[Comparative study of genetic adaptation of the Caucasian highlanders to historic and to the new urban environments].

Marriage structure and female reproductive characteristics in a highland isolate and an urban population from Dagestan were compared. The studied urban population could be divided into three groups according to ethnic, genetic, and demographic parameters. In the native, highland population, a steady selection occurred due to a high, uncontrolled birthrate and a high prereproductive mortality. The genetic structure of the urban population still remained at the stage of formation. Different ethnic groups of the female urban population differed both in the rate and directions of selection. The migration of highlanders to the city mainly affected their mortality and morbidity, but not fecundity. The subpopulation of migrants from the highlands who retained a traditional endogamous and inbred marriage structure exhibited a high infant mortality comparable to that in the highland population. The migrant subpopulation in which interpopulation and interethnic marriages were contracted exhibited an increased genetic load expressed as high pre- and perinatal mortalities. The results obtained are discussed in terms of the hypotheses on the adaptive gene complex and the genetic and physiological mechanisms of differential adaptation of highland isolates to environmental changes due to migration or environmental pollution.