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1.
Uralic genes in Europe   总被引:6,自引:0,他引:6  
We have analysed data of three European populations speaking non-Indoeuropean languages: Hungarians, Lapps, and Finns. Principal coordinate analysis shows that Lapps are almost exactly intermediate between people located geographically near the Ural mountains and speaking Uralic languages, and central and northern Europeans. Hungarians and Finns are definitely closer to Europeans. An analysis of genetic admixture between Uralic and European ancestors shows that Lapps are slightly more than 50% European, Hungarians are 87% European, and Finns are 90% European. There is basic agreement between these conclusions and historical data on Hungary. Less is known about Finns and very little about Lapps.  相似文献   

2.
European Americans are often treated as a homogeneous group, but in fact form a structured population due to historical immigration of diverse source populations. Discerning the ancestry of European Americans genotyped in association studies is important in order to prevent false-positive or false-negative associations due to population stratification and to identify genetic variants whose contribution to disease risk differs across European ancestries. Here, we investigate empirical patterns of population structure in European Americans, analyzing 4,198 samples from four genome-wide association studies to show that components roughly corresponding to northwest European, southeast European, and Ashkenazi Jewish ancestry are the main sources of European American population structure. Building on this insight, we constructed a panel of 300 validated markers that are highly informative for distinguishing these ancestries. We demonstrate that this panel of markers can be used to correct for stratification in association studies that do not generate dense genotype data.  相似文献   

3.
H. G. Hall 《Genetics》1990,125(3):611-621
African honeybees, introduced into Brazil 33 years ago, have spread through most of South and Central America and have largely replaced the extant European bees. Due to a paucity of genetic markers, genetic interactions between European and African bees are not well understood. Three restriction fragment length polymorphisms (RFLPs), detected with random, nuclear DNA probes, are described. The polymorphisms are specific to bees of European descent, possibly specific to certain European races. Each European marker was found present at a high frequency in U.S. colonies but absent in South African bees. Previous mitochondrial DNA studies of neotropical bees have revealed negligible maternal gene flow from managed European apiaries into feral African populations. The findings reported here with nuclear DNA show paternal gene flow between the two but suggest asymmetries in levels of introgressive hybridization. Managed colonies in southern Mexico, derived from European maternal lines, showed diminished levels of the European nuclear markers, reflecting significant hybridization with African drones. The European alleles were present only at low frequencies in feral swarms from the same area. The swarms were of African maternal descent. In Venezuelan colonies, also derived from African maternal lines, the European markers were almost totally absent. The results point to limited paternal introgression from European colonies into the African honeybee populations. These findings dispute other views regarding modes of Africanization.  相似文献   

4.
Members of the European Parliament (MEPs) have voluntarily formed transnational political groups and invariably follow the voting instructions of these groups. This is intriguing as there are few obvious incentives for doing so. Unlike national parties, for example, the political groups in the European Parliament are not punished by the electorate if they are divided on key issues, as citizens know very little about what goes on inside the European Parliament. This paper pieces together an explanation of why the European political groups exist and why they have become so powerful by looking at the determinants of group cohesion and by undertaking a spatial analysis of voting in the European Parliament. MEPs who share preferences on a range of issues on the European Union policy agenda have an incentive to establish a division-of-labour contract and to share the costs of collecting information. Once internal party policy specialization and agenda setting has been established, MEPs have incentives to follow the voting instructions of their group owing to the advantages of cohesion in a context of repeated voting.  相似文献   

5.
Conclusions European cooperation in biological oceanography is indispensable for geographical, political and financial reasons. Large-scale regional projects, ocean observation and forescasting systems, the study of the deep-sea bed and the development of modern technology for automated observations require multinational cooperation. Other projects might be carried out on a bi- or trilateral basis. European cooperation holds great promise because of the high concentration and great variety of research institutions with a large potential of skilled personnel, instruments and many (too many?) research vessels of all sizes. The opening up of the former Eastern bloc provides new opportunities and obligations for European cooperation. New approaches have been found through the provision of national vessels and installations for international projects. The further integration of European marine science will presumably lead to the establishment of technology centres, and possibly to European research vessels. The new perspectives of European cooperation are encouraging, provided there will be enough solidarity within Europe during periods of great economic disparity, and provided European marine scientists are aware of the interests of their colleagues in all other parts of the world rich and poor.  相似文献   

6.
Abstract. The braconid parasitoid Asobara tabida Nees attacks larvae of several Drosophila species in fermenting substrates. Northwestern and central European populations of the parasitoid attack mainly D.subobscura Collin. Southern European parasitoids attack mainly D.melanogaster Meigen. Larvae of this last species can defend themselves against parasitoids by encapsulating the parasitoid egg. Parasitoids from southern European populations are better able to resist encapsulation of their eggs than their northwestern and central European conspecifics. The eggs of southern European parasitoids appear to have a 'sticky' egg chorion. As a result of this 'stickiness' the eggs become embedded in host tissue where they are not completely covered by the host's blood cells. This leads to, at most, partial encapsulation of the egg. Parasitoid larvae can escape from partially closed capsules.  相似文献   

7.
There is a cultural unity of Europe, notwithstanding the Reformation. This unity must be 'consciously' recognized, in order to develop the concept of European togetherness. The paper will examine the common roots of the European vocabulary, submitting the project for the compilation of some dictionaries, to which European colleagues will be called to contribute. European languages must be studied no more as 'national' languages, but in the context of the European tradition, emphasizing what they have in common, and not what separates them. Hence the necessity of compiling dictionaries on a new basis, of which early, summary indications are given.  相似文献   

8.
A few queens of the honeybee, Apis mellifera scutellata, were imported from Africa and released in Brazil in 1957. Progeny of these bees have now largely colonized the American tropics. Their imminent arrival in the United States poses a serious threat to the beekeeping industry and to agriculture dependent on honeybee pollination. African and European bees are morphologically very similar. DNA restriction fragment length polymorphisms are proving successful in distinguishing between the two. Several DNA markers specific to European honeybees have been described previously. Reported here are three cloned honeybee DNA probes that reveal polymorphisms that appear to be either African or European specific. Of fourteen alleles or haplotypes identified, five were present only in African and neotropical (Venezuelan and Mexican) African bees but absent in European-derived bees, two were present only in European-derived bees but absent in samples from South Africa. Another allele showed apparent frequency differences among populations. Such markers are useful in studying the genetics of neotropical African bee populations. Venezuelan and Mexican honeybee colonies show a preponderance of the African alleles with low levels of the European alleles. These observations of nuclear DNA, revealing limited paternal European introgression, together with previous mitochondrial DNA findings showing negligible European maternal gene flow into feral African populations, indicate that neotropical African bees are primarily African.  相似文献   

9.
The European flora is of global significance but many species are facing an ever increasing range of threats, especially the growing impacts of climate change. While various estimates have been made for the number of threatened plant species in Europe, an up-to-date European plant Red List does not presently exist. Target 8 of the Global Strategy for Plant Conservation (GSPC) calls for 60% of threatened plant species to be conserved in ex situ collections by 2010. In the absence of a European plant Red List, it is difficult to monitor progress at the regional level towards this target. To address this gap Botanic Gardens Conservation International (BGCI) has developed a consolidated list of European threatened species as a step towards a formal Red List. The database consists of national Red List data from 28 European countries and includes records for over 11,000 taxa. National Red List data were supplemented by information on the critically endangered plants of Europe provided by the Museum National d’Histoire Naturelle/European Topic Centre on Biological Diversity and the Conservatoire Botanique National de Brest. A list of regionally threatened species was extracted from the database and screened against BGCI’s database of plants in cultivation in botanic gardens (PlantSearch) and ENSCONET’s (European Native Seed Conservation Network) database of plants conserved in European seed banks. This analysis revealed that 42% of European threatened species are currently included in ex situ conservation programmes in Europe.  相似文献   

10.
Demography impacts the observed standing level of genetic diversity present in populations. Distinguishing the relative impacts of demography from selection requires a baseline of expressed gene variation in naturally occurring populations. Six nuclear genes were sequenced to estimate the patterns and levels of genetic diversity in natural Arabidopsis lyrata subsp. petraea populations that differ in demographic histories since the Pleistocene. As expected, northern European populations have genetic signatures of a strong population bottleneck likely due to glaciation during the Pleistocene. Levels of diversity in the northern populations are about half of that in central European populations. Bayesian estimates of historical population size changes indicate that central European populations also have signatures of population size change since the last glacial maxima, suggesting that these populations are not as stable as previously thought. Time since divergence amongst northern European populations is higher than amongst central European populations, suggesting that the northern European populations were established before the Pleistocene and survived glaciation in small separated refugia. Estimates of demography based on expressed genes are complementary to estimates based on microsatellites and transposable elements, elucidating temporal shifts in population dynamics and confirming the importance of marker selection for tests of demography.  相似文献   

11.
Results of hybridisation experiments involving five perennial European species of Brachypodium ( B. sylvaticum, B. glaucovirens, B. pinnatum, B. phoenicoides and B. retusum ), the annual B. distachyon , and the C. American perennial B. mexicanum are presented. Four of the European perennials are largely self-incompatible, whereas B. sylvaticum, B. distachyon and B. mexicanum are highly self-compatible. Despite their avowed ancient and relict status, the European species have mostly retained the ability to interbreed and produce viable F1 hybrids. The F1 hybrids obtained between the five European perennials all exhibit some degree of fertility. Hybrids between B. distachyon and at least some of the European perennials are vigorous and long-lived, but show no evidence of fertility. No hybrids involving B. mexicanum could be raised. Success in raising hybrids, and the degree of fertility of such hybrids, partly agrees with closeness of taxonomic relationships as measured by morphological, anatomical, biochemical and molecular characteristics, but also with closeness in chromosome number irrespective of taxonomic affinity. Hence some interspecific hybrids are more easily produced and are more fertile than certain intraspecific hybrids involving parents of different chromosome number. All hybrids form good numbers of bivalents, but meiosis varies from almost regular in hybrids between European perennials with the same chromosome number to very irregular in hybrids between B. distachyon and any perennial species.  相似文献   

12.
Hybridization can fuel evolutionary processes during biological invasions. The harlequin ladybird Harmonia axyridis has long been used as a biocontrol agent before the species became invasive worldwide. Previous analysis based on microsatellite data has shown that European invasive populations bear traces of admixture between an eastern North American source, which is at the origin of the worldwide invasion, and biocontrol strains used in Europe. In this study, we tested the hypothesis that this early admixture event may have fostered the European invasion by impacting on the phenotypes of wild European populations. Mean life history traits of experimental F(1) hybrids are compared with pure parental sources and wild European crosses. Our results reveal a biased impact whereby North American beetles benefitted from being admixed with European biocontrol strains. Resemblance between experimental hybrids and wild European invasive crosses further suggests a long-lasting effect of admixture that may still be at work and fostering invasiveness.  相似文献   

13.
This study compares the prevalence of chronic complications, the quality of metabolic control and the nutritional intake in people with type 1 diabetes in different European regions. The EURODIAB Complications Study included a sample of 3250 European patients with type 1 diabetes stratified for gender, age and diabetes duration. All examinations were performed using standardised, validated methods. HBA1c, LDL-cholesterol and fasting triglycerides were higher in the eastern European centres than in the southern or north-western European centres. Acute (severe ketoacidosis, severe hypoglycaemia) and chronic diabetes complications (retinopathy, nephropathy, neuropathy, cardiovascular disease) were all considerably more frequent in the eastern European centres. HbA1c was lower in the German centres than in the total EURODIAB cohort or in the north-western European centres, but severe hypoglycaemia and proliferative retinopathy were more common. Persons from the eastern European and the German centres consumed undesirably high amounts of cholesterol, total and saturated fat. Overall, improvements in the prevention, detection and management of diabetes complications in persons with type 1 diabetes are essential throughout Europe, particularly in eastern European regions. Since elevated LDL-cholesterol levels and hypertension were strikingly common in this relatively young cohort of European people with type 1 diabetes, generally more attention should be directed towards an adequate management of these cardiovascular risk factors.  相似文献   

14.
Conspectus of classes of European vegetation   总被引:1,自引:0,他引:1  
This is a first approximation to a Conspectus of classes of European vegetation. European vegetation consists, according to the present scheme, of 73 classes. An attempt was made to compile all available names of classes which have ever appeared in European phytosociological literature. The names were checked for nomenclatural accuracy. Lists of synonyms and related names are given. The classes, are characterised by a brief diagnosis, a comprehensive list of diagnostic species, and a list of basic references. Several syntaxonomic problems are discussed in the form of short notes.  相似文献   

15.
Each year, thousands of domestic Japanese and hybrid quails are released within the breeding range of the European quail. We showed recently that no post‐zygotic isolating mechanisms have yet been established between these subspecies. The aim of this study was to investigate whether pre‐zygotic mechanisms are strong enough to prevent hybridization. We tested the level of subspecies selectivity in females of European and Japanese quail respectively using playbacks of European, hybrid and Japanese male mating calls. European quail females emitted the greatest number of rally calls in response to mating calls by conspecific males. Their responses were the weakest to mating calls produced by males of the other subspecies and intermediate to mating calls by hybrid males. In contrast, Japanese quails produced similar responses to all types of mating calls. These results suggest that mixed pairs could form in the wild. The European quail could thus become one of the most endangered galliforms of the Western Palearctic.  相似文献   

16.
We have used binary markers and microsatellites on the Y chromosome to analyse diversity in a sample of Greenlandic Inuit males. This sample contains Y chromosomes typical of those found in European populations. Because the Y chromosome has a unique and robust phylogeny of a time depth that precedes the split between European and Native American populations, it is possible to assign chromosomes in an admixed population to either continental source. On this basis, 58+/-6% of these Y chromosomes have been assigned to a European origin. The high proportion of European Y chromosomes contrasts with a complete absence of European mitochondrial DNA and indicates strongly male-biased European admixture into Inuit. Comparison of the European component of Inuit Y chromosomes with European population data suggests that they have their origins in Scandinavia. There are two potential source populations: Norse settlers from Iceland, who may have been assimilated 500 years ago, and the Danish-Norwegian colonists of the eighteenth century. Insufficient differentiation between modern Icelandic and Danish Y chromosomes means that a choice between these cannot be made on the basis of diversity analysis. However, the extreme sex bias in the admixture makes the later event more likely as the source.  相似文献   

17.
Carolyn M. King 《Ecography》1991,14(3):173-185
From the close correlation between the body size of European stoats and the mean size of their vertebrate prey it ought to be possible to predict the body size of European stoats living on a prey fauna of a given size distribution. In New Zealand, stoats of European stock have lived for > 100 yr on a prey fauna containing fewer small and more large vertebrate prey than in Europe. They have become generally larger than their ancestors, as expected – especially the females. The vertebrate prey size index for New Zealand stoats extends the correlation predicted from European data. New Zealand stoats also eat large numbers of native insects. If these are included the local prey size indices are lower but still tend to vary with the substantial local variation in body size of stoats within New Zealand. Recent results from southern Ireland also fit the European correlation, but the few data so far available from Northern Ireland do not.  相似文献   

18.
Birds can optimize their migration either by minimizing time of transport, energy expenditure, or predation risk during migration. For each of these optimization criteria different fattening and stopover strategies are predicted. The first two of these optimization criteria are examined here for the bar-tailed godwit ( Limosa lapponica ). In the European Wadden Sea two populations of bar-tailed godwits stop over during spring migration between their wintering and breeding areas. The European population winters mainly in Great Britain and the western part of the Wadden Sea and breeds in Fennoscandia. The Afro-Siberian population winters in West Africa and breeds in Siberia. The European wintering population migrates to the eastern parts of Wadden Sea in March where it stays until early May. During this time birds gain 1.9 g d−1 in body mass for a 1500–2000-km non-stop flight to the breeding areas. Afro-Siberian birds stay only for one month in May in the Wadden Sea where they gain on average 9.4 g d−1 in mass for a 4000-km non-stop flight. Intake rates in April/May did not differ between the two populations (1.5 kJ min−1 and 1.8 kJ min−1 for Siberian and European migrants, respectively) but total energy intake was higher for the Siberian migrants, since they spend 50% of the day foraging vs 30% in the European birds. In contrast to European migrants, Afro-Siberian birds start to moult into breeding plumage already in their winter quarters. During their stopover in the Wadden Sea thermostatic costs are lower than at times when European birds are present. Thus, the higher energy demands of the Afro-Siberian birds seem to be fulfilled by a combination of physiological adaptations and a high working level. European birds seem to adopt an energy-minimized migration strategy whereas Afro-Siberian birds appear to follow a time-minimized migration.  相似文献   

19.
City rankings that aim to measure the environmental sustainability of European cities may contribute to the evaluation and development of environmental policy of European cities. The objective of this study is to identify and evaluate the methodological characteristics of these city rankings. First, a methodology was developed to systematically identify methodological characteristics of city rankings within different steps of the ranking development process. Second, six city rankings (European Energy Award, European Green Capital Award, European Green City Index, European Soot-free City Ranking, RES Champions League, Urban Ecosystem Europe) were examined. Official websites and any methodological documents found on those websites were content analyzed using the developed methodology. Interviews with representatives of the city rankings were conducted to acquire any additional information. Results showed that the city rankings varied greatly with respect to their methodological characteristics and that all city rankings had methodological weaknesses. Developers of city rankings are advised to use the methodology developed in this study to find methodological weaknesses and improve their ranking. In addition, developers ought to be more transparent about the methodological characteristics of their city rankings. End-users of city rankings are advised to use the developed methodology to identify and evaluate the methodological characteristics of city rankings before deciding to act on ranking results.  相似文献   

20.
Domesticated cattle were one of the cornerstones of European Neolithisation and are thought to have been introduced to Europe from areas of aurochs domestication in the Near East. This is consistent with mitochondrial DNA (mtDNA) data, where a clear separation exists between modern European cattle and ancient specimens of British aurochsen. However, we show that Y chromosome haplotypes of north European cattle breeds are more similar to haplotypes from ancient specimens of European aurochsen, than to contemporary cattle breeds from southern Europe and the Near East. There is a sharp north-south gradient across Europe among modern cattle breeds in the frequencies of two distinct Y chromosome haplotypes; the northern haplotype is found in 20 out of 21 European aurochsen or early domestic cattle dated 9500-1000 BC. This indicates that local hybridization with male aurochsen has left a paternal imprint on the genetic composition of modern central and north European breeds. Surreptitious mating between aurochs bulls and domestic cows may have been hard to avoid, or may have occurred intentionally to improve the breeding stock. Rather than originating from a few geographical areas only, as indicated by mtDNA, our data suggest that the origin of domestic cattle may be far more complex than previously thought.  相似文献   

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