Slug species- and population-specific effects on the end points of the Slug Mucosal Irritation test.

The Slug Mucosal Irritation test seems to be a promising method for the evaluation of the local tolerance of products applied to the mucosa. Furthermore, the Slug Mucosal Irritation test is a reliable method to classify chemicals accurately into three eye irritation categories based on the mucus production and the score for tissue damage. Until now the slug Arion lusitanicus collected in Belgium was always used as test organism. The present study investigated the effects of the slug population and species on the end points of the test and on the eye irritation classification. For this purpose, the eye irritation/damage test procedure and eye reference chemicals were used. Comparison of the results of one Belgian and two Swiss A. lusitanicus populations indicated that the geographic and ecological origins of slug populations did neither influence the mucus production, nor the score for tissue damage. Slug species-specific effects on the test end points were investigated by comparing the data of Belgian Limax flavus with corresponding data of Belgian A. lusitanicus. L. flavus produced more mucus than A. lusitanicus, so that the mucus production cut-off values had to be increased. Therefore, the results indicated that the test procedure and prediction model have to be optimised and validated, if other slug species are used instead of A. lusitanicus.

Population genetics and identity of an introduced terrestrial slug: Arion subfuscus s.l. in the North-East USA (Gastropoda, Pulmonata, Arionidae).

Several European species of the terrestrial slug genus Arion have been introduced into North America. A case in point is the species complex A. subfuscus s.l. which has become one of the most abundant slug taxa in North America. In Europe this complex consists of at least two cryptic species, viz. A. fuscus and A. subfuscus s.s., the latter of which is further subdivided in five strongly divergent mtDNA lineages (A. subfuscus S1-S5). In order to determine which of these A. subfsucus s.l. taxa are present in the NE USA and in order to assess their population genetic structure, we compared mtDNA, nDNA and allozyme variation between populations from the NE USA and Europe. Our results show that (1) at least A. subfuscus S1 has become successfully established in the NE USA, (2) founder effects are the most likely explanation for the loss of a large amount of molecular genetic variation in populations from the NE USA (i.e. a loss of 96% of the 16S rDNA haplotypes, 67% of the ITS1 alleles and 46% of the alleles at polymorphic allozyme loci), and (3) part of the remaining genetic variation in NE USA populations was probably due to multiple introductions from the British Isles and the European mainland, and the hybrid structure of most of these source populations. Apparently, the extreme loss of molecular genetic variation in this introduced species has not prevented it from successfully establishing and spreading in novel environments.

Rangewide phylogeography of a terrestrial slug in Europe: evidence for Alpine refugia and rapid colonization after the Pleistocene glaciations.

Intraspecific phylogeographical patterns largely depend on the life history traits of a species. Especially species with a high degree of cold tolerance, limited requirements towards habitat preferences, and relatively low active dispersal capacities may have responded in a different way to the Pleistocene climatological fluctuations than the majority of taxa studied so far. To evaluate this possibility, we studied Arion fuscus (Muller, 1774), a common and widespread European terrestrial slug, from 88 locations (N = 964). Sequence variation was assessed for fragments of the mitochondrial 16S rDNA and COI genes by means of single-strand conformation polymorphisms (SSCP) and subsequent DNA sequencing. Additionally, eight allozyme loci were scored in 843 individuals. Phylogenetic analysis revealed the presence of two major evolutionary lineages, one in the Balkan region and another in the Alps and the rest of Europe. The sequence divergence between the two lineages was limited (3.3%), but gene flow between the regions was absent, suggesting that the two regions have been isolated since the late Pliocene or early Pleistocene. Allozyme differentiation among geographical regions and mitochondrial DNA (mtDNA) lineages was low. The geographical patterns observed in our data showed that (i) haplotype and nucleotide diversities are very low in northern Europe, suggesting that single haplotypes rapidly colonized large areas; (ii) recently expanded haplotype clades have restricted distribution ranges, suggesting that current gene flow is low; and (iii) genetic diversity in the Alps is much higher than in other regions and estimated past gene flow from the Eastern Alps to other regions was high, suggesting that this was a refugial zone during the Pleistocene. This full-range phylogeography suggests the existence of an alternative refugial zone, situated north of the refugial areas currently recognized in most other taxa.