Species-Specific Features of Inter- and Intrapopulation Variation in the Level of Chromosome Instability in Rodents

Studies on the common vole Microtus arvalis revealed a distinct cytogenetic response to the influence of ionizing radiation, a wide range of variation in the group average indices of chromosome instability beyond the zone of technogenic impact, and the influence of natural factors (viral infections and fluctuations of population size) on the frequency of chromosome aberrations. In the northern mole vole Ellobius talpinus, neither the mutagenic effect of ionizing radiation nor interpopulation differences in the level of chromosome aberrations in the absence of anthropogenic impact were detected. Variation of genome instability of the rodents is significantly contributed to by species demography and population cycles.     

Genomic instability in the bank vole: Population-ecological aspects

Chromosome aberration frequency in relation to population dynamics and demographic parameters was studied for six years in a bank vole population in the Middle Urals. The frequencies of structural chromosome aberrations, chromatid gaps, aneuploidy, and polyploidy in males and females and in animals of different ages did not differ significantly. In the breeding period, the frequencies of structural aberrations and changes in chromosome number increased in the somatic cells of voles. Highly significant differences between the levels of chromosome instability in different years manifested a tendency toward a negative correlation with population size.     

Fluctuating Asymmetry in Cranial Measurements of East European Voles (Microtus rossiaemeridionalis Ognev, 1924) from the Zone of Radioactive Contamination

Fluctuating asymmetry (FA) in eight cranial measurements was studied in Microtus rossiaemeridionalis voles from two sites of the zone affected by the Totsk Radioactive Trace (TRT) and in the control population. In the affected populations, generalized mean population parameters of FA were significantly higher than in the control and tended to increase in relatively larger animals. The disturbance of ontogenetic homeostasis in voles from the TRT zone probably resulted from environmental stress caused by contamination with radionuclides (primarily plutonium), which entailed irradiation of many vole generations over more than 40 years.