Genetic Demography of Ukrainian Urban Populations in the 1990s: The Ethnic Composition of the Migration Flow in the Kharkov Population

Marriage records were used to study the dynamics of the migration flow into the population of Kharkov in 1960–1993. The decrease in the migration rate was accompanied by changes in the ethnic composition of the migrants. The entire migration flow from the republics of the Baltic region consisted of Russians and Ukrainians. The increase in the migration flow from Transcaucasia was mainly accounted for by the migration activity of indigenous populations. Most migrants from Moldova, Central Asia, Kazakhstan, and Kyrgyzstan were also representatives of the respective indigenous populations. Malecot's coefficient of isolation by distance (b) decreased from 0.00123 to 0.0081.     

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.     

Adaptive migratory divergence among sympatric brook charr populations

Ecological processes clearly contribute to population divergence, yet how they interact over complex life cycles remains poorly understood. Notably, the evolutionary consequences of migration between breeding and non-breeding areas have received limited attention. We provide evidence for a negative association between interpopulation differences in migration (between breeding and feeding areas, as well as within each) and the amount of gene flow (m) among three brook charr (Salvelinus fontinalis) populations inhabiting Mistassini Lake, Quebec, Canada. Individuals (n = 1166) captured throughout lake feeding areas over two consecutive sampling years were genotyped (10 microsatellites) and assigned to one of the three populations. Interpopulation differences in migration were compared based on spatial distribution overlap, habitat selection, migration distance within feeding areas, and morphology. We observed a temporally stable, heterogeneous spatial distribution within feeding areas among populations, with the extent of spatial segregation related to differential habitat selection (represented by littoral zone substrate). Spatial segregation was lowest and gene flow highest (m = 0.015) between two populations breeding in separate lake inflows. Segregation was highest and gene flow was lowest (mean m = 0.007) between inflow populations and a third population breeding in the outflow. Compared to outflow migrants, inflow migrants showed longer migration distances within feeding areas (64-70 km vs. 22 km). After entering natal rivers to breed, inflow migrants also migrated longer distances (35-75 km) and at greater elevations (50-150 m) to breeding areas than outflow migrants (0-15 km; -10-0 m). Accordingly, inflow migrants were more streamlined with longer caudal regions, traits known to improve swimming efficiency. There was no association between the geographic distance separating population pairs and the amount of gene flow they exchanged. Collectively, our results are consistent with the hypothesis that reduced gene flow between these brook charr populations results from divergent natural selection leading to interpopulation differences in migration. They also illustrate how phenotypic and genetic differentiation may arise over complex migratory life cycles.     

MIGRATION ENHANCES ADAPTATION IN BACTERIOPHAGE POPULATIONS EVOLVING IN ECOLOGICAL SINKS

Migration between populations can be a major evolutionary force. However, some disagreement exists as to precisely how migration affects population adaptation. Some theories emphasize the inhibitory effects of gene flow between locally adapted populations, whereas others propose that migration can enhance adaptation. Migration has also been theorized to rescue sink populations from extinction. In our experiments, we serially passaged bacteriophage Φ6 host range mutants under sink conditions on a novel host while manipulating the source and number of migrants into these experimental populations. Migrants from two sources were used: mutant Φ6 phage able to infect a novel host (treatment) and wild‐type Φ6 phage unable to infect a novel host (control). We used quadratic regressions to determine the relationship between the number of migrants per passage and the absolute fitnesses of experimental populations following 30 passages. Our results showed that migration from a control population had no effect on absolute fitnesses of our serially passaged populations following 30 passages. By contrast, the relationship between migrants per passage and absolute fitnesses for populations receiving migrants able to infect the novel host was best described by an upwardly concave curve. These results suggest that intermediate levels of migration can have favorable impacts on evolutionary adaptation.     

Craniometric variation of the Ainu: an assessment of differential gene flow from northeast Asia into northern Japan, Hokkaido

In and after the latest Neolithic period in Japan (approximately B.P. 2,300 years), there were two distinct waves of migration from eastern Asia. One is well known as successive episodes in which indigenous inhabitants of main-island Japan were intruded on by new arrivals with advanced technology, and of a different genetic stock. Another migration of people and culture, identified as the Okhotsk culture, reached the northeastern part of Hokkaido. As opposed to main-island Japan, the morphological continuity from the Neolithic to recent inhabitants in Hokkaido (Ainu) is notable, so that the evidence of admixture easily could have escaped notice. In this study, the effects of gene flow from an outside source on the pattern of among-group variation of Hokkaido Ainu are examined by means of two models. One is the R-matrix model comparing observed and expected craniometric variation for estimating differential external gene flow into a region. The other is a simple simulation model that estimates admixture in a population with two parental populations. The two approaches give similar results. The results suggest the possibility of admixture between the migrants from Northeast Asia, the Okhotsk culture people, and the indigenous inhabitants in Hokkaido during the 5th to 12th centuries A.D., at least in northeastern Hokkaido. Such gene flow may have a certain degree of effect on the genetic structure of recent Ainu. The findings further suggest morphological heterogeneity in Northeast Asia during the Holocene that has relevance for understanding the morphological heterogeneity seen through time in the New World.     

Biological affinities between migrant and parental populations of fishermen on the east coast of India.

We examined biological affinities between the migrant groups of fishermen in Puri and their parental counterparts using 3 sets of variables: genetic markers, anthropometric measurements, and quantitative dermatoglyphics. Results of both univariate and multivariate analyses suggest a significant migration effect, diversifying migrants from their parental populations, although the distance configurations based on each set of variables resemble each other. The migration effect is particularly remarkable for the anthropometric measurements. The plot of group centroids based on the discriminant analysis of the 7 populations depicts a clear segregation of migrants from the parental populations. Because of relatively large effective population sizes and short history of these populations in Puri, the role of genetic drift can be safely ruled out. However, a founder effect is a plausible reason for the observed differentiation of the migrants from their parental groups, especially given that certain rare variants that were not observed in the parental populations appear in the migrants. That the founders were a select group of fishermen with respect to body dimensions, not a random group, can be inferred from the occupational differences among the migrant groups, which in turn suggests phenotypic plasticity in the observed differentiation. Regression of mean phenotypic variance and heterozygosity on the distance from the centroid suggests a strong possibility of external gene flow into the migrant populations in Puri.     

Community composition, seasonal dynamics and interspecific correlation of waterbirds in the Qiantangjiang River estuary and Hangzhou Bay

Waterbird surveys were conducted regularly in the Qiantangjiang River estuary and Hangzhou Bay from July 2007 to November 2011. A total of 128 species (nine orders and 18 families) were recorded, including 119 migrants which accounted for 93% of the total species; eleven species were listed as National Protected Species. Inter-specific correlation analysis for 13 shorebird populations and nine duck populations recorded over time found that 21 pairs of shorebirds and 23 pairs of ducks were correlated. By looking at seasonal dynamics and migration patterns we were able to divide the migration process into six stages: (1) late July to late September was the migration peak of shorebirds, which were dominated by Limosa limosa, Calidris ruficollis and Charadrius mongolus. (2) Early October to mid-December was the migration peak of wintering migrants of shorebirds and ducks, which were the first two large groups in our study areas. (3) Late December to mid-February was the wintering period of migration waterbirds. (4) Late February to late March was the peak migration of ducks and the winter migrants of shorebirds dominated by Calidris alpina. (5) Early April to mid-May was the migration peak of passage migrants such as, Calidris ruficollis, Calidris acuminate and Limosa limosa but the population size of shorebird winter migrants dominated by Calidris alpine was still larger than the former. (6) Late May to mid-July was the breeding season of all egrets, summer migrants of gulls and several species of shorebirds. Our surveys show that interaction among species is possibly an important determinant of community composition of shorebirds and wintering ducks during the migration season. It may be the geographical position and community composition of migrant shorebirds across Hangzhou Bay that mean during the northward migration there are far more shorebirds than during the southward migration.     

Altitude, migration, and fertility in the Andes

In order to examine the relationship between hypoxia and reduced fertility of high Andean populations, a sample of 241 females living in the low-altitude Tambo Valley of Peru was studied. 63 of the subjects were born in the low-altitude valley, 121 were migrants from high altitudes, and 57 were migrants born in low altitudes. The rate of abortion was low among high-altitude subjects before they migrated, but became greater after migrating. It was found that the high-altitude populations had almost twice as long parity intervals than the low-altitude populations. Compared to migrants born at low altitudes, the high-altitude-born subjects who migrated to low altitudes had higher fertility rates. The results of the study are consistent with the hypothesis that high altitudes, through anoxia, have a lowering effect on fertility. Of the several possible explanations which might account for the increase in fertility of downward migrants on migration from high to low altitude (migration, socioeconomic factors, acculturation, seasonal male emigration from high altitude, and removal of hypoxia stress), altitude appears to be the most significant.     

Seeing ghosts: the effect of unsampled populations on migration rates estimated for sampled populations

In 2004, the term 'ghost population' was introduced to summarize the effect of unsampled subpopulations that exchange migrants with other subpopulations that have been sampled. Estimated long-term migration rates among populations sampled will be affected by ghost populations. Although it would be convenient to be able to define an apparent migration matrix among sampled populations that incorporate the exchange of migrants with ghost populations, no such matrix can be defined in a way that predicts all features of the coalescent process for the true migration matrix. This paper shows that if the underlying migration matrix is symmetric, it is possible to define an apparent migration matrix among sampled subpopulations that predicts the same within-population and between-population homozygosities among sampled populations as is predicted by the true migration matrix. Application of this method shows that there is no simple relationship between true and apparent migration rates, nor is there a way to place an upper bound on the effect of ghost populations. In general, ghost populations can create the appearance of migration between subpopulations that do not actually exchange migrants. Comparison with published results from the application of the program, MIGRATE, shows that the apparent migration rates inferred with that program in a three-subpopulation model differ from those based on pairwise homozygosities. The apparent migration matrix determined by the method described in this paper probably represents the upper bound on the effect of ghost populations.     

被动迁移在抗性进化中的作用

为了明确迁移和基因交流在杀虫剂抗性基因进化中的作用,我们从四个不同的地区采集有机磷抗性的库蚊野生种群,利用淀粉电泳鉴定了各种群中存在的已知过量产生酯酶的分布频率,并通过5个假定的中性位点的电泳多态性分析了种群间的遗传多样性。结果表明种群间的基因交流是存在的,遗传分化与地理位置存在一定关系,而抗性等位基因A2一B2的分布却与种群间的遗传分化不一致。对这种差异的解释是：被动迁移(铁路运输等)加速了抗性基因的交流,而当抗性基因以自然迁飞的方式向周围地区扩散时,却是一个相对缓慢的过程。     

Process in the evolution of bird migration and pattern in avian ecogeography

Current ideas about the evolution of bird migration equate its origin with the first appearance of fully migratory populations, and attribute its evolution to a selective advantage generated by increased breeding success, gained through temporary emigration from resident populations to breed in under-exploited seasonal areas. I propose an alternative hypothesis in which migration first appears as a temporary directional shift away from the breeding site outside the reproductive period, in response to seasonal variation in the direction and/or severity of environmental gradients. Fully migratory populations then appear through either extinction of sedentary phenotypes, or colonisation of vacant seasonal areas by migrants. Where colonisation occurs, resident ancestral populations can be driven to extinction by competition from migrants which invade their range outside the breeding season, resulting in fully migratory species. An analogous process drives the evolution of migration between high latitudes and the tropics, since extension of breeding range into higher latitudes may drive low latitude populations to extinction, resulting in an overall shift of breeding range. This process can explain reverse latitudinal gradients in avian diversity in the temperate zone, since the breeding ranges of migratory species concentrate in latitudes where they enjoy the highest breeding success. Near absence of forest-dwelling species among Palaearctic-African migrants is attributable to the lack of forest in northern Africa for much of the Tertiary, which has precluded selection both for southward extension of migration by west Palaearctic forest species, and northward breeding colonisation by African forest species.     

Compensatory releases reduce genetic differentiation among Atlantic salmon populations in the Baltic Sea: evidence from the River Ume‐Vindelälven

About 90% of salmon smolts in the Baltic Sea derive from hatchery enhancement programmes designed to compensate for loss of catches and genetic resources due to the damming of salmon rivers. The potential threat of genetic homogenization from extensive hatchery releases, however, has not been thoroughly investigated. We provide evidence that straying from deliberate releases poses a threat to indigenous populations by identifying the origin of 127 fin‐clipped (hatchery) salmon caught in the River Ume‐Vindelälven during 1997 to 2000, using mtDNA and six microsatellite loci. The analysis of eight potential donor stocks revealed that compensatory releases from the R. Ångerman and R. Luleälven hatcheries have resulted in a significant amount of straying to the river Ume‐Vindelälven (at least 10 and 12 migrants per year). As predicted to due to increased migration, the analysis of temporal samples from the wild population of R. Vindelälven showed a decreasing trend in genetic differentiation estimates (measured as Fst) relative to hatchery the hatchery strains of R. Ångermanälven and R. Luleälven. Our results suggest that gene flow from compensatory releases poses a serious threat to the genetic makeup of the existing wild populations in the Baltic.     

Biological Affinities Between Migrant and Parental Populations in Punjab, India

In the present study, we have examined biological affinities between parental population, migrants from Pakistan after 1947 and non-Punjabi migrants from other states of India in Punjab. About 500 adult individuals of both sexes from 300 families among three groups were measured for 16 anthropometric and physiometric variables. Analysis of both univariate and multivariate suggests an overall significant migration effect in almost all variables especially anthropometric measurements between both sexes. The higher discrimination has been found in migrants from other states of India with reference to anthropometric traits as compared to other two populations. This is because of more genetic heterogeneity as would be expected from many states and many ethnicities of migrants. It was also found that the other two populations are more or less qualitatively similar, which reflects common ethnohistorical or geographic affiliations. However, overall, women showed a greater migration effect than men.     

SIGNIFICANCE OF PASSIVE MIGRATION IN EVOLUTION OF INSECTICIDE RESISTANCE IN THE MOSQUITO CULEX PIPIENS (DIPTERA: CULICIDAE)

In order to determine the combined effects of migration and gene flow on evolution of insecticide resistance in the mosquito Culex pipiens, four samples were collected in China, among which two were collected along the railway from Beijing to Guangzhou. Bioassay data showed that the resistance levels of the four populations to dichlorvos were high and to parathion moderate as compared with the susceptible strain and there was no significant difference among the four populations to the same organophosphate (OP) insecticide. Starch electrophoresis was done to identify the frequency of known overproduced esterases and to analyze genetic diversity among various populations by electrophoretic polymorphism of five presumably neutral loci. The results indicated that the gene flow between populations existed and the number of effective migrants (Nm) was related to collection geography (Nm from 1.67 to 40.07). In contrast with lower genetic differentiation between two nearby populations (between GZ and ZS, ZZ and SQ) and higher genetic differentiation between two distant populations (between GZ and ZZ), there was a significant and inconsistent difference in the distribution of resistance alleles, A2‐B2 when explained only with active migration. This divergent situation could be straightened out when considering passive migration (such as railway transport) which increased the spread of A2‐B2 along the railway, i.e., in GZ and ZZ. The resistance alleles, A2‐B2, dispersing to around areas by active migration suffered from the limitation of gene flow and the speed of invasion.     

Contrasting Patterns of Genetic Differentiation among Blackcaps (Sylvia atricapilla) with Divergent Migratory Orientations in Europe

Migratory divides are thought to facilitate behavioral, ecological, and genetic divergence among populations with different migratory routes. However, it is currently contentious how much genetic divergence is needed to maintain distinct migratory behavior across migratory divides. Here we investigate patterns of neutral genetic differentiation among Blackcap (Sylvia atricapilla) populations with different migratory strategies across Europe. We compare the level of genetic divergence of populations migrating to southwestern (SW) or southeastern (SE) wintering areas with birds wintering in the British Isles following a recently established northwesterly (NW) migration route. The migratory divide between SW and SE wintering areas can be interpreted as a result of a re-colonization process after the last glaciation. Thus we predicted greater levels of genetic differentiation among the SW/SE populations. However, a lack of genetic differentiation was found between SW and SE populations, suggesting that interbreeding likely occurs among Blackcaps with different migratory orientations across a large area; therefore the SW/SE migratory divide can be seen as diffuse, broad band and is, at best, a weak isolating barrier. Conversely, weak, albeit significant genetic differentiation was evident between NW and SW migrants breeding sympatrically in southern Germany, suggesting a stronger isolating mechanism may be acting in this population. Populations located within/near the SW/SE contact zone were the least genetically divergent from NW migrants, confirming NW migrants likely originated from within the contact zone. Significant isolation-by-distance was found among eastern Blackcap populations (i.e. SE migrants), but not among western populations (i.e. NW and SW migrants), revealing different patterns of genetic divergence among Blackcap populations in Europe. We discuss possible explanations for the genetic structure of European Blackcaps and how gene flow influences the persistence of divergent migratory behaviors.     

Are temporary migrants escapees of the one-child-per-family population policy: a revisit to the detachment hypothesis

Using Hubei province as a case study, this paper retests the detachment hypothesis against the three conventional hypotheses regarding migration-fertility linkage (i.e., selectivity, disruption, and adaptation hypotheses) in explaining migrant and non-migrant fertility differentials in China. The analysis of yearly order-specific birth probabilities suggests that temporary migrants exhibit a significantly higher probability of having a second or higher order birth than comparable permanent migrants and non-migrants. This higher fertility among temporary migrants occurs after migration; temporary migrants actually do not differ from non-migrants in fertility before migration. But permanent migrants experience no significant change in their fertility after migration. The results lend a strong support to the detachment hypothesis, which best explains the fertility differentials between migrant and non-migrant populations in contemporary China; the separation of temporary migrants' actual residence from their official one does lead to a greater likelihood among temporary migrants to have unplanned births.     

Three ways of assessing metapopulation structure in the butterfly Plebejus argus

1. Three independent methods were used to investigate population structure in the butterfly Plebejus argus . First, migration and dispersal ability were measured by mark–release–recapture in seven adjacent habitat patches, and by release of butterflies in unoccupied habitat. Secondly, colonization of newly created habitat was observed over 7 years. Finally, genetic differentiation of local populations within a metapopulation was investigated. Sampled local populations included parts of the mark–release–recapture study area.
2. Plebejus argus is relatively sedentary: the maximum movement detected was 395 m, and only 2% of individuals moved further than 100 m between recaptures on different days. None the less, adjacent local populations in the mark–release–recapture study area were linked by occasional migration, with ≈ 1.4% of individuals moving between patches separated by 13–200 m.
3. Despite low mobility, observed colonizations occurred rapidly over distances of 1 km. Because P. argus occurs at high population densities, 1.4% migration can generate enough migrants to colonize newly suitable habitat quickly at this spatial scale.
4. Mark–release–recapture data were used to predict that there would be limited genetic differentiation through drift between local populations at this spatial scale. The prediction was supported by allele frequency data for the same local populations.
5. Genetic differentiation often indicates higher levels of migration than are revealed by the movements of marked individuals. This study shows that when experimental releases and extensive marking are undertaken in areas that are large relative to most movements, indirect measures of gene flow and direct measures of dispersal can concur.
6. Evidence from the three different approaches was complementary, indicating that P. argus occurs as metapopulations within the study area.     

Population structure in the highly fragmented range of Tor douronensis (Cyprinidae) in Sarawak, Malaysia revealed by microsatellite DNA markers

1. Understanding the structure of threatened populations, particularly those that exist in degraded or fragmented habitats is crucial for their effective management and conservation. Recently developed methods of individual-based analysis of genetic data provide an unprecedented opportunity to understand the relationships amongst fragmented populations.
2. In the present study, population structure of an important cyprinid species ( Tor douronensis ), which is indigenous to Sarawak, Malaysia, is investigated as part of an ongoing conservation effort to restore threatened wild populations of the species. The population structure inferred using data from seven autosomal microsatellite loci was generally consistent with geography and habitat fragmentation.
3. The results indicate that there are two well-defined clusters of T. douronensis in Sarawak, namely the 'northeastern' and the 'southwestern' clusters. In addition, a further subdivision was observed in each of the clusters distributed between river systems. Low levels of gene flow were also observed and migrants between habitat fragments were identified, possibly resulting from human-mediated translocations.
4. Implications of the findings for management and conservation of T. douronensis are discussed.     

Admixture and Gene Flow from Russia in the Recovering Northern European Brown Bear (Ursus arctos)

Large carnivores were persecuted to near extinction during the last centuries, but have now recovered in some countries. It has been proposed earlier that the recovery of the Northern European brown bear is supported by migration from Russia. We tested this hypothesis by obtaining for the first time continuous sampling of the whole Finnish bear population, which is located centrally between the Russian and Scandinavian bear populations. The Finnish population is assumed to experience high gene flow from Russian Karelia. If so, no or a low degree of genetic differentiation between Finnish and Russian bears could be expected. We have genotyped bears extensively from all over Finland using 12 validated microsatellite markers and compared their genetic composition to bears from Russian Karelia, Sweden, and Norway. Our fine masked investigation identified two overlapping genetic clusters structured by isolation-by-distance in Finland (pairwise F_ST = 0.025). One cluster included Russian bears, and migration analyses showed a high number of migrants from Russia into Finland, providing evidence of eastern gene flow as an important driver during recovery. In comparison, both clusters excluded bears from Sweden and Norway, and we found no migrants from Finland in either country, indicating that eastern gene flow was probably not important for the population recovery in Scandinavia. Our analyses on different spatial scales suggest a continuous bear population in Finland and Russian Karelia, separated from Scandinavia.     

THE EFFECT OF DELAYED POPULATION GROWTH ON THE GENETIC DIFFERENTIATION OF LOCAL POPULATIONS SUBJECT TO FREQUENT EXTINCTIONS AND RECOLONIZATIONS

I investigated the effects of delayed population growth on the genetic differentiation among populations subjected to local extinction and recolonization, for two different migration functions; (1) a constant migration rate, and (2) a constant number of migrants. A delayed period of population growth reduces the size of the newly founded populations for one or several generations. Whether this increases differentiation among local populations depends on the actual pattern of migration. With a constant migration rate, fewer migrants move into small populations than into large, thus providing ample opportunity for drift to act within a population. A prolonged period of population growth thus makes the conditions for enhanced differentiation between local populations less restrictive and also inflates the actual levels of differentiation. The effect depends on the relative magnitudes of k_e, the effective number of colonizers and k, the actual number of colonizers. When there is a constant number of migrants into a population per generation, migration into small populations is increased. This increase of migration in small populations counteracts the effects of genetic drift due to small population size. It increases the rate by which populations approach equilibrium, as small populations are swamped by migrants from larger populations closer to genetic equilibrium, and overall levels of differentiation are thus reduced. I also discuss situations for which the results of this paper are relevant.