Microevolution in Solatopupa landsnails (Pulmonata Chondrinidae): genetic diversity and founder effects

Enzyme variability at 28 presumptive gene loci was studied, by standard starch gel electrophoresis, in 30 populations belonging to the five recognized species of the landsnail Solatopupa from its entire NW Mediterranean range.
Six genetically differentiated groups can be identified among the 30 populations sampled. These are distinguished by two to 19 diagnostic loci, different levels of genetic variability and populations genetics. They are also significantly different as far as the D values are considered. There is no evidence of gene flow among them. Genetically inferred groups correspond in four cases to morphologically distinguished species. In contrast, S. similis , as identified by morphological features, is likely to be a complex of at least two cryptic species.
Populations and species of Solatopupa are characterized by: high fixation of alternative alleles both within and between species; medium-lo-low levels of genie variation; heterozygote deficiency; sharp genetic differentiation among population within species; restricted gene flow; and high genetic distances. Genetic variability is partly associated with climatic factors related to moisture.
Both deterministic and stochastic processes may play a part in the genetic differentiation of Solatopupa snails. Founder events seem to be the main factor affecting the genetic structure of populations and perhaps also speciation. Solatopupa populations display many attributes of populations that may be expected to undergo speciation events involving reorganization of the whole genome after a founder event.