| In this thesis, I examined the breeding systems and taxonomy of two hermaphroditic land gastropod taxa: viz. the subgenus Carinarion and the genus Zonitoides. For this, I combined allozyme electrophoresis, isoelectric focusing, random amplified polymorphic DNA, morphometry and breeding experiments.;Carinarion mainly reproduces uniparentally in NW Europe and consists of a number of homozygous multilocus genotypes (MLGs). However, in Central Europe, outcrossing is frequent and at least two species ( Arion fasciatus and A. silvaticus) appear paraphyletic, whereas the third species (A. circumscriptus) has a somewhat distinct position. Neither morphometrical, nor egg laying data provided convincing taxonomic differences between the species. Only esterases yielded species specific patterns, yet, esterases are strongly influenced by the type of food consumed and therefore should be suspect as population genetic marker. It might be better to consider Carinarion as an agamospecies which, due to its uniparental reproduction in NW Europe has evolved into a number of morphotypes and MLGs. Some of these MLGs may represent 'general purpose genotypes' since they were found in a wide variety of habitat types.;Two Zonitoides species are common in Europe, viz. Z. nitidus and Z. excavatus. Both species show a remarkable polymorphisin in the male genitalia. In the majority of individuals, the male genitalia are only weakly developed (hemiphallic animals), whereas a minority of animals have normally developed male genitalia (euphallic animals). Hemiphallic animals are not capable of donating sperm and can only receive sperm. Euphallic animals can both act as spermdonor or spermreceiver. Despite the proportion of euphallic animals in a population may be as high as 20%, all individuals reproduce uniparentally and as a consequence, both species consist of a number of MLGs. The functional significance of phally polymorphism in Zonitoides remains to be investigated. |
