Shell Banding and Color Polymorphism of the Introduced Snail Cepaea nemoralis (Gastropoda, Helicidae) in Lviv, Western Ukraine

Th e shell coloration was studied in more than three thousand adults of the grove snail, Cepaea nemoralis (Linnaeus, 1758), from 15 colonies discovered in 2019–2020 in Lviv City and in the immediate vicinity of its south-ern administrative border (Zubra village). In most colonies, relatively light phenotypes prevailed: most oft en P00000, less oft en Y00000 or Y00300. In total, more than a third of the collected specimens had the phenotype P00000. Great variability of the phenotypic and genetic structure of this introduced species in the study area was demonstrated, which usually does not have a clear connection with the locations of colonies or with the shading of habitats. Th is may be due to both random factors (founder eff ect, gene drift in recently formed colonies), and the relative youth of the colonies. In the future, the obtained data can be used to monitor possible long-term changes in the phenotypic composition of the investigated colonies to assess the potential eff ect of selective factors on this composition, fi rst of all, climatic selection outside the natural range of C. nemoralis.

Geographical and chronological variability of the conchological characters of the mollusc Fruticicola fruticum (O.F.Müller, 1774) (Gastropoda; Pulmonata; Bradybaenidae) in the Eastern Europe

The population structure of the terrestrial mollusk (Gastropoda, Pulmonata, Bradybaenidae) in different landscapes of Eastern Europe on the basis of conchological measurements, including morphometric parameters and color variants was studied. For all morphometric parameters used, statistically significant differences were found between the studied populations. At the same time, the shell size are determined not by zonal characteristics, but by microbiotopic conditions. Changes in the frequency of shell phenotypes in Fr. fruticum populations are probably of a multifactorial nature. The ratio of different color variants can be caused by the influence of radiation, cyclic fluctuations of climatic factors, succession changes in biotopes, and gene drift.

Evolution of darwinism. Synthetic theory of evolutions: 1926 – 1975 years

The process of combining Darwinism and genetics, which entered the history of biology as a synthetic theory of evolution, is considered.Key words: synthetic theory of evolution, neo-Darwinism, the concept of a biological species, population genetics, genetic polymorphism, the theory of dominance, gene drift.

Gene Differentiation in Pacific Salmon (Oncorhynchus sp.): Facts and Models with Reference to Pink Salmon (O. gorbuscha)

Analyzing population genetic data usually involves examining relationships among populations followed by analysis of the distribution of genetic variability. Genetic relationships are often depicted with multidimensional scaling or trees constructed from genetic distances; genetic variation within and among populations is partitioned using gene diversity measures such as FST or GST. Genetic distances or gene diversity are often used to estimate influences of gene drift, migration, and/or selection on observed gene differentiation. We used allozyme data for pink salmon populations to examine the theoretical models available for estimating magnitudes of these factors in Pacific salmon populations. The models included (1) mutation and gene drift; (2) mutation and migration; (3) migration and gene drift; and (4) gene drift, migration, and selection. These models suggest that gene drift and migration are probably important at the lowest levels of population hierarchy, but even very small forces such as weak heterogeneous selection and low migration levels may be important at higher levels. The accuracy of some estimates should be questioned because for many situations appropriate models are either not yet available or are not sufficiently refined. Also, the dynamic genetic structure of salmon populations makes it unlikely that the steady state assumed for many theoretical models has obtained.