A GENETIC DEMOGRAPHIC-STUDY OF DAGESTAN H IGHLAND POPULATIONS AND MIGRANTS FROM THEM TO LOWLANDS - COMPARISON OF THE MAIN INDICATORS OF FITNESS

Results of a total genetic demography study of females of postreproduc tive age from both parts of ''split'' highland isolates of Dagestan, h ighlanders, and migrants to lowlands are described. The components of natural selection that were related to differential mortality and diff erential fertility were estimated in the highlanders and the migrants using Crow indices. Offsprings of female migrants were characterized b y a higher prenatal (spontaneous abortions and still-births) and a low er prereproductive mortality. These differences may be accounted for b y two mechanisms: (1) the effects of changing marital structure (femal e migrants are more exogamous) and (2) better medical care for the chi ldren of migrants compared to those living in highland auls (settlemen ts), which are still difficult to access. It was demonstrated that mor tality of probands' children before reproductive age, as well as the p roportion of their close genetic relatives that died within five years after resettling, increased with an increase in the level of individu al inbreeding in women examined (probands). These data allow us to sug gest that the drastic increase revealed in mortality of the highlander s during the first years after resettling may be partially attributed to high levels of inbreeding and heterozygosity; these, in turn, decre ase the individual's nonspecific resistance to new ecological factors. Fertility and prenatal mortality appeared to increase and decrease, r espectively, with an increase in the inbreeding level.