Genetic diversity of an invasive earthworm, Lumbricus terrestris, at a long-term trading crossroad, the Champlain Valley of Vermont, USA.

The invasive European earthworm, Lumbricus terrestris, is now widely distributed in North America. This success may result from high genetic diversity derived from multiple introductions from founder sources across Europe. Using a mitochondrial gene (COI) and microsatellite markers, L. terrestris from seven sites in the Champlain Valley of Vermont USA were scored for genetic diversity and population structure. This region has been a trading crossroads for centuries, thus likely to have received earthworms from multiple origins. COI sequences matched those reported for L. terrestris from Scotland, France, Austria, Denmark, Sweden, and Norway, and 2–5 haplotypes were found at each site. Genetic diversity (microsatellites) was great for each site, but not notably greater than for earthworm populations in general, possibly because there may be allele size homoplasy, or some restriction in the number of alleles possible at any locus. The earthworms were genetically differentiated among the Vermont study sites, even those 0.6–13 km distant. These results support the view that L. terrestris is a successful invasive earthworm because multiple introductions provided ample genetic variation for natural selection and local differentiation among locations in North America. Last, a large number of microsatellite markers is provided, including suggested PCR programs, for free use by future researchers. [ABSTRACT FROM AUTHOR]