Introduced exotic earthworms now occur in every biogeographic region in
all but the driest or coldest habitat types on Earth. The global distribution
of a few species (e.g.,
but now approximately 120 such peregrine species are recognized to
be widespread from regional to global scales, mainly via human activities.
Species adapted to human transport and to colonization of disturbed habitats
are most widespread and are the principal invasive species.We identify
a number of endogenous and exogenous factors that may contribute to the
successful establishment and spread of peregrine species. Quantification of
these factors may help to determine why certain species become invasive
while others do not. Recent advances in theory and modeling of biological
invasions and in molecular techniques should prove fruitful in improving our
understanding of invasive earthworms, as well as in predicting their impacts
on ecosystems.