dispersal paradigm reconsidered

Authors

  • NICOLAS LECOMTE,

    1. Département de Biologie and Centre d’Études Nordiques, Université Laval, Québec, QC, Canada G1V 0A6
    2. Département de Biologie and Québec-Océan, Université Laval, Québec, QC, Canada G1V 0A6
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  • GILLES GAUTHIER,

    1. Département de Biologie and Centre d’Études Nordiques, Université Laval, Québec, QC, Canada G1V 0A6
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  • JEAN-FRANÇOIS GIROUX,

    1. Groupe de Recherche en Écologie Comportementale et Animale, Département des Sciences Biologiques, Université du Québec à Montréal, PO Box 8888, Stn Centre-Ville, Montréal, QC, Canada H3C 3P8
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  • EMMANUEL MILOT,

    1. Département de Biologie and Québec-Océan, Université Laval, Québec, QC, Canada G1V 0A6
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  • LOUIS BERNATCHEZ

    1. Département de Biologie and Québec-Océan, Université Laval, Québec, QC, Canada G1V 0A6
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Nicolas Lecomte, Department of Biology, University of Tromsø, N-9037 Tromsø, Norway. Fax: +4777646333; E-mail: nicolas.lecomte@ib.uit.no

Abstract

Nonrandom dispersal has been recently advanced as a mechanism promoting fine-scale genetic differentiation in resident populations, yet how this applies to species with high rates of dispersal is still unclear. Using a migratory species considered a classical example of male-biased dispersal (the greater snow goose, Chen caerulescens atlantica), we documented a temporally stable fine-scale genetic clustering between spatially distinct rearing sites (5–30 km apart), where family aggregates shortly after hatching. Such genetic differentiation can only arise if, in both sexes, dispersal is restricted and nonrandom, a surprising result considering that pairing occurs among mixed flocks of birds more than 3000 km away from the breeding grounds. Fine-scale genetic structure may thus occur even in migratory species with high gene flow. We further show that looking for genetic structure based on nesting sites only may be misleading. Genetically distinct individuals that segregated into different rearing sites were in fact spatially mixed during nesting. These findings provide new, scale-dependent links between genetic structure, pairing, and dispersal and show the importance of sampling different stages of the breeding cycle in order to detect a spatial genetic structure.

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