INTRA- AND INTERPOPULATION SHELL VARIABILITY OF TERRESTRIAL MOLLUSC BREPHULOPSIS CYLINDRICA FROM THE NORTHERN BLACK SEA COAST REGION

Abstract

The study of the limits of variability of terrestrial mollusks in natural populations and the distribution of the whole spectrum of variability into genetic and ecological components is one of the most important tasks of evolutionary ecology and ecogenetics of these organisms. The authors who studied the malacofauna of this species have repeatedly pointed to the wide range of geographical (interpopulation) variability of conchological characteristics of mollusks of the genus Brephulopsis.

Of particular interest are the features of the populations of the Northern Black Sea coast of Ukraine, where this species is widespread and occupies a variety of geoclimatic characteristics of the territory. The population of the species was first discovered near Lake Solonets-Tuzla near the village Rybakivka of the Berezansky district of the Mykolaiv region.

Based on the measurements data of the shell from the first detected population of B. cylindrica from the vicinity of Lake Solonets-Tuzla (C), the limits of variability of traits were determined.  The maximum indicator of the width of the shell from the population of Solonets-Tuzla was the largest among those known in the region, thus influencing the conchological characteristics of the species as a whole.

It has been confirmed that shell indicators are under close genetic control within each individual population. In terms of apex height, no significant differences found between all studied populations. Apex indicators are under a high level of genetic control.

The study of conchological indicators of each newly identified population of terrestrial mollusks allows clarifying the identification indicators of the species. Microevolutionary processes in B. cylindrica populations of the Northern Black Sea coast are active, specific and depend on localization factors. The variety of conditions contributes to the intensification of evolutionary processes in populations and the acquisition of significant differences in conchological characteristics. There is a tendency to approximate the absolute values of shell height in populations located in similar geoclimatic conditions that affect growth processes.