Genetic structure of the continuous and ephemeral populations of the land snail Brephulopsis Cylindrica (Gastropoda; Pulmonata; Enidae)

Abstract

Background. One may hypothesize that the land snail B. cylindrica distributed in small, isolated, ephemeral populations tends to decrease genetic polymorphism level (e. g., observed heterozygosity for allozyme loci). Thus, the present study aims at estimating the levels of allozyme polymorphism in the land snail B. cylindrica from continuously distributed populations and ephemeral ones. Materials and methods. In the Nikolaev urbanised areas 9 samples were taken and studied electrophoretically for four polymorphic allozyme system. In the Dubki, Neftebasa and Park Pobedy populations (continuously distributed populations - group N 1) the two localities, situated about 50 m apart, were sampled. While only single locality were investigated from the Kosmos, Morechodnaya and Mira populations (ephemeral populations - group N 2). Statistical analysis of electrophoretic data was performed with the program GenAIEx version 6.0. Results. In general, significant differences with respect to the level of genetic polymorphism between the continuous and ephemeral populations of the land snail B. cylindrical have not discovered on the basis of allozymes loci. However, when analyzing the distribution of multilocus allozyme genotypes in the populations studied, we have received fundamentally different results. In general, ephemeral populations differed from the continuous ones with respect to the frequency of studied multilocus allozyme genotypes although one populations has been disrupted this rule (Dubki-2). Conclusion. Based on these results it is concluded that small, isolated (including, urban) populations tend to reduce the level of genetic diversity, due to the manifestation of genetic and stochastic processes (genetic drift or founder effect). In addition, an important consequence of the latter there is a relatively high rate of unpredictable change genotypic profiles of such settlements, which leads to a significant increase in the level of genetic differentiation between them.

Genome-wide Assessment Elucidates Connectivity and the Evolutionary History of the Highly Dispersive Marine Invertebrate Littoraria Flava (Littorinidae:Gastropoda)

“…There was no clear structuring within transects based on the delimitated sites, which is inconsistent with a previous finding [26]. The differences could be due the different mutation rates of SNPs and allozyme markers [28,35,36], or because allozymes are expressed phenotypes involved in metabolic functions and therefore could be undergoing some type of natural selection [4,6,29,37]. The observed microgeographic structure within the transect did not exhibit an isolation by distance model, i.e., differentiation among samples does not build up with an increase in spatial study scale ( Fig.…”

“…It has been widely assumed that pelagic larval phases facilitate dispersal over broad scales, in turn promoting high levels of gene flow and poor genetic structure. Nonetheless, several studies have demonstrated that the above presumption is not entirely true [3][4][5][6][7][8][9][10].…”

“…Highly heterogeneous environments, such as rocky shore intertidal zones, present physical and biological gradients over short geographical distances. Such heterogeneity can be measured based on several predictors [14,15] and could favor different genotypes across different microhabitats [4,6,16]. The littorinids are a taxonomic group of herbivorous gastropods that inhabit global intertidal zones.…”

Patterns of spatio-temporal variation in land snails: a multi-scale approach

“…Thus, while there were distinct genotypic differences among individuals from different populations, within the population Dubky there was a considerable intra-population differentiation between the sampling sites, which were spatially separated from each other by a relatively short distance. However, in the other two populations no such differentiation was observed (KramarenKo & Snegin 2015).…”

Genetic structure analysis of the alien mollusk Stenomphalia ravergiensis (Mollusca, Gastropoda, Pulmonata) population in Belgorod (Russia)

“…Allozyme analysis of invasive populations of the terrestrial snail Theba pisana in Australia revealed considerable reduction of genetic diversity (Johnson, 1988). Allozyme marker-based studies of continuous and ephemeral populations of the invasive species Brephulopsis cylindrica in the town of Nikolaev (Ukraine) also showed that small isolated populations of this terrestrial mollusk (including urbanized populations) tended toward a decrease in genetic diversity related to the occurrence of stochastic genetic processes (gene drift or founder effect) (Kramarenko and Snegin, 2015). However, the intragroup variability decrease was accompanied by interpopulation distance increase in this species (Fst = 0.281), this being in agreement with the shifting balance theory of evolution (Wright, 1970).…”