High levels of population subdivision in a morphologically conserved Mediterranean toad (Alytes cisternasii) result from recent, multiple refugia: evidence from mtDNA, microsatellites and nuclear genealogies

Authors

  • H. GONÇALVES,

    1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, 4485-661 Vairão, and Departamento de Zoologia e Antropologia – Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
    2. Museo Nacional de Ciencias Naturales, CSIC, c/José Gutiérrez Abascal, 2, 28006 Madrid, Spain
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  • I. MARTÍNEZ-SOLANO,

    1. Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, 75 N Eagleville Rd., Unit 3043, Storrs, CT 06269-3043, USA
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  • R. J. PEREIRA,

    1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, 4485-661 Vairão, and Departamento de Zoologia e Antropologia – Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
    2. Museum of Vertebrate Zoology, 3101 Valley Life Sciences Bldg., Berkeley, CA 94720-3160, USA
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  • B. CARVALHO,

    1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, 4485-661 Vairão, and Departamento de Zoologia e Antropologia – Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
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  • M. GARCÍA-PARÍS,

    1. Museo Nacional de Ciencias Naturales, CSIC, c/José Gutiérrez Abascal, 2, 28006 Madrid, Spain
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  • N. FERRAND

    1. CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, 4485-661 Vairão, and Departamento de Zoologia e Antropologia – Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
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H. Gonçalves, Fax: +351 252661780;
E-mail: hgoncalves@mail.icav.up.pt

Abstract

Pleistocene glaciations often resulted in differentiation of taxa in southern European peninsulas, producing the high levels of endemism characteristic of these regions (e.g. the Iberian Peninsula). Despite their small ranges, endemic species often exhibit high levels of intraspecific differentiation as a result of a complex evolutionary history dominated by successive cycles of fragmentation, expansion and subsequent admixture of populations. Most evidence so far has come from the study of species with an Atlantic distribution in northwestern Iberia, and taxa restricted to Mediterranean-type habitats remain poorly studied. The Iberian Midwife toad (Alytes cisternasii) is a morphologically conserved species endemic to southwestern and central Iberia and a typical inhabitant of Mediterranean habitats. Applying highly variable genetic markers from both mitochondrial and nuclear genomes to samples collected across the species’ range, we found evidence of high population subdivision within A. cisternasii. Mitochondrial haplotypes and microsatellites show geographically concordant patterns of genetic diversity, suggesting population fragmentation into several refugia during Pleistocene glaciations followed by subsequent events of geographical and demographic expansions with secondary contact. In addition, the absence of variation at the nuclear β-fibint7 and Ppp3caint4 gene fragments suggests that populations of A. cisternasii have been recurrently affected by episodes of extinction and recolonization, and that documented patterns of population subdivision are the outcome of recent and multiple refugia. We discuss the evolutionary history of the species with particular interest in the increasing relevance of Mediterranean refugia for the survival of genetically differentiated populations during the Pleistocene glaciations as revealed by studies in co-distributed taxa.

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