[Variation of the allele composition and protein locus expression in the course of genetic differentiation of taxa of various ranks in mammals].

The contributions of different groups ofloci, namely those identical (i), similar (s), and different (d) with respect to allele composition and the loci expressed in only one of two compared objects (O), into the differentiation of marsupial and placental mammals have been evaluated. An increase in the proportions of d and 0) loci with increasing taxon rank has been demonstrated. At the intraspecific level, identical loci are prevailing, and d loci are rare; the latter are more common in subspecies. At the species level, the proportions of different (d) and similar (s) loci are increased, but the proportion of i loci is still the highest. Only at the genus level does the proportion of different loci reach 41-49%; 0 loci are found in marsupials and small placental mammals, and the number of s loci is decreased. In large placental mammals, this trend is disrupted at the subspecies level, where the contribution of s loci is drastically increased, while the proportion of identical ones (i) is decreased. Comparison with data on other groups of vertebrates shows that the ratios between these groups of loci reflect the specificity of differentiation processes at the intraspecific level and the levels of species and taxa of higher ranks in all classes of animal analyzed. However, the species differentiation in amphibians approximately corresponds to the genus level in mammals and the family level in birds.