Estimating the Gene Pool Condition in Natural Populations of Invertebrates in the Fragmented Landscape of Moscow and Moscow Region with Special Reference to Bush Snail Bradybaena fruticum Mull.

Abstract

Using shrub snail Bradybaena fruticum Müll (20 populations) as a model, we were the first in Russia and in the world to develop a system of urban ecological genetic monitoring of the gene pool of an invertebrate species. The results of isozyme polymorphism studies in shrub snail populations showed a dramatic (up to 70%) reduction in genetic diversity in small isolates from the urbanized environment as compared to large natural populations. In urban populations, genetic diversity parameters were demonstrated to be lower than in natural ones: the mean heterozygosity per locus was reduced up to 0.08 (0.15-0.20 in natural populations); the mean allele number, to 1.9 (2.7 in natural populations); and the number of polymorphic loci, to four, i.e., 2.2-fold (nine in natural populations). In Moscow district, the number of polymorphic loci also decreased to five in the population subjected to anthropogenic pressure. The changes in the population gene pool (as shown by the number of polymorphic loci) were different in Moscow and Moscow district. The percentage of populations with the number of polymorphic loci as low as four to six was 76.9 in Moscow and 23.1% in Moscow district. The gene pool quality of 80% of the urban snail populations was estimated as unsatisfactory, and in half of them, as critical. The main reason for these changes seems to be genetic drift accompanied by inbreeding, caused by fragmentation of the range and reduction in the abundance of populations of the species, due to the anthropogenic pressure. The results of the study were employed in the program of the Moscow government for restoring the gene pools of endangered animals species on the preserved territories of the city.