Inferring the roles of vicariance, climate and topography in population differentiation in Salamandra algira (Caudata, Salamandridae)

Integrating information from species occurrence data, environmental variables and molecular markers can provide valuable insights about the processes of population persistence and differentiation. In this study, we present the most comprehensive overview of the evolutionary history of the North African salamander Salamandra algira (Caudata, Salamandridae) to date, including analyses of climatic and topographical variables, and sequences of two mitochondrial and two nuclear DNA fragments, with a special focus on Algerian populations, under-represented in previous studies. Coalescent-based phylogenetic analyses of mtDNA data recover four well-supported population groups corresponding to described subspecies, with a western clade including populations in north-western Morocco (with two subclades corresponding to the subspecies tingitana and splendens), and an eastern clade including populations from north-eastern Morocco (subspecies spelaea) and Algeria (subspecies algira). Inferred split times between major clades date back to the Miocene, with additional splits within each major clade in the Plio-Pleistocene. Present climatic (aridity) and topographical factors account for geographical discontinuities across population groups and help identify potential areas of secondary contact between clades corresponding to the subspecies tingitana and splendens in the Rif mountains in Morocco. Niche analysis indicates the absence of phylogenetic signal in the use of environmental space in this species.