Genetic polymorphism of Plantago major populations from the radioactive and chemical polluted areas

Abstract

The variability of nine microsatellite loci was studied for Plantago major L. populations from radioactive (East-Ural Radioactive Trace, EURT) and chemical (Karabash Copper Smelter, KCS) contaminated areas (Urals, Russia). The absorbed dose rates in the EURT area were 178–1455 times higher than background, and the indices of the total toxic load in the KCS area were 13–42 times higher than background values. In total, 65 alleles were identified in P. major populations, while the number of alleles per locus in the EURT and KCS samples was lower than in the background samples. The expected heterozygosity in all loci significantly exceeded the observed, indicating a high level of inbreeding. The largest number of rare alleles (11–21) was found in background samples, of which 3–7 alleles were private. In the technogenically disturbed zones, 8–11 rare alleles (1–2 private) were noted. The Bayesian analysis (K = 3) showed that no unique groups were found in any of the areas; descendants of all founders (pioneers) were represented in each population, but in different proportions. However, only 4.1% of the variability was distributed between local P. major populations (FST = 0.041) and 95.9% was concentrated within the samples. A pairwise comparison revealed genetic differentiation between all EURT samples. In the KCS area, there was no significant differentiation in pairs of samples that were at a distance of 3–4 km from each other. For samples from the KCS and background sites, the Mantel test showed a statistically significant relationship between geographical and genetic distances, therefore, the intensity of migration flows between these areas is high. For samples from the EURT and background areas, no such dependence was found. In both impact zones, P. major populations showed reduced genetic diversity. This article discusses the causes of this phenomenon.