The Andes mountains constitute without doubt one of the main factors that have promoted Neotropical diversification. However, the role of other highland regions in the southern cone of South America has been barely studied. We analyzed the level of endemism in the avifauna of the Central mountain range in Córdoba province, an isolated high region in central Argentina, to evaluate the possible effect of its geographic isolation from the Andes. There are 11 species in this region that include subspecies endemic to the area, but all of them have been designated due to differences in morphology (mainly coloration) and none has been evaluated yet using molecular markers. We performed the first genetic analyses of these species and, combining fresh tissue samples with toe pad samples, were able to analyze mitochondrial DNA sequences (cytochrome c oxidase subunit I and cytochrome b) of 7 of these species and an assortment of other 10 species that could have cryptic differentiation in the area. The analysis of genetic divergence and haplotype networks have shown that in 5 (Cinclodes atacamensis, Muscisaxicola rufivertex, Asthenes sclateri, Catamenia inornata and Phrygilus unicolor) of the 7 species with endemic subspecies in the Central mountain range, the specimens from this area possessed some degree of differentiation from those of other subspecies of Argentina. In the 2 other species results suggested a lack of isolation in this area (Phrygilus plebejus and Sturnella loyca, being the latter the only one occupying lowland areas and therefore having a continuous, not disjunct distribution). None of the species without endemic subspecies showed signs of isolation in the region, although both Turdus chiguanco and Troglodytes aedon presented high intraspecific variation. While further analyses including more molecular markers, morphological characters and vocalizations are needed, these results suggest that most species that have disjunct distributions, with a population in the Central mountain range of Córdoba province isolated geographically from the Andes, show differentiated genetic lineages in this region that suggest an evolutionary isolation from other populations of the species.
