Introgression and Differentiation of the Invasive SlugArion vulgarisfrom NativeA. ater

Abstract

ABSTRACT The large arionid slug Arion vulgaris is an invasive pest dispersing through large parts of Europe and causing considerable damage in gardens, horticulture and agriculture. It is also possible that this so-called “Iberian slug” has an impact on Norwegian ecosystems, displacing or hybridizing with the native black slug Arion ater. The taxonomy of the large arionids is complex and confusing, encompassing different anatomical forms and colour varieties. The present study integrates, for the first time, coloration, ligula morphology, genital morphometry, nuclear and mitochondrial DNA in order to differentiate the large arionids found in Norway, A. vulgaris, A. ater and A. rufus. These data revealed a clear separation between A. vulgaris and A. ater based on the morphology of the genitalia and mtDNA. However, introgression with the red slug A. rufus was apparent in approximately half of the A. ater specimens analysed, evidenced by ligula morphology, mitochondrial and nuclear DNA. In addition, the mito...