Evidence for geographic substructuring of mtDNA variation in the East European Hermit beetle (Osmoderma barnabita)

The genus Osmoderma is a flagship taxon of invertebrate conservation in Europe and encompasses a complex of four accepted species. While species limits amongst Osmoderma have been intensively studied, patterns of intraspecific variation are poorly known. In this paper, the authors focus on clarifying the phylogeographic structure of the East European Osmoderma barnabita using samples from Croatia to Finland. Samples of hind legs were collected from populations in Latvia and Finland (n=186) and combined with previously-published sequences from GenBank and museum specimens (n=10). In a partial sequence of the mitochondrial COI gene (759 bp), 26 closely related haplotypes were found. Beetle samples from different parts of Europe were distinct and showed no overlap in haplotype composition. The solitary population of Finland proved to be monomorphic and all 97 individuals sampled here belonged to a single haplotype unique to this region. The results suggest the Northern parts of Eastern Europe to be dominated by a single COI haplotype to which most of the other haplotypes are linked by one or two mutations. The pattern seems to reflect a founder effect or a strong bottleneck event. While O. barnabita is widely distributed over Eastern Europe, current patterns of mitochondrial genetic diversity appear influenced by population history and little homogenisation by ongoing gene flow. From a conservation perspective, the patterns suggest that regional populations might need to be managed as subunits and that the population of Finland may be affected by low genetic diversity