Genetic variability in geographic populations of the natterjack toad (Bufo calamita)
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Date
2012
Authors
Oromí Farrús, Neus
Richter-Boix, A
Sanuy i Castells, Delfí
Fibla Palazón, Joan
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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 [Ma] and
expected heterozygosity [HE]) obtained from our results and those published in
the literature. The low level of genetic differentiation found between populations
of B. calamita (Fst ranging from 0.0115 to 0.1018) and the decreases in
genetic diversity with altitude (Ma from 13.6 to 8.3, HE 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.
Citation
Journal or Serie
Ecology and Evolution, 2012, vol.2, núm. 8, p. 2018-2026