Genetic Structure in Different Subsequent Generations of Sexually Mature Rapana venosa Mollusks from the Same Biotope

Two Rapana venosa (R. venosa) samples representing different age groups from the same biotope (Odes’ka zatoka) were compared, using allozyme analysis, by their genetic structure. The genotypes were tested at 19 loci of nine enzymes. The genepool of the collected R. venosa samples was generally characterized by genetic disequilibrium and the elevated level of actual heterozygosity at the studied polymorphic loci (on average, at 16–18%). Sexually mature mollusk generations belonging to different age groups from the same biotope had a comparably lower relatedness between each other than the mollusk samples from different aquatic areas of the Black Sea. However, the genetic distance between the studied R. venosa groups was at the level of local populations in all cases. The analysis of the contribution made by evolutionary factors has shown the leading role of migrations in the formation of the R. venosa genepool in the northern part of the Black Sea.