Specific features of phenetic structure of the terrestrial snail <Emphasis Type="Italic">Cepaea vindobonensis</Emphasis> (Pulmonata; Helicidae) in urbanized and natural populations

The phenetic structure of natural and urbanized populations of the terrestrial snail Cepaea vindobonensis has been studied with respect to polymorphism in the shell-band color and pattern. It is noted that C. vindobonensis snails populating different artificial habitats in the city of Nikolaev and its suburbs are characterized by a higher level of both intra-and interpopulation diversity with respect to the type of this polymorphism. In addition, urban populations show a very wide range of variation in the frequencies of particular morphs or their groups. Conversely, natural populations are characterized by a more uniform frequency structure with respect to polymorphism of the shell banding pattern.     

Dispersal of Land Snails of the Genus Xeropicta Monterosato, 1892 (Gastropoda; Pulmonata; Hygromiidae)

Data on the parameters of migration of two land snails of the genus Xeropicta are presented. In relatively homogeneous habitats, the locomotor activity of these mollusks is relatively high: they can travel for up to 300 cm per day, with neither the phenotype nor size of the shell having any significant influence on the level of dispersal. The snails prefer to travel westward and southward, but the distances covered by individuals moving in different directions are similar. No connection between the directions or distances of movement on two successive days has been observed.     

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

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.