Genetic structure of the water frog (<i>Pelophylax esculentus</i> complex) populations in the south of the Central Russian Upland

Abstract

BACKGROUND: The water frog (Pelophylax esculentus complex) is hybrid in composition. In view of the fact that a large number of data on the species composition of the water frog and very scarce material on the genetic structure of populations are available in the literature, we aimed to analyze the genetic structure of populations of the water frog in the southern part of the Middle Russian upland, which was one of the refugia for many species during the glacial epoch and the center of dispersion in the postglacial time, based on DNA microsatellite markers.
 MATERIALS AND METHODS: The study involved 36 local populations. DNA variability was analyzed by multiplex SSR-PCR. Seven loci (Res 14, Res 15, Res 17, Res 22, Rrid059A, Rrid082A, and Rrid171A) were used for amplification. Fragment analysis of PCR products was performed on an ABI PRISM 3500 automated capillary DNA sequencer (Applied Biosystems, USA).
 RESULTS: The total number of alleles detected ranged from 13 to 41. The effective number of alleles (Ae) averaged 4.569 0.219, the Chenon index (I) 1.567 0.04, level of expected heterozygosity (Не) 0.68 0.01. According to Wrights model, the greatest contribution to genetic variability is made by the heterogeneity of individuals within populations, some of which are of a hybrid nature (Fis = 0.281 0.069, Fit = 0.413 0.053, Fst = 0.180 0.017). The average indicator of the intensity of gene exchange between populations (Nm) was 1.212 0.142 individuals per generation. The calculation of the effective abundance using the LD method indicates a high level of viability of the studied groups of the frogs.
 CONCLUSION: The results demonstrated a high level of genetic diversity and viability of most of the studied groups, which, due to the intense gene exchange between them, can represent a single panmictic population. The data of the genetic analysis support the active adaptation of P. esculentus complex to living in an urbanized environment.