Limited gene flow and high genetic diversity in the threatened Betic midwife toad (Alytes dickhilleni): evolutionary and conservation implications

Abstract

Habitat fragmentation may involve a loss of genetic diversity and increments the vulnerability to species persistence. It could be a particular issue when coupled with other negative factors as the predicted climatic changes and the emergence of infectious diseases. In Southern Iberian Peninsula several endemic amphibian species have confined and fragmented distributions, including the Betic midwife toad Alytes dickhilleni. Herein, we present the first range-wide assessment of genetic diversity and structure in this species, using mitochondrial and microsatellite data. A mitochondrial fragment of the ND4 gene was amplified for 65 individuals and a set of 20 microsatellite loci, specifically developed for this species, was genotyped for 490 individuals from several sampling sites distributed across the species entire range. While both markers revealed high genetic diversity, only for microsatellites a marked genetic substructure was apparent. Our results evidence low levels of gene flow, suggesting the persistence of the species in fragmented habitats for several generations and a very limited connectivity between most of mountain ranges. The high diversity within A. dickhilleni populations could help to respond to the emergence of new diseases and to the predicted effects of climatic changes in Southeastern Iberian Peninsula. We hypothesize that the lack of gene flow is due to the absence of available breeding habitats and recommend that future management efforts of A. dickhilleni include the creation and maintenance of aquatic breeding habitats in a way that most of genetic diversity is preserved.