Population genetic study of Russian cosmonauts and test subjects: genetic demographic parameters and immunogenetic markers

Genetic demographic characteristics and immunogenetic markers (blood groups ABO, Rhesus, MNSs, P, Duffy, Kidd, and Kell) have been studied in a group of 132 Russian cosmonauts and test subjects (CTSG). Analysis of pedigrees has shown a high exogamy in the preceding generations: almost half of the subjects have mixed ethnic background. According to the results of genetic demographic analysis, a sample from the Moscow population was used as control group (CG). Comparison between the CTSG and CG has demonstrated significant differences in genotype frequencies for several blood group systems. The CTSG is characterized by a decreased proportion of rare interlocus genotypic combinations and an increased man heterozygosity. Analysis of the distributions of individual heterozygosity for loci with codominant expression of alleles has shown that highly heterozygous loci are more frequent in the CTSG. Taking into account that the CTSG has been thoroughly selected from the general population, it is concluded that heterozygosity is related to successful adaptation to a space flight.     

Role of migration processes in shaping the marriage structure of the Moscow population. I. The age, place of birth and nationality of those entering marriage

A genetic-demographic study of the dynamics of the Moscow population marriage structure, with respect to the age of marriage, birthplace and nationality of newlyweds has been carried out by means of sample analysis of 1955 and 1980 marriage records; some other demographic and statistic data obtained during several years were also used. The mean age of marriage being practically constant, the proportion of newlyweds younger than 20 in the reproductive part of the Moscow population was shown to be considerably higher at the beginning of the XX century than at present. The number of couples married at the postreproductive age increased in 1980, as compared with 1955. The process of migration contributing to the genetic structure of subsequent Moscow generations has been characterized quantitatively and from the spatio-geographical point of view. High values (0.57 less than m less than 0.86) of the coefficient of migration to Moscow correspond to the period of non-controlled city population growth. As a result of administrative measures for regulation of the city population growth, the value of the coefficient of migration to Moscow decreased considerably by 1980, though still remained at a rather high level (m=0.40). The mean migration distance increased from 230 km, in the beginning of XIX century to 560 km in 1955 and 1100 in 1980. Especially great was the increase of genetic contribution from Eastern and Southern regions of the USSR. The variability of the national composition also increased. These changes in the geography of migration will cause the increasing reproduction of the entire country gene pool in Moscow as a panmixia center that may result in genetic originality of the Moscow population.     

Strategies of adaptation: interpopulation selection differentials

Spatial and temporal variation of selection intensities has been analyzed using published data on Crow's indices in 278 human populations, representing various anthropological types, religions, cultures and a wide spectrum of environmental conditions. Statistical analysis has shown that populations with different types of economy have different adaptive strategies. In tribal populations both components of selection-differential fertility and differential mortality-have equal contributions, vary according to ecological factors and show no decline with time. Urban populations of the industrially developed countries show dramatic selection relaxation; the second component becomes negligible due to a sharp decrease in childhood mortality; fertility and its variance are reducing due to cultural factors (family planning).     

The role of migration processes in the formation of marriage structure of Moscow population. II. Assortative mating for the age, birthplace and nationality

Positive assortative mating for age at marriage, birthplace and nationality has been revealed by means of sample analysis of couples married in Moscow in 1955 and 1980. The correlation coefficient between mates for age at marriage was r = 0.81 in 1955 and r = 0.88 in 1980; the age difference between spouses had a mean of 1.55 and 2.21 years, respectively. The determinative role of migration in forming Moscow population marriage structure accounts for the fact that the greater part of marriages registered in the capital are between migrants from various regions of the USSR or between the Moscow-born and the migrants. The proportion of marriages between individuals born in Moscow has increased over 25 years from 10 to 38%, these values being significantly higher than those expected under random mating between the migrants and the Moscow-born. The contingency coefficient measuring the association between the birthplaces of husband and wife was K = 0.16 in 1955 and K = 0.11 in 1980, the preferential marriage between mates born in the same region being still significant even when marriages are registered in Moscow. The highest degrees of assortative mating were observed for nationality character: K = 0.37 in 1955 and K = 0.28 in 1980. The decrease in these values over the past 25 years has resulted in a slight growth of the proportion of international marriages (from 14.75 to 16.53%) which has not yet reached the level expected under panmixia (about 21%).     

Genetic demography of populations of three megalopolises in relation to the problem of creating genetic databases

Based on data collected from urban residents by questionnaire, the basic parameters of the genetic-demographic structure of populations of the three megalopolises, i.e., Moscow, Kharkov, and Minsk, have been calculated, including the migration coefficients and their dynamics in generations, the radius of the cities migration attraction, the parameters of marriage structure (the proportion of interethnic marriages, the level of intraethnic assortative mating the marital distances), and the gene flow between the ethnic groups. Representatives of the most numerous ethnic group of each megalopolis show significant amount of admixture. For Russians of Moscow, Ukrainians of Kharkov, and Belarusians of Minsk, the proportion of individuals whose ancestors were all born in the given city for at least three generations and belonged to the same nationality turned out to be very low (4.75% in Moscow, 1.83% in Kharkov, and 3.13% in Minsk). This finding questions the formation of a reference population in the megalopolis as a sampling of aboriginals of certain ethnic origins. In the paper, we justify principles of creating genetic databases for the population of the megalopolis taking into account the complexity and dynamism of its population structure.     

Variation of the parameters of natural reproduction and Crow’s indices in the ethnic groups of Dagestan

Using the 2002 All-Russian population census data, the parameters of differential fertility as a component of natural selection (Crow??s indices) have been calculated for women of seven age cohorts of the seven most numerous ethnic groups of the Republic of Dagestan. It has been shown that in the population of Dagestan in the second half of the 20th century the intensities of two types of selection tended to decrease, viz., intragroup selection relaxed in each ethnic group due to considerable reduction of interfamily variance in fertility and intergroup selection relaxed due to reduction of interethnic differences in fertility. A reduction of the average number of offspring (k) was observed in all ethnic groups, suggesting the spread of birth regulation practices (abortion and contraception). Nevertheless, all Muslim groups (aboriginal Dagestan ethnic groups and Azerbaijanis) are still characterized by an extended pattern of reproduction (2.7 < k < 3.3); in Russians k = 2.1. Interethnic differentials in natural reproduction rates, along with migration processes, account for the dynamics of the ethnic composition and gene-pool structure of the population of the Republic of Dagestan.     

Variation of natural reproduction parameters and Crow’s indices in different ethnic groups in the two largest megacities of Russia

Genetic-demographic parameters of natural reproduction in the most numerous ethnic groups of Moscow and St. Petersburg were assessed on the basis of the 2002 All-Russia Population Census data and other sources. The intensity of intragroup selection due to individual differences in fertility in the cohorts of women born in the 1930s–1950s decreased in all ethnic groups studied. It was concluded that, in both megacities, the relaxation of the selection component due to differential fertility almost stopped: the values of the Crow’s index I_f stabilized at 0.3 < I_f < 0.4, which was associated with relative stabilization of the interfamily variance of fertility. The temporal dynamics of the intensity of intergroup selection due to interethnic differences in fertility rates was more complex. It was only recently that this type of selection came into action, since even at the beginning of the 20th century fertility rates in various ethno-territorial and ethno-confessional groups of the population of the Russian Empire were similar (5–6 offspring per marriage). In the subsequent decades, interethnic differentiation in progeny size increased because the reproductive behavior of different population groups underwent “modernization” with uneven speed. In Moscow and St. Petersburg, the intensity of intergroup selection decreased in women birth cohorts of the 1930s–1950s, while it was an order of magnitude lower than the intragroup selection. Currently, the average number of offspring varies among ethnic groups in a narrow range from 1.3 to 1.6. It can be expected that interethnic differences in fertility rates in these megacities will increase again owing to growing numbers of migrants from regions with traditionally high birth rates, resulting in differential natural growth of ethnic groups and the corresponding dynamics of the gene pool of the population.     

Territorial Subdivision of the Megalopolis Population by the Ethnic Trait in Relation to the Problem of Creating Genetic Databases. St. Petersburg

Russian Journal of Genetics - On the basis of the materials of the 2010 All-Russia Population Census in St. Petersburg, an analysis of uneven settlement of ethnic groups over the city districts was...     

Genetic Demography of the Population of St. Petersburg: Migration Processes

Russian Journal of Genetics - The principal genetic demographic parameters that describe migration processes affecting the structure of the St. Petersburg population gene pool were determined on...