Phylogeographic analyses reveal recent dispersal and multiple Wolbachia infections of the bright-eyed ringlet Erebia oeme within the European mountain systems

The genus Erebia comprises numerous species in Europe. Due to preference of cold environments, most species have disjunct distributions in the European mountain systems. However, their biogeographical patterns may differ significantly. The Bright-eyed ringlet Erebia oeme is widespread in high-altitude grasslands of the European high mountains, hence showing a disjunct distribution pattern. Over its distribution, E. oeme shows high morphological variability indicating pronounced intraspecific differentiation. We analysed two mitochondrial (COI, Cytb) and eight nuclear markers as well as the Wolbachia surface protein-coding gene (WSP). A total of four lineages were identified: two Balkan lineages, one Slovenian lineage as well as one lineage containing all other individuals (Alps, Massif Central, Pyrenees). COI data only indicate a fifth lineage in the southern Carpathians. The region of origin of E. oeme is most likely the western Balkans. From here, E. oeme spread to the eastern Balkan area and further to the southern Carpathians as well as to Slovenia, from where it rapidly crossed the Alps to Massif Central and Pyrenees. Wolbachia was found to be highly prevalent with multiple strains, partly within one population. However, recent Wolbachia impact on the mitochondrial DNA and consequently influence on the intraspecific genetic structure was not detected.