Angela
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[h=3]Y-chromosomal sequencing and screening reveal both stability and migrations in North Eurasian populations. Balanovsky et al[/h]https://ep70.eventpilot.us/web/page.php?page=IntHtml&project=ASHG16&id=160121213
"Y-chromosomal markers exhibit the highest interpopulation diversity in the genome and thus form one of the most informative tools for tracing population history. However, their information value depends on discovering SNPs which subdivide haplogroups with broad geographic distribution into branches revealing fine population structure. Progress in such discoveries has recently moved from a slow linear phase to a rapid exponential phase due to NGS.
We applied this approach to the Y-chromosomal pool of North Eurasian populations and concentrated on haplogroups C, G1, G2, N1b, N1c, and R1b. We sequenced 181 Y-chromosomes (capturing 11 Mb from each sample), developed the NGSConv software for calling Y-chromosomal SNPs, and identified roughly 2,500 SNPs, most of which were new. Then we constructed phylogenetic trees and dated dozens of their branches using our estimates of the mutation rate. The last – but not the least – step included screening branch-defining SNPs in the entire Biobank of indigenous North Eurasian populations (led by prof. Elena Balanovska), which includes 26,000 samples from 260 populations. This screening resulted in frequency distribution maps of 29 branches of haplogroups R1b and C, thus increasing the phylogenetic resolution by an order of magnitude compared to the two initial haplogroups.
For haplogroup R1b, we identified a previously unstudied “eastern” branch, R1b-GG400, found in East Europeans and West Asians and forming a brother clade to the “western” branch R1b-L51 found in West Europeans. The ancient samples from the Yamnaya archaeological culture are located on this eastern branch, showing that the paternal descendants of the Yamnaya population – in contrast to the published autosomal findings - still live in the Pontic steppe and were not an important source of paternal lineages in present-day West Europeans.
For haplogroup C-M217 - the predominant paternal component in Central Asians - we found signals of simultaneous expansion in two independent branches. Both expansion times and gene geographic maps of the expanded lineages indicated the emergence of the Mongol Empire as the likely trigger.
We conclude that simply discovering new SNP is not enough, but in combination with screening for the branch-defining SNPs in large biobanks of indigenous populations, it allows comprehensive reconstruction of male population history.
The study was supported by the Russian Science Foundation grant 14-14-00827 to OB."
That seems like a rather sweeping generalization to draw from the data in terms of R1b, although of course we have to wait and see the paper itself.
If the brother clade of L51 is in the Yamnaya samples we have, why wouldn't it be likely that L51 is west of that in the still largely unsampled areas of western Yamnaya?
"Y-chromosomal markers exhibit the highest interpopulation diversity in the genome and thus form one of the most informative tools for tracing population history. However, their information value depends on discovering SNPs which subdivide haplogroups with broad geographic distribution into branches revealing fine population structure. Progress in such discoveries has recently moved from a slow linear phase to a rapid exponential phase due to NGS.
We applied this approach to the Y-chromosomal pool of North Eurasian populations and concentrated on haplogroups C, G1, G2, N1b, N1c, and R1b. We sequenced 181 Y-chromosomes (capturing 11 Mb from each sample), developed the NGSConv software for calling Y-chromosomal SNPs, and identified roughly 2,500 SNPs, most of which were new. Then we constructed phylogenetic trees and dated dozens of their branches using our estimates of the mutation rate. The last – but not the least – step included screening branch-defining SNPs in the entire Biobank of indigenous North Eurasian populations (led by prof. Elena Balanovska), which includes 26,000 samples from 260 populations. This screening resulted in frequency distribution maps of 29 branches of haplogroups R1b and C, thus increasing the phylogenetic resolution by an order of magnitude compared to the two initial haplogroups.
For haplogroup R1b, we identified a previously unstudied “eastern” branch, R1b-GG400, found in East Europeans and West Asians and forming a brother clade to the “western” branch R1b-L51 found in West Europeans. The ancient samples from the Yamnaya archaeological culture are located on this eastern branch, showing that the paternal descendants of the Yamnaya population – in contrast to the published autosomal findings - still live in the Pontic steppe and were not an important source of paternal lineages in present-day West Europeans.
For haplogroup C-M217 - the predominant paternal component in Central Asians - we found signals of simultaneous expansion in two independent branches. Both expansion times and gene geographic maps of the expanded lineages indicated the emergence of the Mongol Empire as the likely trigger.
We conclude that simply discovering new SNP is not enough, but in combination with screening for the branch-defining SNPs in large biobanks of indigenous populations, it allows comprehensive reconstruction of male population history.
The study was supported by the Russian Science Foundation grant 14-14-00827 to OB."
That seems like a rather sweeping generalization to draw from the data in terms of R1b, although of course we have to wait and see the paper itself.
If the brother clade of L51 is in the Yamnaya samples we have, why wouldn't it be likely that L51 is west of that in the still largely unsampled areas of western Yamnaya?