A vagrant clone in a peregrine species: Phylogeography, high clonal diversity and geographical distribution in the earthworm Aporrectodea trapezoides (Dugès, 1828)

The peregrine lumbricid Aporrectodea trapezoides is originally from the Palaearctic region but is distributed worldwide. Little is known about its clonal diversity or the existence of a pattern of biogeographical diversification of clones. This study aimed to explore the evolutionary history of A. trapezoides by analysing the mitochondrial (COI and COII) and nuclear (28S rRNA and histone H3) DNA sequences of individuals collected in 11 different countries. High clonal diversity was found for this species, with thirty-seven clones clearly divided into two distinct lineages (I and II). The marked biogeographical boundary between these lineages corresponds to the line separating the Eurosiberian and Mediterranean climates in North Spain. Clone 1 was shared by one-third of the earthworms. While this clone was found in most of the sampled localities, the rest of the clones showed geographically-restricted distributions. This clone may have originated in the Mediterranean area of Central Spain. As it was obviously introduced in Australia and it was found in locations occupied by members of both lineages, we hypothesise that it may have also been introduced in other countries and that it could be a general-purpose genotype able to adapt to a wide range of niches.

► We studied the phylogeography of the peregrine earthworm Aporrectodea trapezoides.
► Two geographically-distinct lineages were found: Eurosiberian and Mediterranean.
► Both lineages do not represent different species after the 4X rule for species delimitation.
► Most of the clones were geographically-restricted; one was very common and widely distributed.
► We conclude that this clone has a vagrant behaviour.