Genetic demographic description of the Ust-Aldan rural population of Sakha Republic (Yakutia): migrations and marriage structure

Migrations, dynamics of the gametic structure of rural populations, and marriage structure with respect to birthplaces and inbreeding estimated from isonymy have been studied in the Ust-Aldan ulus (administrative district) of Sakha Republic (Yakutia). The villages studied (Byadi, Dyupsya, and Cheriktey) are characterized by intense migration; however, the migration radius is small (most migrations occur within the district). The rural populations studied differ in the intensities and directions of gamete flows and their dynamics. There is no substantial gamete flow into the Ust-Aldan population from outside Sakha Republic. About 50% of marriages contracted in this population are homolocal (between residents of the same district); the endogamy is low (15%). In most cases of heterolocal marriages (contracted between residents of different districts), one of the spouses is a local resident. The inbreeding estimated from isonymy is FTT = 0.002930 in Yakuts; it is mainly accounted for by the nonrandom component (FIS = 0.002232 and FST = 0.000700).     

Genetic Demographic Description of the Ust-Aldan Rural Population of Sakha Republic (Yakutia): Ethnic, Sex, and Age Compositions, Vital Statistics, and Surname Structure

Information on the sex, age, and ethnic compositions; reproductive parameters; intensity of natural selection (Crow's indices); and surname diversity of three rural populations (the Byadi, Dyupsya, and Cheriktey villages) of the Ust-Aldan ulus (district) of Sakha Republic (Yakutia) has been analyzed. The rural Yakut population of the Ust-Aldan ulus is demographically young (the mean age 25–31 years) and characterized by low outbreeding, unfavorable sex ratio in both prereproductive and reproductive ages, and high fertility (3.58–5.45 children surviving until the reproductive age per woman that has completed the reproductive period), although the actual reproductively active period is shorter than half its physiological duration. In the structure of index of total selection, the differential-fertility component is considerably greater than the differential-mortality component (I _tot = 0.625, I _m = 0.093, and I _f = 0.487). In the villages studied, some surnames are accumulated (45–65% of the population have five most frequent surnames), which determines the low surname diversity ( = 11.62–25.19) and high random isonymy (I _r= 0.0391–0.0823).     

Genetic demographic description of the Ust-Aldan rural population of Sakha Republic (Yakutia): ethnic, sex, and age compositions, vital statistics, and surname structure

Information on the sex, age, and ethnic compositions; reproductive parameters; intensity of natural selection (Crow's indices); and surname diversity of three rural populations (the Byadi, Dyupsya, and Cheriktey villages) of the Ust-Aldan ulus (district) of Sakha Republic (Yakutia) has been analyzed. The rural Yakut population of the Ust-Aldan ulus is demographically young (the mean age 25-31 years) and characterized by low outbreeding, unfavorable sex ratio in both prereproductive and reproductive ages, and high fertility (3.58-5.45 children surviving until the reproductive age per woman that has completed the reproductive period), although the actual reproductively active period is shorter than half its physiological duration. In the structure of total selection, the differential-fertility component is considerably greater than the differential-mortality component (Itot = 0.625, Im = 0.093, and If = 0.487). In the villages studied, some surnames are accumulated (45-65% of the population have five most frequent surnames), which determines the low surname diversity (alpha = 11.62-25.19) and high random isonymy (Ir = 0.0391-0.0823).     

Marriage structure of Yakut populations: Migrations

Rural and urban settlements of the Republic of Sakha (Yakutia) are characterized by intense marriage migrations: both indigenous residents of different uluses (districts) of the republic (7–30%) and migrants from outside Yakutia (7–29%) contract marriages in five administrative centers analyzed in this respect. All the populations studied are characterized by a wide geographic range of the birthplaces of persons contracted marriages there (from 14 to 24 uluses of Yakutia), without any predominant migration flow from one district to another. The proportion of homolocal marriages among indigenous ethnic groups (Evenks, Evens, and Yukagirs) is as high as 75–100%; this proportion among Yakuts varies from 26 to 68%; heterolocal marriages are more characteristic of Russian immigrants (41–95%). Positive assortative marriages among persons with the same birthplaces have been found in all populations except for Momsky ulus.     

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.     

Inbreeding and endogamy in Tatarstan

The random inbreeding (F _st) and local inbreeding (a) values have been calculated for populations of the district and rural municipality ranks of 16 and 13 raions (administrative districts) of Tatarstan, Russia, respectively. The correlations between all inbreeding values are positive and vary from 0.38 to 0.80. The endogamy index has been calculated for populations of the district rank; it varies from 0.45 in Pestrechinskii raion to 0.74 in Aktanyshskii raion. Cartographic extrapolation of the endogamy indices has been performed.     

Population genetic structure of the European ground squirrel in the Czech Republic

The European ground squirrel (Spermophilus citellus) is considered an endangered species with declining numbers throughout Europe, most pronounced at the western margin of its distribution area. Being extinct in Germany and Poland, the western margin of its distribution is in the Czech Republic. Here, landscape fragmentation has restricted the ground squirrels into few and very isolated localities where local extinctions still occur. In the present study we analysed European ground squirrels from six Czech and one Slovak localities using five microsatellite loci as genetic marker. The results show a strong genetic differentiation among the investigated populations (mean value of F _ST = 0.16) and high levels of inbreeding (values of F _IS ranged from 0.34 to 0.90). High level of inbreeding is generally considered to affect the viability of each population, which could lead to extinction. One of the most important factors is the lack of migration due to the large distances between the populations and the presence of migration barriers. Based on the results obtained we recommend a few suggestions for a conservation management of this species.     

Population structure of rural settlements of Sakha Republic (Yakutia): Surname structure

The distributions of surnames have been studied in 12 rural ethnic territorial groups of Sakha Republic (Yakutia). The populations studied are characterized by considerable accumulation of individual surnames, the surname spectra of representative of different ethnic groups living in the same area substantially overlapping. The random isonymy, migration index, surname diversity, and the surname distribution redundancy index display geographic and ethnic differences. The isonymy relationship coefficients calculated for representatives of individual ethnic groups (Yakuts, Evens, and Russians) and for total populations of the settlements studied are determined by the geographic distances between the compared populations and the intensity of migrations.     

Population structure of rural settlements of Sakha Republic (Yakutia): surname structure

The distributions of surnames have been studied in 12 rural ethnic territorial groups of Sakha Republic (Yakutia). The populations studied are characterized by considerable accumulation of individual surnames, the surname spectra of representative of different ethnic groups living in the same area substantially overlapping. The random isonymy, migration index, surname diversity, and the surname distribution redundancy index display geographic and ethnic differences. The isonymy relationship coefficients calculated for representatives of individual ethnic groups (Yakuts, Evens, and Russians) and for total populations of the settlements studied are determined by the geographic distances between the compared populations and the intensity of migrations.     

Inbreeding avoidance in an isolated indigenous Zapotec community in the valley of Oaxaca, southern Mexico

We analyzed inbreeding using surname isonymy in an indigenous genetic isolate. The subjects were residents of a rural Zapotec-speaking community in the valley of Oaxaca, southern Mexico. The community can be classified as a genetic isolate with an average gene flow of < or = 3% per generation. Surnames were collected for individuals in each household in pedigree form using the culturally traditional patronym-matronym naming. Estimation of inbreeding from surname isonymy is facilitated by the traditional patronym-matronym name assignment among indigenous Mexican populations. A total of 2,149 individuals had valid surname patronym-matronym pairings, including 484 deceased ancestors. Surname isonymy analysis methods were used to estimate total inbreeding and to segregate it into random and nonrandom components. The surname isonymy coefficient computed from 119 isonymous surname pairings (119/2,149) was 0.0554. The estimated inbreeding coefficient from surname isonymy was 0.0138 (0.0554/4). The random and nonrandom components of inbreeding were F(r) = 0.0221 and F(n) = -0.0091, respectively. The results suggest that consanguinity is culturally avoided. Nonrandom inbreeding decreased total inbreeding by about 41%. Total estimated inbreeding by surname isonymy was 0.0138, which is similar to inbreeding estimated from a sample of pedigrees, 0.01. Socially prescribed inbreeding avoidance substantially lowered total F through negative nonrandom inbreeding. Even in the situation of genetic isolation and small effective population size (N(e)), estimated inbreeding is lower than may have otherwise occurred if inbreeding were only random. However, among the poorest individuals, socially prescribed jural rules for inbreeding avoidance failed to operate. Thus the preponderance of inbreeding appears to occur among the poor, economically disadvantaged in the community.     

Surnames in Siberia: a study of the population of Yakutia through isonymy

We studied the isonymic structure of the Republic of Sakha (Yakutia), in the Russian Federation, using the surname distributions of 491,259 citizens above 18 years registered as residents in 2002. These were distributed in 35 districts and 497 towns and settlements of the Republic. The number of different surnames was 44,625. Matrices of isonymic distances between the 35 districts were tested for correlation with the geographic distance between the population centers of gravity of the districts. We found that, for the whole of Yakutia, Nei's distance was correlated with geographic distance (r = 0.693 +/- 0.027). A dendrogram of the 35 districts was built from the distance matrix, using the UPGMA method. The clusters identified by the dendrogram correlate with the geographic position of the districts. The correlation of random inbreeding calculated from isonymy, F(ST), with latitude was positive and highly significant but weak (r = 0.23). So, inbreeding was highest in the Arctic districts, and lowest in the South. Average alpha for 497 towns was 107, for 35 districts it was 311, and for the Republic 433. The value of alpha was higher for Russian than for the local languages. The geographical distribution of alpha, high in the Center and South-East and lower in the North-West, is compatible with the settlement of groups of migrants moving from the South-East toward the center and the North of Yakutia. It is proposed that low-density demic diffusion of human populations results in high inbreeding and may have been a general phenomenon in the early phases of human radiations.     

Population Genetic Study of the Alatyr' Raion of the Republic of Chuvashia

Population genetic characteristics were estimated in the Alatyr' raion (administrative district) of the Republic of Chuvashia, which has long been populated by three ethnic groups. The ethnic assortativeness values in the town of Alatyr' and the rural area of the district were 1.17 and 1.21, respectively, for Russians; 1.14 and 4.82, respectively, for Chuvashes; and 1.33 and 2.45, respectively, for Mordovians. Wright's statistics were as follows: F _st = 0.00358, F _it = 0.00178, and F _is = 0.00134. The migration indices were 0.0264 for Alatyr' and 0.0178 for the district. The endogamy indices for the total and the Russian populations of Alatyr' were 0.47 and 0.53, respectively. The parameters of isolation by distance were a = 0.000189 and b = 0.009591 for the urban and a = 0.000318 and b = 0.00919 for the rural area. Schemes of the genetic landscape were constructed. The influence of the polyethnic composition on the genetic structure of the population is discussed.     

Inbreeding among endogamous groups in three multicaste villages of Srikakulam district,Andhra Pradesh,India

Abstract

In the present paper 702 families have been studied belonging to different endogamous groups in three multicaste villages of Srikakulam District, Andhra Pradesh. It is observed that 33.76 per cent of families are consanguineous marriages. With regard to the types of marriages, 12.11 per cent are uncle‐niece; 14.10 per cent are matrilateral cross‐cousins; 5.84 per cent are patrilateral cross‐cousins; 0.57 per cent are first cousins once removed, and 1.14 per cent are second cousins. There are only six couples (0.86 per cent) in intercaste marriages. The coefficient of inbreeding for autosomal and sex‐linked genes, 0.045 and 0.059, respectively, for Chakalis which are higher than Kalingas (F = 0.03; F1 = 0.038), Segidis (F = 0.031; F1 = 0.041), Velamas (F = 0.026; F1 = 0.036), Vysyas (F = 0.027; F1 = 0.034), Malas (F = 0.017; F1 = 0.026), and others (F = 0.026; F1 = 0.032). The t‐tests for mean marriage distances are statistically significant among all castes, but chi‐squares for intergroup difference of consanguineous and nonconsanguineous marriages are statistically significant only among Kalingas and Chakalis, Vysyas and Chakalis, and Malas and Chakalis.     

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.     

Interspecific Genetic Variability of the Oyster Mushroom Pleurotus ostreatusAs Revealed by Allozyme Gene Analysis

Allozyme variation in natural populations of basidiomycete fungus Pleurotus ostreatus (88 individuals) from three regions of central Russia was studied. The species was shown to have 92.86% of polymorphic allozyme loci and expected heterozygosity H _e = 0.49. The mean number of alleles per locus was 3.5. The genetic differences among populations were supported by F-statistics (F _ST = 0.750). The low level of inbreeding (F _IS = 0.018) suggests that the P. ostreatus populations are panmictic, and the main reproduction mode involves basidiospores dispersing at long distances. Using cluster analysis, geographically isolated populations and intersterile groups were differentiated within the complex P. ostreatus species.     

Allelic polymorphism of six microsatellite DNA Loci in populations of Sakha (Yakutia)

The allele frequency distributions of six STR loci (D3S1358, D16S539, THOI, D8S1179, LPL, and HUMvWFII) used in forensic practice were analyzed in populations of Sakha (Yakutia): three ethnogeographical groups of Sakha (Yakuts), Evenks, Yukagirs, Dolgans, and Russians. There were significant differences between Russians and all other populations by five markers. The total discriminating power (PD) of the locus system studied was assessed for each population. The interpopulation genetic difference (F _ST) was 0.005. Data on the allelic polymorphism of the above STR loci were used to analyze phylogenetic relationships among the populations of Sakha and those of other regions: East Europe, South Siberia, Chukotka, and Kamchatka.     

Patterned selection of mates in St. Ouen, Jersey, and the Scilly Isles examined by isonymy

Within-lineage repeated-pair isonymy is calculated as RPW = sigma [Sij(Sij - 1)]/sigma [Si(Si - 1)], in which Sij is the number of a combination of two surnames in marriages (for total RPW, in both orders, brides first and also grooms first) and Si is the corresponding number of individuals of each surname (for total RPW of both sexes). In St. Ouen the 3479 native Jersey marriages between 1634 and 1914 yield a mean total RPW of 0.03314, which can be compared with a random isonymy (Ir) of 0.02205 and a marital isonymy (Im) of 0.04942. In the most recent time periods (1830-1914) there was an increase in RPW, but the increase is small if all marriages are considered rather than only native Jersey ones. In the Scilly Isles 2827 marriages between 1725 and 1975 yield a mean total RPW of 0.05127, which compares with a mean Ir of 0.01960 and an Im of 0.05238. In each kind of isonymy there is a decline over 1850-1975 caused by increased migration to the Scilly Isles. In the Scilly Isles RPW consistently approximately equals Im, so the nonrandom component of inbreeding is fully accounted for by factors that affect marital choice in the whole lineage. In St. Ouen, however, RPW is intermediate in value between Ir and Im, so the nonrandom component of inbreeding is only partly a lineage phenomenon and is also affected by other (individual) factors in choice of spouses.     

Genetic and demographic characteristics of rural populations of Altaĭ republic: dynamics of the marriage structure

The dynamics of population marriage structure in the period from 1951 to 1997 has been studied in three villages of Altai Republic: Kulada (Ongudaisk raion), Beshpeltir (Chemal raion), and Kurmach-Baigol (Turochak raion). These populations have been found to differ from one another in the intensity and direction of migration, as well a its temporal pattern with respect to the birthplaces and ethnicity of persons contracting marriages. Periods of active incorporation of non-Altaian (mostly Slavic) ethnic components into the gene pools of the Beshpeltir and Kurmach-Baigol populations have been detected. The geographic distributions of the birthplaces of men and women contracting marriages are different. Therefore, migration has different effects on the genetic diversity of the Y-chromosomal and mitochondrial-DNA pools. No isonymic marriages have been found in the Altaian populations studied; however, an increase in the random component of inbreeding has been observed.     

DO BLACK-TAILED PRAIRIE DOGS MINIMIZE INBREEDING?

Considerable controversy surrounds the importance of inbreeding in natural populations. The rate of natural inbreeding and the influences of behavioral mechanisms that serve to promote or minimize inbreeding (e.g., philopatry vs. dispersal) are poorly understood. We studied inbreeding and social structuring of a population of black-tailed prairie dogs (Cynomys ludovicianus) to assess the influence of dispersal and mating behavior on patterns of genetic variation. We examined 15 years of data on prairie dogs, including survival and reproduction, social behavior, pedigrees, and allozyme alleles. Pedigrees revealed mean inbreeding coefficients (F) of 1–2%. A breeding-group model that incorporated details of prairie dog behavior and demography was used to estimate values of fixation indices (F-statistics). Model predictions were consistent with the minimization of inbreeding within breeding groups (“coteries,” asymptotic F_IL = –0.18) and random mating within the subpopulation (“colony,” asymptotic F_IS = 0.00). Estimates from pedigrees (mean F_IL = –0.23, mean F_IS = 0.00) and allozyme data (mean F_IL = –0.21, mean F_IS = –0.01) were consistent with predictions of the model. The breeding-group model, pedigrees, and allozyme data showed remarkably congruent results, and indicated strong genetic structuring within the colony (F_LS = 0.16, 0.19, and 0.17, respectively). We concluded that although inbreeding occurred in the colony, the rate of inbreeding was strongly minimized at the level of breeding groups, but not at the subpopulation level. The behavioral mechanisms most important to the minimization of inbreeding appeared to be patterns of male-biased dispersal of both subadults and adults, associated with strong philopatry of females. Incest avoidance also occurred, associated with recognition of close kin via direct social learning within the breeding groups.     

Analysis of Marital Migrations in Two Ouluses of the Republic of Sakha (Yakutia)

The marital migration structure of two ouluses (administrative districts) of the Republic of Sakha (Yakutia) that have long been populated by three ethnic groups were studied on the basis of marriage records. Population genetic characteristics were calculated for each ethnic group. The ethnic assortativeness values were 30.9 in Evens, 1.36 and 4.46 in Russians, and 1.03 and 4.51 in Yakuts. The endogamy indices for the oulus and republican ethnic populations, respectively, were 0.83 and 1.0 in Evens, 0.41 and 0.99 in Yakuts, and 0.08 and 0.14 in Russians. The parameters of isolation by distance were the following: a = 0.0013 and b = 0.0020 in the Gornyi oulus; a= 0.0048 and b = 0.0014 in the Krest-Khaldzhai rural municipality;a = 0.0086 and b = 0.0095 in the Topolinoe rural municipality; anda= 0.0106 and b= 0.0013 in the Megino-Aldan rural municipality.