A COMPARATIVE-STUDY OF GENETIC ADAPTATION S TO THE HISTORICAL AND NEWURBAN ENVIRONMENTS IN CAUCASIAN HIGHLANDERS

Marriage structure and female reproductive characteristics in a highla nd isolate and an urban population from Daghestan were compared. The s tudied urban population could be divided into three groups according t o ethnic, genetic, and demographic parameters. In the native, highland population, a steady selection occurred due to a high, uncontrolled b irthrate and a high prereproductive mortality. The genetic structure o f the urban population still remained at the stage of formation. Diffe rent 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 trad itional endogamous and inbred marriage structure exhibited a high infa nt mortality comparable to that in the highland population. The migran t subpopulation in which interpopulation and interethnic marriages wer e contracted exhibited an increased genetic load expressed as high pre -and perinatal mortalities. The results obtained are discussed in term s of the hypotheses on the adaptive gene complex and the genetic and p hysiological mechanisms of differential adaptation of highland isolate s to environmental changes due to migration or environmental pollution .