Genetic divergence and phylogeography of the alpine plant taxonOnobrychis transsilvanica(Fabaceae)

Abstract

Although the Carpathians represent one of the main elements of the European Alpine System and an important area of endemism, only a few phylogeographic studies concerning this region have focused on the detailed intraspecific variation in alpine plant species. Using two molecular marker systems, we (1) aimed to elucidate the controversy concerning the status of the endemic Carpathian taxon Onobrychis transsilvanica Simonk. in relation to the more widespread Onobrychis montana DC. and (2) determined the phylogeographic structure of O. transsilvanica within the Carpathians. For O. transsilvanica, our data suggest either a recent postglacial speciation with incomplete lineage sorting or genetic divergence followed by subsequent continuous gene flow during the glacial period. The genetic structure of the complex does not support O. transsilvanica as a distinct species from O. montana. Within the Carpathians, the extant populations of O. transsilvanica comprise two major allopatric lineages, which have been isolated from each other for a long period of time. Unexpectedly, the major genetic break was not in line with a classical biogeographical boundary in the Carpathians but rather separated a group from the southwestern edge of the mountains. We also discovered an additional divergent haplotype lineage, with weaker genetic support, within the O. transsilvanica populations.