Phylogeography and genetic lineages of Aporrectodea rosea (Lumbricidae, Annelida)

Aporrectodea rosea (Savigny, 1826) is a cosmopolitan earthworm widespread throughout the Holarctic. The available data on A. rosea genetic diversity (mainly from the Mediterranean region) suggests that this species can be divided into the Mediterranean and the Eurosiberian lineages. In this study we tested molecular variation within this species from the Northeastern Palearctic, namely from Russia, Belarus, and Kazakhstan, using nuclear and mitochondrial sequences. We detected previously unknown genetic diversity within the Eurosiberian lineage: basal representatives of this group from the south of Belarus were only distantly related to the rest of the lineage. This suggests that after the split of A. rosea into the Mediterranean and the Eurosiberian lineages, the latter diversified in eastern Europe with subsequent recolonization of the Mediterranean region. The paleogeographic history of this species is thus more complex than it was thought earlier. We found that A. rosea significantly increased its range over the last two decades, now being found in West Siberia; genetic diversity there is low compared to European Russia and Belarus. Compared to the closely related A. caliginosa, A. rosea had lower genetic diversity, probably caused by fewer dispersal events.