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torzio
07-05-20, 06:41
Historical genetic links among similar populations can be difficult to establish. Identity by descent (IBD) analyses find genomic blocks that represent direct genealogical relationships among individuals. However, this method has rarely been applied to ancient genomes because IBD stretches are progressively fragmented by recombination and thus not recognizable after few tens of generations. To explore such genealogical relationships, we estimated long IBD blocks among modern Europeans, generating networks to uncover the genetic structures. We found that Basques, Sardinians, Icelanders and Orcadians form, each of them, highly intraconnected sub-clusters in a European network

https://www.nature.com/articles/s41598-020-64007-2

Palermo Trapani
07-05-20, 19:19
Historical genetic links among similar populations can be difficult to establish. Identity by descent (IBD) analyses find genomic blocks that represent direct genealogical relationships among individuals. However, this method has rarely been applied to ancient genomes because IBD stretches are progressively fragmented by recombination and thus not recognizable after few tens of generations. To explore such genealogical relationships, we estimated long IBD blocks among modern Europeans, generating networks to uncover the genetic structures. We found that Basques, Sardinians, Icelanders and Orcadians form, each of them, highly intraconnected sub-clusters in a European network

https://www.nature.com/articles/s41598-020-64007-2


Torzio: Thanks for the link to this paper. I previewed it and decided to download it and print it out and keep a hard copy with other papers I have here with me during COVID-19 situation. Interesting paper.

Angela
07-05-20, 19:53
That's to be expected in such isolated populations.

Much the same was shown quite a long time ago by Ralph and Coop.
https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.1001555

This is also to be expected...I don't think there's been that much change in Southern Europe since the Medieval period, with the exception of Italy because of the mass migration from south to north starting in the fifties. Well, there's been a lot of movement from Andalusia to Barcelona as well, from what I've heard.

"Moreover, using ancient DNA technology we sequenced a Late Medieval individual (Barcelona, Spain) to high genomic coverage and identified IBD blocks shared between her and modern Europeans. The Medieval IBD blocks are statistically overrepresented only in modern Spaniards, which is the geographically closest population. "

What was a little unusual was this:

"We also exposed individual genealogical links -such as the connection between one Basque and one Icelandic individual- that cannot be uncovered with other, widely used population genetics methods such as PCA or ADMIXTURE."

Basques are great fisherman, tho...fishing all along the north Atlantic coast.

This a promising new tool, however. We might be able to pick up influence from the late first millennium migrations on modern populations, which would be better than just relying on Admixture just showing us genetic similarity. MTA claims to be able to do it, but I doubt their method has the sophistication and accuracy of this tool.