Post by Διαμονδ on Dec 13, 2017 11:08:18 GMT
Scientists have described genetic differences of populations of different regions of the UK and found traces of ancient migrations
The researchers created the first detailed map of genetic structure of populations of the UK. It turned out that the Celtic population of the territory is not homogeneous genetically, and most ancient gene pool survived in Wales. The DNA comparison of the British and continental Europeans pointed to the genetic profile of ancestors for each region. The gene pool of modern population was able to see the reflection of the most important events in the history of the colonization of the British Isles.
The study of genetic differences among modern populations helps to look deep into the history and see the traces of the migrations of population groups that have formed the modern gene pool. This work was carried out by an international group of researchers under the guidance of British experts from the University of Oxford and University College London in their paper published in the journal Nature on March 19. Walter Bodmer, Peter Donnelly and colleagues analyzed the genetic structure of the UK population. They not only built a very accurate genetic map modern British populations, but also found traces major historical migrations and specify the nature of the settlement of the British Isles.
The gene pool reflects the geography
The researchers collected DNA 2039 people from different areas of the UK. When choosing they were guided by this rule: all human ancestors in the third generation (both grandparents and both parents) must live not further than 80 km from each other. This condition allowed us to obtain a "snapshot" of the genetic structure of British populations of the late XIX-early XX century.
For DNA comparison, scientists used more than 500 thousand single-nucleotide polymorphisms (SNP) scattered throughout the genome. Their analysis was performed using statistical methods fineSTRUCTURE and GLOBETROTTER. These methods DNA samples were distributed across clusters based on their similarities, and regardless of which part of Britain they are collected. And by placing a sample of each person to a point in the middle from the places of birth of his grandparents, they had the opportunity to see how genetic similarity correlates with geographical location.
The coincidence was astounding. As can be seen in the figure, 17 genetic clusters distributed on the map according to the geographical location of samples. Different clusters practically do not overlap. As these clusters are formed from all samples without regard to their geography, then, is correspondence reflect the real genetic diversity of populations, stress the authors.
The most genetically diverse was the population of the County of Orkney on the Orkney Islands North of Scotland, it includes three clusters. Genetic differences clearly emerge among the different areas of the UK: Northern England, Scotland and Northern Ireland together are different from the South of England, North Wales is different from South, and Cornwall forms a separate cluster. The boundaries of the clusters often coincide with modern borders of historical provinces, for example, on the border of Cornwall and Devon, on the border of England and Wales. The largest cluster (marked on the map by red squares) covers most of Central and southern England and the East coast. It brings together almost half included in the study samples of DNA.
The authors constructed a phylogenetic tree of the British population, showing how to form the clusters, how was the separation of the major branches. As can be seen on the tree at a very early stage separated branch of the population of the Orkney Islands, separated Wales. Subsequent the fork of a tree led to the separation of North and South Wales, the Department of the North of England, Scotland and Northern Ireland from the rest of England and the separation of Cornwall from the rest of the clusters.
Thus, it did not confirm the idea of genetic homogeneity of the Celtic population of great Britain as the most ancient, experienced the influence of the Saxon migration. On the contrary, the Celtic part of the UK (Scotland, Northern Ireland, Wales and Cornwall) were much more genetically diverse than the rest of the territory.
Despite the fact that the clusters within the British population clearly stand out, when scientists measured the genetic distance between them, it was small (mean of 0.002, a maximum of 0,007). This means that the observed differences are very subtle, they can be seen only with a strong "increasing", which was created by researchers with powerful statistical methods. For comparison, they analyzed their data by standard methods – principal component analysis (PCA) and ADMIXTURE. Both methods showed the separation of the branches of Orkney and Wales, but did not reveal more subtle population genetic structure.
Continental trace in the genome of the British
Genetic variation within British populations may be the result of exclusion of certain groups from each other, and also to reflect the contribution of different migrations and mixing of migrants with the indigenous population. To deal with the latter, the researchers used the same method for comparison of DNA samples of the British population samples of more than 6 thousand inhabitants of continental Europe from 10 countries. These samples according to the genetic similarity was divided into 51 group.
For each cluster, the British researchers assessed the contribution of each continental group determined the genetic profile of ancestors. The analysis showed that some European groups, such as West Germany, the Flemish part of Belgium, northwestern France, South of France and Spain, brought a significant contribution to the origin of almost all British clusters. Others contribute only in some specific clusters, for example, Norwegian has had a significant impact on the formation of clusters in Orkney and less in Scotland and Northern Ireland.
The gene pool reflects the history
Genetic data reflected the traces of the migrations to the British Isles during the last 10 thousand years. The nature of the influence of the continental groups on the British cluster, the researchers distinguish the relative time of migration events. Those groups whose contribution is found in all clusters clearly indicate a more ancient migration. Since then, enough time has passed that their haplotypes have spread to other parts of the UK. Continental trail in a separate cluster, obviously the result of more recent migrations.
The most notable impression left by the conquest of Britain by the Anglo-Saxons in the V century. The genetic contribution of the Anglo-Saxon migration is significant in the South-Eastern, Central and southern England, although it never exceeds 50%, and most of the territory is 10 to 40%. This suggests that the Anglo-Saxons did not fully supplanted the local population of the Britons (Celts), and mixed with it. Some clusters topographically coincide with the territories of the Anglo-Saxon kingdoms and clans. It seems that these areas have retained their ethnographic and genetic uniqueness, for many centuries, the researchers note.
In populations of the Orkney Islands 25% of the gene pool is related to the ancestors of Norwegian origin, it traces the invasion of the Islands the Norwegian Vikings that occurred in the IX century. Genetic data indicate that the Norwegian Vikings did not supplant the indigenous population and mixed with it. But a clear genetic traces of the Danish Vikings, who at the same time controlled a large part of England, could not be found.
Regarding the earliest settlement of the British Isles – after the end of the last glaciation, the traces are best preserved in the populations of Wales. Data indicate successive significant migration from the continent before the conquest of Britain by the Roman Empire in the early first Millennium ad, the Genetic impact of this migration spread across England, Scotland and Northern Ireland, but almost bypassed Wales, which preserved the most ancient gene pool.
The authors convincingly showed how genetics can Supplement and clarify the archaeological and linguistic information in order to reconstruct the history of populations. To obtain a detailed genetic map of the country and to look into the past of the British population helped them a competent selection of the source data and powerful statistical methods.
xn--c1acc6aafa1c.xn--p1ai/?page_id=2374
The researchers created the first detailed map of genetic structure of populations of the UK. It turned out that the Celtic population of the territory is not homogeneous genetically, and most ancient gene pool survived in Wales. The DNA comparison of the British and continental Europeans pointed to the genetic profile of ancestors for each region. The gene pool of modern population was able to see the reflection of the most important events in the history of the colonization of the British Isles.
The study of genetic differences among modern populations helps to look deep into the history and see the traces of the migrations of population groups that have formed the modern gene pool. This work was carried out by an international group of researchers under the guidance of British experts from the University of Oxford and University College London in their paper published in the journal Nature on March 19. Walter Bodmer, Peter Donnelly and colleagues analyzed the genetic structure of the UK population. They not only built a very accurate genetic map modern British populations, but also found traces major historical migrations and specify the nature of the settlement of the British Isles.
The gene pool reflects the geography
The researchers collected DNA 2039 people from different areas of the UK. When choosing they were guided by this rule: all human ancestors in the third generation (both grandparents and both parents) must live not further than 80 km from each other. This condition allowed us to obtain a "snapshot" of the genetic structure of British populations of the late XIX-early XX century.
For DNA comparison, scientists used more than 500 thousand single-nucleotide polymorphisms (SNP) scattered throughout the genome. Their analysis was performed using statistical methods fineSTRUCTURE and GLOBETROTTER. These methods DNA samples were distributed across clusters based on their similarities, and regardless of which part of Britain they are collected. And by placing a sample of each person to a point in the middle from the places of birth of his grandparents, they had the opportunity to see how genetic similarity correlates with geographical location.
The coincidence was astounding. As can be seen in the figure, 17 genetic clusters distributed on the map according to the geographical location of samples. Different clusters practically do not overlap. As these clusters are formed from all samples without regard to their geography, then, is correspondence reflect the real genetic diversity of populations, stress the authors.
The most genetically diverse was the population of the County of Orkney on the Orkney Islands North of Scotland, it includes three clusters. Genetic differences clearly emerge among the different areas of the UK: Northern England, Scotland and Northern Ireland together are different from the South of England, North Wales is different from South, and Cornwall forms a separate cluster. The boundaries of the clusters often coincide with modern borders of historical provinces, for example, on the border of Cornwall and Devon, on the border of England and Wales. The largest cluster (marked on the map by red squares) covers most of Central and southern England and the East coast. It brings together almost half included in the study samples of DNA.
The authors constructed a phylogenetic tree of the British population, showing how to form the clusters, how was the separation of the major branches. As can be seen on the tree at a very early stage separated branch of the population of the Orkney Islands, separated Wales. Subsequent the fork of a tree led to the separation of North and South Wales, the Department of the North of England, Scotland and Northern Ireland from the rest of England and the separation of Cornwall from the rest of the clusters.
Thus, it did not confirm the idea of genetic homogeneity of the Celtic population of great Britain as the most ancient, experienced the influence of the Saxon migration. On the contrary, the Celtic part of the UK (Scotland, Northern Ireland, Wales and Cornwall) were much more genetically diverse than the rest of the territory.
Despite the fact that the clusters within the British population clearly stand out, when scientists measured the genetic distance between them, it was small (mean of 0.002, a maximum of 0,007). This means that the observed differences are very subtle, they can be seen only with a strong "increasing", which was created by researchers with powerful statistical methods. For comparison, they analyzed their data by standard methods – principal component analysis (PCA) and ADMIXTURE. Both methods showed the separation of the branches of Orkney and Wales, but did not reveal more subtle population genetic structure.
Continental trace in the genome of the British
Genetic variation within British populations may be the result of exclusion of certain groups from each other, and also to reflect the contribution of different migrations and mixing of migrants with the indigenous population. To deal with the latter, the researchers used the same method for comparison of DNA samples of the British population samples of more than 6 thousand inhabitants of continental Europe from 10 countries. These samples according to the genetic similarity was divided into 51 group.
For each cluster, the British researchers assessed the contribution of each continental group determined the genetic profile of ancestors. The analysis showed that some European groups, such as West Germany, the Flemish part of Belgium, northwestern France, South of France and Spain, brought a significant contribution to the origin of almost all British clusters. Others contribute only in some specific clusters, for example, Norwegian has had a significant impact on the formation of clusters in Orkney and less in Scotland and Northern Ireland.
The gene pool reflects the history
Genetic data reflected the traces of the migrations to the British Isles during the last 10 thousand years. The nature of the influence of the continental groups on the British cluster, the researchers distinguish the relative time of migration events. Those groups whose contribution is found in all clusters clearly indicate a more ancient migration. Since then, enough time has passed that their haplotypes have spread to other parts of the UK. Continental trail in a separate cluster, obviously the result of more recent migrations.
The most notable impression left by the conquest of Britain by the Anglo-Saxons in the V century. The genetic contribution of the Anglo-Saxon migration is significant in the South-Eastern, Central and southern England, although it never exceeds 50%, and most of the territory is 10 to 40%. This suggests that the Anglo-Saxons did not fully supplanted the local population of the Britons (Celts), and mixed with it. Some clusters topographically coincide with the territories of the Anglo-Saxon kingdoms and clans. It seems that these areas have retained their ethnographic and genetic uniqueness, for many centuries, the researchers note.
In populations of the Orkney Islands 25% of the gene pool is related to the ancestors of Norwegian origin, it traces the invasion of the Islands the Norwegian Vikings that occurred in the IX century. Genetic data indicate that the Norwegian Vikings did not supplant the indigenous population and mixed with it. But a clear genetic traces of the Danish Vikings, who at the same time controlled a large part of England, could not be found.
Regarding the earliest settlement of the British Isles – after the end of the last glaciation, the traces are best preserved in the populations of Wales. Data indicate successive significant migration from the continent before the conquest of Britain by the Roman Empire in the early first Millennium ad, the Genetic impact of this migration spread across England, Scotland and Northern Ireland, but almost bypassed Wales, which preserved the most ancient gene pool.
The authors convincingly showed how genetics can Supplement and clarify the archaeological and linguistic information in order to reconstruct the history of populations. To obtain a detailed genetic map of the country and to look into the past of the British population helped them a competent selection of the source data and powerful statistical methods.
xn--c1acc6aafa1c.xn--p1ai/?page_id=2374