Introgressive hybridization between two Iberian endemic cyprinid fish: a comparison between two independent hybrid zones

Authors

  • M. A. ABOIM,

    1. Centro de Biologia Ambiental, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Lisboa, Portugal
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    • 1

      These authors have contributed equally to this work.

  • J. MAVÁREZ,

    1. Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Apartado 20632, Caracas, Venezuela
    2. IBIS (Institut de Biologie Intégrative et des Systèmes) Université de Laval, QC, Canada
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    • 1

      These authors have contributed equally to this work.

  • L. BERNATCHEZ,

    1. IBIS (Institut de Biologie Intégrative et des Systèmes) Université de Laval, QC, Canada
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  • M. M. COELHO

    1. Centro de Biologia Ambiental, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, Lisboa, Portugal
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Jesús Mavárez, Centro de Ecología, Instituto
Venezolano de Investigaciones Científicas, Apartado 20632, Caracas 1020-A, Venezuela.
Tel.: +58 (0)212 5041886; fax: +58 (0)212 5041088;
e-mail: mavarez@gmail.com

Abstract

Pseudochondrostoma duriense and Achondrostoma oligolepis are two Iberian endemic cyprinid fish species that occur in sympatry over most of their distribution range and that are suspected to hybridize in nature. Here, we employed a combination of mitochondrial and microsatellite markers to explore the extent of introgressive hybridization between these fishes. Two natural hybrid zones were identified in different river basins. Introgression was bi-directional and both hybrid zones consisted mostly of parental genotypes/phenotypes (i.e. bimodal hybrid zones). Yet, they appeared to differ in the extent and direction of introgression, which supports the view that they constitute independent outcomes of different hybridization processes probably influenced by environmental features. Several discordances were found between mtDNA and microsatellite results, suggesting that this hybridization process has complex consequences and illustrating the importance of using independent markers to define accurately the hybrid status of individuals in the presence of high levels of backcrossing.

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