[A genetic and demographic study of Dagestan highland populations and migrants to the lowlands. The relationship between levels of consanguinity, homozygosity and physiologic sensitivity]. / Genetiko-demograficheskoe issledovanie gorskikh populiatsii Dagestana i migrantov iz nikh na ravninu. Vzaimosviaz' urovnei inbridinga, homozigotnosti i fiziologicheskoi sensitivnosti.

This is a continuation of a series of papers devoted to studying the genetic mechanisms of adaptation in migrants from isolated highland populations of Dagestan to new ecological conditions (lowlands). This paper describes the main results of studying the relationship between levels of inbreeding, homozygosity, and physiological sensitivity. Earlier, we found that decreased resistance to changing environmental factors in migrants to lowlands from the Dagestan highlands was connected with their high level of homozygosity. The data obtained allow us to assume that missing links in this chain of events include, in addition to parameters of inbreeding level, parameters of neurophysiological sensitivity, including absolute and differential sensitivity of various analyzers sensory systems, which are from 65 to 75% genetically determined. Migrants from highland auls (villages) to lowlands exhibited a decreased rate of sensomotor reactions in response to light and sound of various intensities, as well as decreased differential color sensitivity in the long-, medium-, and short-wave ranges of the spectrum, compared to highlanders. The results suggest the selective mortality of migrants from highlands to lowlands during adaptation to new conditions. Those migrants who dies were characterized by specific gene complexes that determined the characteristic features of expression of a number of interrelated polymorphic and quantitative traits. Thus, the high levels of homozygosity and inbreeding were accompanied by a greater neurophysiological sensitivity and lower indices of body weight and height.

[Genetic-demographic study of mountain populations from Dagestan and their migrants to the lowlands. Comparison of basic parameters of fitness]. / Genetiko-demograficheskoe issledovanie gorskikh populiatsii Dagestana i migrantov iz nikh na ravninu. Sravnenie osnovnykh prarametrov prisposoblennosti.

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.

[Genetic-demographic study of mountain populations of Daghestan and migrants from it to the lowlands. Study of genetic and marital structure]. / Genetiko-demograficheskoe issledovanie gorskikh populiatsii Dagestana i migrantov iz nikh na ravninu. Izuchenie geneticheskoi i brachnoi struktury.

The results of a genetic and demographic study of two "split" isolates of small native ethnic groups of Daghestan are described. Parts of these populations were resettled from habitual highland ecological conditions to radically new lowland conditions in the 1940s. These split isolates were compared with a population of native inhabitants of the Daghestan lowland. It was found that, since resettling, separated populations originating from split isolates became significantly different in both marriage and genetic structures. This is manifested in different phenotypic and allelic frequencies of a number of physiological and biochemical markers and in levels of their heterozygosity. To explain the differences revealed, a hypothesis was proposed about the relationship between levels of inbreeding, heterozygosity, and physiologic sensitivity that account for the differential adaptability of members of the isolated populations to changing environmental conditions. This is the first report of a series of papers describing the experimental testing of this hypothesis. While testing the validity of the hypothesis in this study, a positive linear correlation was found between inbreeding and homozygosity levels.