Communication: Luise Kruckenhauser (genetics), Laura Zopp (anatomy, morphology, histology)
The hermaphroditic land snail Cylindrus obtusus
(Draparnaud, 1805) is an endemic of the Austrian Alps. Restricted to high elevations (1600 to 2500 m asl; Bisenberger et al. 1999, Duda et al. 2010) it has a rather patchy distribution extending from Schneeberg to Großglockner. Previous qualitative analyses of anatomical traits of the distal female genital tract revealed two geographically distinct groups. Western populations show pairwise mucus glands of equal size whereas in eastern populations these glands are conspicuously shortened and (sometimes) asymmetrically to different degrees (Schileyko et al. 1997). To find out whether these anatomical differences reflect a genetic differentiation, which might be an indication for distinct glacial refugia, we investigate a partial sequence of the mitochondrial COI gene and 9 microsatellite loci (Arthofer et al. 2010) from samples covering the whole distribution range of the species. The COI sequences indicate a geographic differentiation between eastern, central and western populations. However, genetic distances are small (max. 1.7 %). The microsatellite analysis reveals a high differentiation between the populations implying restriction of gene flow. Remarkably, nearly all individuals from the eastern populations are homozygous at all microsatellite loci (although different alleles were found within populations). The most plausible explanation for this finding is an altered mode of reproduction. Further investigations shall elucidate whether this lack of heterozygotes is caused by selfing and if so, why it occurs at such a high frequency. In a morphological study two different approaches are employed: Quantitative measurements of the mucus glands and the stylophore are taken from more than 70 individuals collected from 16 populations. Preliminary results confirm quantitatively the east-west division previously described. A comparative histological investigation of the mucus glands will be performed to assess the functionality of these structures in both groups.
In an additional analysis we try to elucidate the phylogenetic relationships of C. obtusus within the Helicidae on the basis of various molecular markers.
First results were presented at several scientific meetings.