Phenetic population structure of the land snail Helix albescens (Gastropoda, Pulmonata, Helicidae) in the Crimea

Abstract

The polymorphism of shell banding pattern has been studied in Crimean populations of the land snail H. albescens. The results show that snails from different regions of the Crimea are characterized by specific types of shell polymorphism, the differences between them concerning mainly the number of observed shell morphs rather than their occurrence frequency. In particular, the proportion of snails with darkly colored shells increases in relatively cool habitats. However, among the microevolutionary processes determining the type and degree of polymorphism in H. albescens populations, a major role is also played by stochastic genetic phenomena, because the species exists in semi-isolated colonies with low effective abundance and high risk of local extinction.