Combining phylogeography and landscape genetics to infer the evolutionary history of a short-range Mediterranean relict, Salamandra salamandra longirostris

Abstract

Examining historical and contemporary processes underlying current patterns of genetic variation is key to reconstruct the evolutionary history of species and implement conservation measures promoting their long-term persistence. Combining phylogeographic and landscape genetic approaches can provide valuable insights, especially in regions harboring high levels of biodiversity that are currently threatened by climate and land cover changes, like southern Iberia. We used genetic (mtDNA and microsatellites) and spatial data (climate and land cover) to infer the evolutionary history and contemporary genetic connectivity in a short-range endemic salamander subspecies, Salamandra salamandra longirostris, using a combination of ecological niche modelling, phylogeographic, and landscape genetic analyses. Ecological-based analyses support a role of the Guadalquivir River Basin as a major vicariant agent in this taxon. The lower genetic diversity and greater differentiation of peripheral populations, together with analyses of climatically stable areas throughout time, suggest the persistence of a population in the central part of the current range since the Last Inter Glacial [LIG; ~ 120,000–140,000 years BP], and a micro refugium in the eastern end of the range. Habitat heterogeneity plays a major role in shaping patterns of genetic differentiation in S. s. longirostris, with forests representing key areas for its long-term persistence under scenarios of environmental change. Our study stresses the importance of maintaining population genetic connectivity in low-dispersal organisms under rapidly changing environments, and will inform management plans for the long-term survival of this evolutionarily distinct Mediterranean endemic.