Genetic variability in geographic populations of the natterjack toad ( Bufo calamita)

Authors

  • N. Oromi,

    1. Escola Tècnica Superior d'Enginyeria Agrària, Departament of Producció Animal (Fauna Silvestre), University of Lleida, Lleida, Spain
    2. Campus de Ciències de la Salut, Edifici Biomedicina I, Department of Basic Medical Sciences, Universitat de Lleida-IRBLleida, Lleida, Spain
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  • A. Richter-Boix,

    1. Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
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  • D. Sanuy,

    1. Escola Tècnica Superior d'Enginyeria Agrària, Departament of Producció Animal (Fauna Silvestre), University of Lleida, Lleida, Spain
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  • J. Fibla

    Corresponding author
    1. Campus de Ciències de la Salut, Edifici Biomedicina I, Department of Basic Medical Sciences, Universitat de Lleida-IRBLleida, Lleida, Spain
    • Escola Tècnica Superior d'Enginyeria Agrària, Departament of Producció Animal (Fauna Silvestre), University of Lleida, Lleida, Spain
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  • The project was financed by Spain's Ministry of Science and Innovation (CGL2009-12767-C02-01) and the regional administration (Diputació) of the province of Lleida.

Correspondence

Joan Fibla, Campus de Ciències de la Salut, Edifici Biomedicina I, Department of Basic Medical Sciences, Universitat de Lleida-IRBLleida, Av. Rovira Roure, 80, 25198 Lleida, Spain. Tel: +34-973702473; Fax: +34-973702426; E-mail: joan.fibla@cmb.udl.cat

Abstract

Across altitudinal and latitudinal gradients, the proportion of suitable habitats varies, influencing the individual dispersal that ultimately can produce differentiation among populations. The natterjack toad ( Bufo calamita) is distributed across a wide geographic range that qualifies the species as interesting for a geographic analysis of its genetic variability. Five populations of B. calamita in the Sierra de Gredos (Spain) were studied in an altitudinal gradient ranging from 750 to 2270 m using microsatellite markers. In addition, we analyzed the latitudinal genetic variation in B. calamita within a global European distribution using genetic diversity parameters (mean number of alleles per locus [M a ] and expected heterozygosity [H E ]) obtained from our results and those published in the literature. The low level of genetic differentiation found between populations of B. calamita (F st ranging from 0.0115 to 0.1018) and the decreases in genetic diversity with altitude (M a from 13.6 to 8.3, H E from 0.82 to 0.74) can be interpreted by the combined effects of discontinuous habitat, produced mainly by the high slopes barriers and geographic distance. In the latitudinal gradient, genetic diversity decreases from south to north as a consequence of the colonization of the species from the Pleistocene refugium. We conclude that the genetic variability in B. calamita along its wide altitudinal and latitudinal geographic distribution mainly reflects the colonization history of the species after the last glacial period.

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