The land-snail species of Cochlicopa (Gastropoda: Pulmonata: Cochlicopidae): presentation of taxon-specific allozyme patterns, and evidence for a high level of self-fertilization

Genetic differentiation in the four nominal species C. nitens (Gallenstein, 1848), C. lubricella (Porro, 1838), C. lubrica (O. F. Müller, 1774) and C. repentina Hudec, 1960 was studied by investigating 21 isoenzyme loci. Allozymic markers exist, which clearly separate the first three taxa from each other, including in sympatric areas. By contrast, C. repentina and C. lubrica exhibit almost no isozymic differentiation and therefore, C. repentina should not be considered as a separate species, but as a member of C. lubrica sensu lato. The high frequency of homozygotes within all populations of all species shows that self-fertilization is the main breeding system of Cochlicopa. Genetic relationships between the various populations were inferred with different tree-constructing methods. In all phenograms, populations of C. nitens appear in one distinct cluster, whereas the grouping of C. lubricella changes when different clustering-procedures are used. Therefore, it remains unclear whether the three populations of C. lubricella have a common origin or whether they are polyphyletic with at least two independent ancestors.