NONMETRIC VARIATION IN RED VOLE POPULATIONS WITHIN THE EAST-URAL RADIOACTIVE TRACK (EURT) ZONE

Ecological monitoring of red vole Clethrionomys rutilus (Pallas, 1778) populations, carried out for two years (1992-1993) in the Sverdlovsk region near Kamensk-Ural'ski, revealed an increase of morphological di versity in terms of non-metric skull traits along the axis of the East -Ural Radioactive Track (EURT). In the population affected by radioact ive contamination, frequencies of non-metric skull traits deviated sig nificantly from those in two control populations located beyond the EU RT boundaries. The deviations were not related to particular environme ntal factors varying among the years of our study, which implied a gen etic basis of non-metric differentiation. We suggest that the observed increase of phenotypic malformations within the EURT zone has been ca used by the permanent impact of low doses of radioactive contamination , leading to an accumulation of minor mutations and to disturbances in regular ontogenetic development of the red vole.