The population structure of rural settlements of Sakha Republic (Yakutia): migration

Migration and gametic structure have been analyzed in rural population of Sakha Republic (Yakutia). The populations studied differ from one another in the migration rate and direction, which are determined by the socioeconomic development of the regions and ethnic composition of settlements. A high rate of long-distance migrations and a low rate of migrations within uluses (districts) are characteristic of regions with well-developed industry and transportation and are more characteristic of immigrant than indigenous populations. In rural regions, migrations within uluses are more prevalent. The gametic structure of the youngest age group does not always correspond to the migration activity of previous generations. The migration effectiveness values (the correspondence of migration flows to the gametic structure depending on the geographic origin of the gametes) are different for men and women.     

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.     

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).     

Migration rates as inferred from the 2002 Russian census

Migration rates in the modern Russian population have been studied on the basis of the results of the 2002 census. The migration rate at the population level corresponding to a city or rural administrative district is m = 0.443. The migration rate for women (m(F) = 0.463) is 11% higher than for men (m(M) = 0.418); the migration rate for urban populations (m(U) = 0.459) is 15% higher than for rural populations (m(R) = 0.398). The geographic variation of migrations has been studied; the geographic distributions of the migration rates for rural, urban, male, and female populations are presented. Comparison of migrations in the rural population of Russia at two temporal cross-sections (1970 and 2002) has shown that the geographic structure of migrations has remained the same in many respects. The ecological factor has remained the main determinant of the migration geography, which is expressed in the relationship of the settled way of life with the forest-steppe and broad-leaved forest landscapes.     

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 F _IT = 0.002930 in Yakuts; it is mainly accounted for by the nonrandom component (F _IS = 0.002232 and F _ST = 0.000700).     

Genetic demographic structure of rural populations of Kyrgyzstan

The genetic demographic parameters of rural populations of Kyrgyzstan have been studied. The rural population of Kyrgyzstan has the following demographic characteristics: (1) it is demographically young (the population mean age is 25-28 years); (2) the sex ratio in reproductive age groups is unfavorable; (3) the fertility is high (5.78-7.68 pregnancies and 4.27-5.20 surviving children per woman of postreproductive age; (4) interethnic marriages are rare (1.0-5.9%), whereas consanguineous marriages are frequent (1.4-12%); (5) Crow's indices are relatively low (I(tot) = 0.24-0.29, I(m) = 0.05-0.13, I(f) = 0.14-0.22); and (6) both male and female contributions of different regions of the republic make unequal contributions to the gametic structure of the population, with the gametic structure varying from generation to generation. Demographic parameters vary in rural populations of different geographic regions and with different ethnic compositions.     

Geography of genetic processes in the population: genetic migration in Northern Eurasia (Central Asia region)]

Based on the data of the census of 1970, a map of the rates of gene migrations in the rural population of Central Asia and Kazakhstan was drawn. The corrected average value for 35 populations of oblasts (administrative regions) and autonomous republics was m = 0.0606 +/- 0.0102. The estimate obtained from the mapped data was 0.0799 +/- 0.0014, which is 1.2-fold higher than similar values for Europe. The relationship between the rate of gene migration m, the genetically effective population size Ne, and the density of elementary populations in the studied area Pp was analyzed by means of correlation and regression analyses. The following relationship was obtained: m = A/Ne + BPp, where A > 0 and B < 0. This was accounted for by the fact that the migration flow is mainly directed to the less densely populated rural areas. Given that the region was chosen somewhat artificially, studying gene migrations in Central Asia and Kazakhstan as separate historical, geographic, and genetic subregions of northern Eurasia might be a better approach.     

The population structure of rural settlements of Sakha Republic (Yakutia): Ethnic, sex, and age composition and vital statistics

The genetic demographic structure of 12 rural populations from eight uluses of Sakha Republic (Yakutia) has been analyzed. The ethnic, sex, and age composition of the population and the reproductive parameters of women that have completed and have not completed the reproductive period are reported. Crow’s indices have been estimated in representatives of three indigenous ethnic groups (Yakuts, Evens, and Evenks).     

The population structure of rural settlements of Sakha Republic (Yakutia): ethnic, sex, and age composition and vital statistics

The genetic demographic structure of 12 rural populations from eight uluses of Sakha Republic (Yakutia) has been analyzed. The ethnic, sex, and age composition of the population and the reproductive parameters of women that have completed and have not completed the reproductive period are reported. Crow's indices have been estimated in representatives of three indigenous ethnic groups (Yakuts, Evens, and Evenks).     

Genetic Demographic Structure of Rural Populations of Kyrgyzstan

The genetic demographic parameters of rural populations of Kyrgyzstan have been studied. The rural population of Kyrgyzstan has the following demographic characteristics: (1) it is demographically young (the population mean age is 25–28 years); (2) the sex ratio in reproductive age groups is unfavorable; (3) the fertility is high (5.78–7.68 pregnancies and 4.27–5.20 surviving children per woman of postreproductive age; (4) interethnic marriages are rare (1.0–5.9%), whereas consanguineous marriages are frequent (1.4–12%); (5) Crow's indices are relatively low (I _tot = 0.24–0.29, I _m = 0.05–0.13, I _f = 0.14–0.22); and (6) both male and female contributions of different regions of the republic make unequal contributions to the gametic structure of the population, with the gametic structure varying from generation to generation. Demographic parameters vary in rural populations of different geographic regions and with different ethnic compositions.     

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.     

Simulation of the distribution of spinocerebellar ataxia type 1 in Yakut populations: Model parameters and results of simulation

Demographic and clinical genetic parameters used for simulation modeling of the prevalence of spinocerebellar ataxia type 1 (SCA1) in Yakut populations are described. Demographic parameters of simulated populations and the clinical genetic characteristics of carriers of the SCA1 mutant allele in them have been compared with actual data on Abyisky and Ust-Aldansky uluses of the Republic of Sakha (Yakutia). The results of a series of simulation experiments (without migration or spontaneous mutagenesis) agree with the conclusion that the high prevalence of rate of spinocerebellar ataxia type 1 in Yakut populations may be maintained because of their specific demographic structure. Prediction of the disease prevalence has shown that it will take about 1290 years for natural selection to eliminate the mutation from the population. If medical genetic counseling (MGC) is offered to 1% of the carriers of the mutation, this period will be reduced to 200 years.     

Selective sweeps and intercontinental migration in the cosmopolitan moss Ceratodon purpureus (Hedw.) Brid

The moss Ceratodon purpureus has long been used as a model system in plant development and physiology. However, the molecular population genetics of the species remains virtually unexplored. In this study, we used population genetic analyses of DNA sequence data from three unlinked loci (atpB-rbcL spacer, adk, and phy2) to examine biogeographical patterns in a global sample of this species. The three loci differed significantly in mutation frequency spectra and implied population structure. Pairs of haplotypes from single populations were frequently more divergent than haplotypes sampled from widely disjunct populations. In the atpB-rbcL spacer and adk samples, Australasian haplotypes were more closely related to Northern Hemisphere haplotypes than to haplotypes found in the equatorial regions. In contrast, the phy2 sample showed that the north and south temperate regions were genetically divergent, with the equatorial regions intermediate. Maximum-likelihood estimates (MLE) of the rates of migration between the two hemispheres were significantly different for the two nuclear genes. The frequency spectra of mutations indicated that differences in implied population structure among the three loci resulted from directional selection on the chloroplast genome and on the chromosomal segment containing adk. Collectively, these data suggest that long-distance migration within the Northern Hemisphere and Australasian regions is common (relative to the mutation rate) and that migration between these two regions, potentially via equatorial populations, is more frequent than migration among equatorial populations.     

Migration sources and pathways of the pest species Sogatella furcifera in Yunnan,China, and across the border inferred from DNA and wind analyses

The migration sources and pathways of Sogatella furcifera (Horváth) in topologically complex regions like Yunnan, China, and adjacent montane areas have long been a challenging task and a bottleneck in effective pest forecast and control. The present research reinvestigated this issue using a combination of mtDNA and long‐term historical wind field data in an attempt to provide new insights. Genetic analyses showed that the 60 populations of S. furcufera collected across Myanmar, Thailand, Laos, Vietnam, Yunnan, Guizhou, and Sichuan lack genetic structure and geographic isolation, while spatial analysis of haplotype and diversity indices discovered geographic relevance between populations. Migration rate analysis combined with high‐resolution 10‐year wind field analysis detected the following migration sources, pathways, and impacted areas which could explain the outbreak pattern in Yunnan. (a) Dominating stepwise northward migrations originated from northern Indochina, southern Yunnan, and central‐eastern Yunnan, impacting their northern areas. (b) Concurring summer–autumn southward (return) migration originated from nearly all latitude belts of Sichuan and Yunnan mainly impacting central and southern Yunnan. (c) Regular eastward and summer–autumn westward migrations across Yunnan. The northward migration reflects the temporal rhythm of gradual outbreaks from the south to the north in a year, while the return migration may explain the repeated or very severe outbreaks in the impacted areas. To form a better pest forecast and control network, attention must also be paid to the northern part of Yunnan to suppress the impact of return migration in summers and autumns.     

Decadal shifts in autumn migration timing by Pacific Arctic beluga whales are related to delayed annual sea ice formation

Migrations are often influenced by seasonal environmental gradients that are increasingly being altered by climate change. The consequences of rapid changes in Arctic sea ice have the potential to affect migrations of a number of marine species whose timing is temporally matched to seasonal sea ice cover. This topic has not been investigated for Pacific Arctic beluga whales (Delphinapterus leucas) that follow matrilineally maintained autumn migrations in the waters around Alaska and Russia. For the sympatric Eastern Chukchi Sea (‘Chukchi’) and Eastern Beaufort Sea (‘Beaufort’) beluga populations, we examined changes in autumn migration timing as related to delayed regional sea ice freeze‐up since the 1990s, using two independent data sources (satellite telemetry data and passive acoustics) for both populations. We compared dates of migration between ‘early’ (1993–2002) and ‘late’ (2004–2012) tagging periods. During the late tagging period, Chukchi belugas had significantly delayed migrations (by 2 to >4 weeks, depending on location) from the Beaufort and Chukchi seas. Spatial analyses also revealed that departure from Beaufort Sea foraging regions by Chukchi whales was postponed in the late period. Chukchi beluga autumn migration timing occurred significantly later as regional sea ice freeze‐up timing became later in the Beaufort, Chukchi, and Bering seas. In contrast, Beaufort belugas did not shift migration timing between periods, nor was migration timing related to freeze‐up timing, other than for southward migration at the Bering Strait. Passive acoustic data from 2008 to 2014 provided independent and supplementary support for delayed migration from the Beaufort Sea (4 day yr^?1) by Chukchi belugas. Here, we report the first phenological study examining beluga whale migrations within the context of their rapidly transforming Pacific Arctic ecosystem, suggesting flexible responses that may enable their persistence yet also complicate predictions of how belugas may fare in the future.     

Evolutionary history of Helicobacter pylori sequences reflect past human migrations in Southeast Asia

The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.     

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.     

Investigating connectivity and seasonal differences in wind assistance in the migration of Common Sandpipers

Many migratory bird species have undergone recent population declines, but there is considerable variation in trends between species and between populations employing different migratory routes. Understanding species-specific migratory behaviours is therefore of critical importance for their conservation. The Common Sandpiper Actitis hypoleucos is an Afro-Palaearctic migratory bird species whose European populations are in decline. We fitted geolocators to individuals breeding in England or wintering in Senegal to determine their migration routes and breeding or non-breeding locations. We used these geolocator data in combination with previously published data from Scottish breeding birds to determine the distributions and migratory connectivity of breeding (English and Scottish) and wintering (Senegalese) populations of the Common Sandpiper, and used simulated random migrations to investigate wind assistance during autumn and spring migration. We revealed that the Common Sandpipers tagged in England spent the winter in West Africa, and that at least some birds wintering in Senegal bred in Scandinavia; this provides insights into the links between European breeding populations and their wintering grounds. Furthermore, birds tagged in England, Scotland and Senegal overlapped considerably in their migration routes and wintering locations, meaning that local breeding populations could be buffered against habitat change, but susceptible to large-scale environmental changes. These findings also suggest that contrasting population trends in England and Scotland are unlikely to be the result of population-specific migration routes and wintering regions. Finally, we found that birds used wind to facilitate their migration in autumn, but less so in spring, when the wind costs associated with their migrations were higher than expected at random. This was despite the wind costs of simulated migrations being significantly lower in spring than in autumn. Indeed, theory suggests that individuals are under greater time pressures in spring than in autumn because of the time constraints associated with reproduction.     

Gene-flow between populations of cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is highly variable between years

Both large and small scale migrations of Helicoverpa armigera Hübner in Australia were investigated using AMOVA analysis and genetic assignment tests. Five microsatellite loci were screened across 3142 individuals from 16 localities in eight major cotton and grain growing regions within Australia, over a 38-month period (November 1999 to January 2003). From November 1999 to March 2001 relatively low levels of migration were characterized between growing regions. Substantially higher than average gene-flow rates and limited differentiation between cropping regions characterized the period from April 2001 to March 2002. A reduced migration rate in the year from April 2002 to March 2003 resulted in significant genetic structuring between cropping regions. This differentiation was established within two or three generations. Genetic drift alone is unlikely to drive genetic differentiation over such a small number of generations, unless it is accompanied by extreme bottlenecks and/or selection. Helicoverpa armigera in Australia demonstrated isolation by distance, so immigration into cropping regions is more likely to come from nearby regions than from afar. This effect was most pronounced in years with limited migration. However, there is evidence of long distance dispersal events in periods of high migration (April 2001-March 2002). The implications of highly variable migration patterns for resistance management are considered.