Medico-genetic study of the population of Uzbekistan. IV. Medico-genetic description of the population of 4 villages of the Urgut district of the Samarkand region]

The data about the incidence of hereditary diseases and those with genetic predispositions which received after subtotal medico-genetical examination of the inhabitants of 4 villages in the Urgut district of the Samarkand province are presented. 848 inhabitants (348 adults and 464 children aged 7--16 years) are examined. The nosological profile of the morbidity and spectrum of the Mendelian diseases in the population is evaluated. The integrative estimate of load of the detrimental (non-lethal) genes is about 0.166 per individual.     

Medicogenetic study of isolates in Uzbekistan. I. Statement of the problem and characteristics of the groups studied]

The paper comprises results of studying some demographic and populaton characteristics of the inhabitans of the Samarkand region as a whole and two villages, Karakent and Ishan, inhabited with Uzbeks-Khoja, a special religious-social caste in the past. It is shown that 87.4% of marriages in the Samarkand region are of international character (the information has been obtained on 7995 married couples). The frequency of consanguineous marriages is 11.6%, and among them 40.5% are first-cousin marriages and 39.1% are marriages of remote relatives. The coefficients of inbreeding are rather high among the Jewish, Tajik and Uzbek communities. The coefficient of inbreeding as a whole is F=0.0042 in this region and approaches to the maximal level, characterizing a panmix population. The average size of a family in the villages of Karakent and Ishan is approximately 4.0 persons. The values of reproductive performance, the nature of termination of pregnancies do not differ from those of panmix population. The percentage of intravillage and consanguineous marriages are 56% and 12.5% for the first village, and 25% and 2% for the second one respectively. The coefficient of inbreeding for karakent is F=0.0064, for Ishan--F=0.0014. Taking into consideration the historical development of the two villages and the cumulative data, the conclusion is drawn that Karakent is an isolate on a religious ground whereas Ishan is a disintegrated isolate.     

Population genetics of the inhabitants of Northern European USSR. II. Blood group distribution and antropogenetic characteristics in 6 villages in Archangel Oblast]

The paper deals with the distribution of genetic markers (systems ABO, MN, Rh (D), Hp, PTC) and a number of demographic (folding of arms, hand clasping, tongue rolling, right- and left-handedness, of the type of ear lobe, of the types of dermatoglyphic patterns) in the inhabitants of 6 villages in the Mezen District of the Archangelsk Region of the RSFSR (river Peosa basin). The data presented in this work were obtained in the course of examination of over 800 persons. Differences in the interpretation of the results of generally adopted methods of statistical analysis of samples from small populations are discussed. Among the systems analysed in one third of all the cases there was a statistically significant deviation from Hardy-Weinberg's ratios. For the MN blood groups and haptoglobins this was caused by the excess of heterozygotes. The test of Hardy--Weinberg's ratios at the level of two-loci phenotypes revealed no statistically significant deviations either in separate villages or in all the villages taken together. The analysis of heterogeneity with respect to markers inherited according to Mendel's law revealed statistically significant differences between villages in all the systems except haptoglobins. A considerable heterogeneity in the distribution of family names, the frequencies of some of them varying from village to village from 0 to 90%. Statistically significant differences between villages were shown for all the anthropogenetic characters except arm folding, hand clasping and right-left-handedness. Considering the uniformity of the environmental pressure in the region examined, the heterogeneity of the population studied is apparently associated with a random genetic differentiation (genetic drift) and, possibly, with the effect of the progenitor.     

Inbreeding in the Samarkand region]

Data on the frequency of inbreeding in some isolated populations of Samarkand region are given. Statistically significant differences were established in the frequency of inbreeding in separate groups and in the general population of the region. Inbreeding marriages were more observed between paralel cousins, occasionally they were made between secon cousins. Strict time dependence of inbreeding frequency was not found, but it was noticed that the level of inbreeding was reduced since 1930 to 1949.     

Population genetics of the inhabitants of Northern European USSR. I. Data on the structure of 6 villages in Archangel Oblast]

The paper deals with two demographic characteristics of 6 villages in the Archangelsk Region of the RSFSR (river Peosa region) significant from the genetical standpoint. These data were obtained by means of the examination of 843 persons (75,07% of the total number of inhabitants) and of the analysis of complete list of inhabitants permanently living in the villages studied. The proportion of the reproductivity age class was 28.94%, the numbers of men and woman among them being about equal. The average number of children per family in families that have already completed their reproductive period was 3.87, the variance being 4.51 (the data obtained on the basis of examination of over 90 families). The average age of marriage was established to be about 24 years, the duration of each generation being about 32 years. The average index of endogamy per village was observed to be 58.40%, the contribution of the gametes of the preceding generation per village being 72.86%. The migrational influx of gametes from other localities per total of 6 villages was 2.52%. It was shown by the comparison of the character of migrations with mathematical models that the matrix migrational model is the most adequate one.     

Inbreeding and inbreeding depression in a threatened endemic plant,the African violet (Saintpaulia ionantha ssp. grotei), of the East Usambara Mountains,Tanzania

Mating among closely‐related individuals in small and isolated plant populations may result in reduced vigour of the inbred offspring, i.e. inbreeding depression, especially in naturally outbreeding plants. Occurrence of inbreeding and inbreeding depression was studied in Saintpaulia ionantha ssp. grotei, a threatened endemic plant species with a narrow ecological amplitude from the East Usambara Mountains. The level of inbreeding (measured as the fixation index, F) was investigated in twelve populations by analyzing variation at one microsatellite marker locus. The effect of one generation of selfing and outcrossing on the progeny fitness was studied by controlled crosses in two small patches that differ in the level isolation. The fixation index (F) across the populations was on the average 0.21 and varied among the populations from substantial inbreeding (F = 0.58) to surplus heterozygosity (F = −0.29). High inbreeding depression (δ) was observed at early and late stages of the life‐cycle. The isolated patch exhibited lower inbreeding depression than did the non‐isolated patch. The results of this study suggest that inbreeding and subsequent inbreeding depression are potential threats to the survival of Saintpaulia populations.     

Population and demographic study of the Turkmen Tekke

Genetical and demographic studies of typical rural population of Turkomen teke in Yangi-Kala village of the Ashkhabad region (about 5.000 inhabitants) were performed through the examination of a sample of 3528 persons. The population is characterised by intensive growth (mean number of children per one woman is 6.17), a high level of endogamy (the total coefficient of inbreeding being 0.010912), preserving the traditional marriage system (91.9 and 8.1% of intrageneric and intergeneric marriages, respectively). Migration does not significantly influence endogamy, because it takes place among kin families.     

Genetic kinship among an isolated Adi tribe of Arunachal Pradesh: isonymy in the Adi Panggi

Isolated tribes in remote areas are important for genetic studies, and one such little known subtribe of the Adi tribe, namely, the Adi Panggi (Pangi) of the Upper Siang District of Arunachal Pradesh, India, was studied for surname distribution to deduce the deviation from random mating and genetic kinship between villages. The estimates of homonymy (homozygosity) vary between villages; husbands show wider variation (0.009 to 0.23) than wives (0.005 to 0.054). The remote villages of Sumsing and Sibum and Geku Town show lower entropy among husbands' surnames than among Panggi wives. The highest equivalent surname number was found among Sibum husbands (9.9), Panggi wives (12.6), and Panggi and non-Panggi wives (13.5). The estimates of unbiased random isonymy among husbands and wives together show the smallest values in Sibum (0.05) and the highest values in Sumsing and Ramku (0.16). The random and nonrandom components of the inbreeding coefficient show avoidance of inbreeding among the Panggi villages (-0.012 to -0.27) except in Sibum (0.012). Genetic kinship between villages based on the Mij distance shows different clusters of villages among husbands and wives. Both the Panggi wives and the Panggi and non-Panggi wives show a similar pattern of clustering between villages. The wide homonymy variation between villages among the patrilocal Adi Panggi indicates differential genetic kinetics among husbands and wives, avoidance of inbreeding, and female-oriented differential gene flow with little effect on the overall intervillage genetic kinship.     

基于粪便DNA的东北马鹿遗传多样性

东北马鹿(Cervus canadensis xanthopygus)为国家二级重点保护野生动物,近些年其种群数量急剧下降、分布区不断退缩、种群基因交流受阻,很多地区更是难觅其踪迹。亟需对其种群的遗传变化,特别是遗传多样性和近交衰退等种群遗传信息开展进一步评价,增强保护与管理的针对性。本研究在大、小兴安岭和长白山脉的6个重点研究区域,共收集409份疑似马鹿粪便样本。首先基于mtDNA Cyt b基因测序技术进行物种鉴定,并对鉴定为马鹿的阳性样本利用微卫星技术进行个体识别。结果共识别出172只东北马鹿个体;Cyt b基因序列共检测出14个变异位点和11个单倍型,单倍型多样性为0.849 (0.105～0.732),核苷酸多样性为0.678%(0.099%～0.775%)。10个微卫星位点检测出种群平均等位基因数为5.7 (5.2～7.2),有效等位基因数为3.3 (2.5～4.1),观测杂合度为0.687 (0.644～0.725),期望杂合度为0.619 (0.564～0.689),近交系数为-0.113 (-0.160～-0.037)。结果表明,东北马鹿种群遗传多样性处于中等水平,其...     

Long-term exhaustion of the inbreeding load in Drosophila melanogaster

Inbreeding depression, the decline in fitness of inbred individuals, is a ubiquitous phenomenon of great relevance in evolutionary biology and in the fields of animal and plant breeding and conservation. Inbreeding depression is due to the expression of recessive deleterious alleles that are concealed in heterozygous state in noninbred individuals, the so-called inbreeding load. Genetic purging reduces inbreeding depression by removing these alleles when expressed in homozygosis due to inbreeding. It is generally thought that fast inbreeding (such as that generated by full-sib mating lines) removes only highly deleterious recessive alleles, while slow inbreeding can also remove mildly deleterious ones. However, a question remains regarding which proportion of the inbreeding load can be removed by purging under slow inbreeding in moderately large populations. We report results of two long-term slow inbreeding Drosophila experiments (125–234 generations), each using a large population and a number of derived lines with effective sizes about 1000 and 50, respectively. The inbreeding load was virtually exhausted after more than one hundred generations in large populations and between a few tens and over one hundred generations in the lines. This result is not expected from genetic drift alone, and is in agreement with the theoretical purging predictions. Computer simulations suggest that these results are consistent with a model of relatively few deleterious mutations of large homozygous effects and partially recessive gene action.Subject terms: Quantitative trait, Inbreeding     

Population genetics of the population of the northern European RSFSR. III. Demographic and genetic characteristics of two rural communities of the Pinezhskii District of the Arkhangel'sk Region]

The paper deals with the distribution of genetic markers (systems ABO, Rh, Hp, PTC) and a number of phenotyping traits (folding of arms, hand clasping, tongue rolling, right- and left-handedness, the type of ear lobe, the types of dermatoglyphics patterns) in the inhabitants of 5 villages in the Pinezhsky district of the Arkhangelsky region of the RSFSR. The data presented in this work were obtained in the course of examination of over 900 persons. Among the systems analysed there was a statistically significant deviation from Hardy-Weinberg's equlibrium. It took place in two the least villages. In one case--for ABO blood groups, in another--for Hp system. There are an interesting fact of the excess of heterozygotes 2-1 and some excess of the group 0. Statistically significant differences between villages were shown for four genetic systems. Data on migrations, distribution of gene frequencies and estimated genetic and phenotype distances between villages of the same village community and between two communities suggest, that each village community can be considered as separate subdivided population. Considering the uniformity of the environmental pressure in the region examined, the heterogeneity of the population studied is apparently associated with a random genetic drift.     

On the Theory of Partially Inbreeding Finite Populations. I. Partial Selfing

Some stochastic theory is developed for monoecious populations of size N in which there are probabilities beta and 1 - beta of reproduction by selfing and by random mating. It is assumed that beta much greater than N-1. Expressions are derived for the inbreeding coefficient of one random individual and the coefficient of kinship of two random separate individuals at time t. The mean and between-lines variance of the fraction of copies of a locus that are identical in two random separate individuals in an equilibrium population are obtained under the assumption that there is an infinite number of possible alleles. It is found that the theory for random mating populations holds if the effective population number is Ne = N'/(1 + FIS), where FIS is the inbreeding coefficient at equilibrium when N is infinite and N' is the reciprocal of the probability that two gametes contributing to random separate adults come from the same parent. When there is a binomial distribution of successful gametes emanating from each adult, N' = N. An approximation to the probability that an allele A survives if it is originally present in one AA heterozygote is found to be 2(N'/N)(FISS1 + (1 - FIS)S2), where S1 and S2 are the selective advantages of AA and AA in comparison with AA. In the last section it is shown that if there is partial full sib mating and binomial offspring distributions Ne = N/(1 + 3FIS).     

Marriage structure of Yakut populations: Ethnic composition and isonymy inbreeding

Marriage structure has been analyzed in the populations of the administrative centers of five uluses of the Republic of Sakha (Yakutia). The populations studied differ from one another with respect to ethnic composition, namely in the ratio between the indigenous and immigrant populations (the indigenous populations are larger in three uluses), in the proportions of representatives of indigenous ethnic groups among men and women contracting marriages, and in the frequencies of monoethnic and interethnic marriages. Positive assortative marriage among persons of the same ethnic group has been demonstrated. The total inbreeding estimated by isonymy (Fit) varies from 0 to 0.007576.     

薇菜SSR分子标记的开发及遗传多样性初步探讨

利用改良FIASCO法(Fast Isolation by AFLP Sequences COntaining repeats)开发出的9对多态性SSR引物评价了薇菜(Osmunda japonica Thunb.)2个野生居群(庐山和恩施)、1个栽培居群(恩施)的遗传多样性和遗传分化水平。结果显示,9个SSR标记在3个薇菜居群中共检测到47个等位基因,每个SSR位点的平均等位基因数为5.222个,观测杂合度和期望杂合度分别为0.000~0.944和0.577~0.834,香农指数为0.962~1.860,表明各SSR位点多态性较高;各居群的平均期望杂合度均大于平均观测杂合度且种内近交系数均为正值,说明3个薇菜居群中都存在非随机交配现象;对各居群的相关遗传多样性参数分析表明,恩施野生居群遗传多样性最高,而其栽培居群最低;庐山野生居群与恩施野生居群间遗传分化系数为0.092,说明两地野生薇菜居群的遗传分化程度较低,AMOVA分析也表明遗传变异主要存在于野生居群内部。     

Population analysis of minor hemoglobin fractions. I. Hemoglobin A2]

The inhabitants of 7 isolated villages (of different nationalities) and of 5 panmictic populations were studied. Populational and segregation analyses of Hb A2 in 3036 normal and 150 heterozygous individuals for beta- and delta beta-thalassemia were carried out. The Hb A2 levels in some populations are established to deviate from the normal distribution. Bimodal dependency of the levels of Hb A2 distribution is demonstrated, which suggests the existance of heterogenous subpopulations by the Hb A2 level. The segregation analysis has revealed distinct genetic determination of Hb A2 levels. There was a good correlation between Hb A2 and Hb F values (r=-0.82).     

Inbreeding,isonymy, and kin-structured migration in the principality of Andorra

Andorra, one of the smallest countries in Europe, is geographically very isolated. Located in the Central Pyrenees, it is surrounded by high mountains. This paper investigates the endogamous levels and relationships between demographic or geographical variation and inbreeding coefficients calculated through isonymic methods. Our results suggest that political and geographical frontiers are not significant enough to pose effective genetic barriers. The overall inbreeding coefficient average (0.0031) is moderate with respect to other populations in the same region. Temporal and geographical variations of total inbreeding and their components are explained in relation to changes in population size and intensity, and to origin and destination of migrant collectives. Although the spatial distribution of the population of Andorra is the main contributing factor to inbreeding, the kin-structured composition of immigrant collectives is another fundamental factor that helps to explain the levels and variation of inbreeding.     

A comparison of inbreeding rates in India, Japan, Europe and China.

This is a report on an application of a new method for estimating inbreeding rates in large, semi-isolated populations over time. This study is intended to further show the versatility of the method. In a previous study, the method was shown to be useful in analysing the effect of details in a single population curve on inbreeding. In this study, the method is applied to the population curves of India, Japan, Europe and China over the past two millennia, to allow inter-comparisons of the inbreeding within those populations. Anthropologists traditionally concentrate on small isolates within a country for the estimation of inbreeding. Those isolates, however, might not be representative of the country as a whole. The method used in this study attempts to estimate inbreeding over large regions over an extended period of time. The method models the genealogical 'paradox' and yields estimates of the average inbreeding in terms of Pearl's coefficient Z, as a function of time. It is first assumed that the whole population of each country is the adult (breeding) population, corresponding to minimum inbreeding. It is found that the more complex the population curve examined, the greater the precision of the Z curves obtained. The effect of incorporating a single known value of inbreeding into the analyses is also investigated. This procedure produces a more realistic situation where the adult (breeding) population is considerably less than the entire population. It is shown, that if it is assumed that the whole population of the country is the adult (breeding) population, then a present day person from one of the four regions/countries studied is descended from between 72% and 97% of the early medieval population of the particular country. On the other hand, if a known value of inbreeding for Britain is incorporated into the analysis, these values become of the order of 1% for the older-settled regions/countries, and about 16% for Japan. However, that value for Japan is reduced to about 1% when a known value of inbreeding for this country is used. Although some uncertainty in these results remains, the versatility of the method demonstrated here will provide more accurate results, as better input-data become available.     

THE SIGNIFICANCE OF GENETIC EROSION IN THE PROCESS OF EXTINCTION. IV. INBREEDING DEPRESSION AND HETEROSIS EFFECTS CAUSED BY SELFING AND OUTCROSSING IN SCABIOSA COLUMBARIA

The effects of self-fertilization, within-population crosses (WPC) and between-population crosses (BPC) on progeny fitness were investigated in the greenhouse for Scabiosa columbaria populations of varying size. Plants grown from field collected seeds were hand pollinated to produce selfed, WPC, and BPC progeny. The performance of these progenies was examined throughout the entire life cycle. The different pollination treatments did not significantly affect germination, seedling-to-adult survival, flowering percentage and the number of flower heads. But severe inbreeding depression was demonstrated for biomass production, root development, adult survival, and seed set. Additionally, multiplicative fitness functions were calculated to compare relative fitnesses for progeny. On average, WPC progeny showed a more than 4-fold, and BPC progeny an almost 10-fold, advantage over selfed progeny, indicating that S. columbaria is highly susceptible to inbreeding. No clear relationship was found between population size and level of inbreeding depression, suggesting that the genetic load has not yet been reduced substantially in the small populations. A significant positive correlation was found between plant dry weight and total fitness. In two out of six populations, the differences between the effects of the pollination treatments on dry weight increased significantly when seedlings were grown under competitive conditions. This result is interpreted as an enhancement of inbreeding depression under these conditions. It is argued that improvement of the genetic exchange between populations may lower the probability of population extinction.