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The limits of mtDNA phylogeography: complex patterns of population history in a highly structured Iberian lizard are only revealed by the use of nuclear markers

Authors

  • R. GODINHO,

    1. CIBIO — Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, 4485-661 Vairão, Portugal,
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      We would like to dedicate this paper to Prof. Godfrey Hewitt due to his insightful and outstanding work in the study of hybrid zones, that predicted the patterns and processes we are now describing for many species in Southern European Refugia.

  • E.G. CRESPO,

    1. Centro de Biologia Ambiental e Departamento de Biologi Animal, Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal,
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    • §

      We would like to dedicate this paper to Prof. Godfrey Hewitt due to his insightful and outstanding work in the study of hybrid zones, that predicted the patterns and processes we are now describing for many species in Southern European Refugia.

  • N. FERRAND

    1. CIBIO — Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, 4485-661 Vairão, Portugal,
    2. Departamento de Zoologia e Antropologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007 Porto, Portugal
    Search for more papers by this author
    • §

      We would like to dedicate this paper to Prof. Godfrey Hewitt due to his insightful and outstanding work in the study of hybrid zones, that predicted the patterns and processes we are now describing for many species in Southern European Refugia.


Raquel Godinho, Fax: +351 252 661780; E-mail: rgodinho@mail.icav.up.pt

Abstract

Phylogeographic analyses based on the sole use of the mitochondrial DNA (mtDNA) molecule reveal only a small part of the evolutionary history of a species or a set of related species. In this study, we have combined the application of slow- and fast-evolving nuclear markers (proteins and microsatellites, respectively) together with the analysis of two-gene genealogies to further understand the history of the Iberian endemic Schreiber's green lizard, Lacerta schreiberi, a species for which a well established phylogeographical scenario is available. In sharp contrast with the observation of four divergent and almost allopatric mtDNA clades, our nuclear data revealed how two groups of populations diverged, persisted and began to admix along the mountains of the Iberian Central System. In addition, the combination of mtDNA and nuclear data showed how the core area of the species distribution responded to ice ages, first by relatively old processes of population expansion to the south followed by episodes of contraction that are at the origin of present-day isolates, and more recently by a postglacial expansion to the Iberian Northwest where new habitats were made available after climatic amelioration. Taken together with recently published results for a variety of other organisms, our results suggest that complex processes of fragmentation, expansion and admixture can only be properly addressed through the use of several and complementary types of molecular markers. Finally, we also suggest that southern European refugia are both hotspots and melting pots of genetic diversity.

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