[Genetic-demographic study of mountain populations from Dagestan and their migrants to the lowlands. Comparison of basic parameters of fitness].

Results of a total genetic demography study of females of postreproductive age from both parts of "splits" highland isolates of Dagestan, highlanders, and migrants to lowlands are described. The components of natural selection that were related to differential mortality and differential fertility were estimated in the highlanders and the migrants using Crow indices. Offsprings of female migrants were characterized by a higher prenatal (spontaneous abortions and still-births) and a lower prereproductive mortality. These differences may be accounted for by two mechanisms: (1) the effects of changing marital structure (female migrants are more exogamous) and (2) better medical care for the children of migrants compared to those living in highland auls (settlements), which are still difficult to access. It was demonstrated that mortality of probands' children before reproductive age, as well as the proportion of their close genetic relatives that died within five years after resettling, increased with an increase in the level of individual inbreeding in women examined (probands). These data allow us to suggest that the drastic increase revealed in mortality of the highlanders during the first years after resettling may be partially attributed to high levels of inbreeding and heterozygosity; these, in turn, decrease the individual's nonspecific resistance to new ecological factors. Fertility and prenatal mortality appeared to increase and decrease, respectively, with an increase in the inbreeding level.