Stability in the Balkans: phylogeography of the endemic Greek stream frog, Rana graeca

Abstract

Abstract We still have little knowledge concerning the phylogeography of amphibians and reptiles from the Balkan Peninsula compared with the other two Mediterranean peninsulas. This raises concerns for endemic taxa from these peninsulas, because it might interfere with further conservation efforts. Here we focus on the endemic Greek stream frog (Rana graeca) and reconstruct its biogeography and evolutionary history. Using four genetic markers (Cytb, 16S, COI and BDNF) in > 350 sequences covering the whole distribution range, we conducted phylogenetic, demographic and ecological niche analyses, which revealed the phylogeography of this species. Surprisingly, this examination of R. graeca reveals a very shallow level of intraspecific genetic variability through the Balkans, with two main, statistically supported lineages having a partly sympatric distribution. The most variable marker was Cytb, which showed 19 haplotypes in 123 analysed sequences in the whole species distribution area. Here presented genetic data, together with the environmental niche projection and demographic analyses suggest that R. graeca was probably affected only marginally by climatic oscillations, with the Hellenides as the most suitable area for the occurrence of the species in different geological periods. This is consistent with the observed genetic diversity, which is mostly related to these mountains. Although the species shows a certain level of phenotypic variability and ecological preferences, this might be related to species plasticity affected by the micro-climatic conditions in small areas, which merits further research. Comparing phylogeography of other amphibian and reptile species in the Balkans, we showed that the observed pattern represents a new view on the phylogeography of the Balkan herpetofauna.