[Significance of indices of potential selection for residents of the USSR].

Crow's indices of the opportunity for selection and their components connected with differential mortality (Im) and differential fertility (If) were estimated for populations of Soviet Union republics and for a number of USSR ethnic groups on the basis of demographic statistics. More than 10-fold decrease in the Im value was revealed in the total population of the USSR during 1926-1987. At present, the Im values in republics vary from 0.020 to 0.094 for urban population and from 0.030 to 0.121 in rural population, the ratio of perinatal mortality in the whole structure of prereproductive mortality being higher in the republics with lower values of the Im. The range of the If values for different peoples (0.148-0.643) is wider than for the populations of the republics (0.326-0.578). Interethnic differences contribute 47% of the variance in fertility. The structure of Crow's indices is given for urban and rural populations of the republics. Genetic implications of the data presented are discussed with respect to possible manifestation of the effects of inter-group selection.