The Eastern Urals Radioactive Trace as a Source of Genetic Diversity in Rodent Populations in Adjacent Territories

The polymorphism of the gene cytochrome b (cytb) fragment of mitochondrial DNA (mtDNA) and the migratory activity of red-backed voles (Myodes rutilus Pallas, 1779) were first investigated in a zone of local radioactive contamination, the Eastern Urals radioactive trace zone (EURT). The results suggest high haplotype diversity in both samples from the EURT zone and the adjacent territory (9–10 km) compared with the reference one (220 km). The nucleotide diversity and mean number of paired differences between haplotypes proved to be the greatest in voles from the adjacent site with the radiation level corresponding to the background values. Our assumption about the association of genetic diversity with rodent migrations from the EURT zone was verified in field experiments employing group marking of the population with the biomarker rhodamine B. Migrants (males and females) of different functional status were revealed at background sites. Long-distance movement of 9500 m is the maximum known for M. rutilus. The EURT zone is a source of genetic diversity in rodent populations in adjacent territories due to interpopulation gene flow patterns (transmission by migrants of the radiation-induced effects). MtDNA can serve as an effective biomarker of radionuclide exposure in the natural environment. Combined usage of ecological and molecular biomarkers is advisable for monitoring in rodents from zones of local radionuclide contamination.