Evolution of mosaic hybrid zone between invasive and endemic species of Cyprinidae through space and time

Authors

  • CAROLINE COSTEDOAT,

    Corresponding author
    1. Unité Evolution Génome Environnement (EGEE), EA 3781, Case 36, Université de Provence, 3 Place Victor Hugo, 13331 Marseille, Cedex 3, France
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  • NICOLAS PECH,

    1. Unité Evolution Génome Environnement (EGEE), EA 3781, Case 36, Université de Provence, 3 Place Victor Hugo, 13331 Marseille, Cedex 3, France
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  • MARIE-DOMINIQUE SALDUCCI,

    1. Unité Evolution Génome Environnement (EGEE), EA 3781, Case 36, Université de Provence, 3 Place Victor Hugo, 13331 Marseille, Cedex 3, France
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  • REMI CHAPPAZ,

    1. Unité Evolution Génome Environnement (EGEE), EA 3781, Case 36, Université de Provence, 3 Place Victor Hugo, 13331 Marseille, Cedex 3, France
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  • ANDRE GILLES

    1. Unité Evolution Génome Environnement (EGEE), EA 3781, Case 36, Université de Provence, 3 Place Victor Hugo, 13331 Marseille, Cedex 3, France
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E-mail: costedoa@up.univ-mrs.fr

Abstract

Hybridization phenomena can be considered in different ways. Hybridization studies can be used to elucidate some aspects of speciation and adaptation. However, hybridization may be a threat to endemic species. Here, we studied bidirectional introgression between two sympatric species of Cyprinidae: Chondrostoma toxostoma toxostoma and C. nasus nasus. Analysis of morphology, allozymes and mtDNA sequences revealed that the hybridization between these two cyprinids takes different forms in the same river. The mosaic hybrid zone (so called because of the absence of a simple cline) appeared to be partitioned due to the proportions of the two species along a spatial scale. The proportion of each hybrid group in this zone was unstable over a 5-year period. We propose various protection/conservation states for the C. t. toxostoma populations based on the level of introgressive hybridization and the genetic structure of both species in ‘pure’ populations. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 135–155.

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