Genetic comparisons between North American and European populations of Lumbricus terrestris L.

The common earthworm Lumbricus terrestris L is an invasive species that was introduced to North America by European settlers. Subsequently, earthworms have been distributed by human activity, invaded a wide geographic range and changed previously earthworm-free ecosystems. In the present study we analyzed seven European and four North American populations from a wide geographic range at three formerly described nuclear microsatellite markers. All three markers produced multi-banding patterns and marker presence versus absence was scored in 88 narrow size intervals. Similar levels of genetic variation were observed for North American (Nei's gene diversity = 0.058, Shannon's I = 0.100) and European populations (Nei's gene diversity = 0.064, Shannon's I = 0.104). North American populations showed a higher similarity among each other than European populations in accordance with their recent introduction to North America. The relatively high level of genetic variation in North American populations and the high similarity among each other suggest their establishment from genetically diverse founder populations and rapid human-mediated population expansion. The source regions in Europe are still unclear from this analysis. (C) 2012 Elsevier Ltd. All rights reserved.