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View Full Version : Pop. resequencing of European mtDNA highlights sex-bias in Bronze Age demo. expansion



I1a3_Young
21-09-17, 19:05
https://www.nature.com/articles/s41598-017-11307-9



Chiara Batini (https://www.nature.com/articles/s41598-017-11307-9#auth-1),
Pille Hallast (https://www.nature.com/articles/s41598-017-11307-9#auth-2),
Åshild J. Vågene (https://www.nature.com/articles/s41598-017-11307-9#auth-3),
Daniel Zadik (https://www.nature.com/articles/s41598-017-11307-9#auth-4),
Heidi A. Eriksen (https://www.nature.com/articles/s41598-017-11307-9#auth-5),
Horolma Pamjav (https://www.nature.com/articles/s41598-017-11307-9#auth-6),
Antti Sajantila (https://www.nature.com/articles/s41598-017-11307-9#auth-7),
Jon H. Wetton (https://www.nature.com/articles/s41598-017-11307-9#auth-8) &
Mark A. Jobling (https://www.nature.com/articles/s41598-017-11307-9#auth-9)




Here we have undertaken a population-based resequencing of complete mitochondrial genomes in Europe and the Middle East, in 340 samples from 17 populations for which Y-chromosome sequence data are also available. Demographic reconstructions show no signal of Bronze Age expansion, but evidence of Paleolithic expansions in all populations except the Saami, and with an absence of detectable geographical pattern. In agreement with previous inference from modern and ancient DNA data, the unbiased comparison between the mtDNA and Y-chromosome population datasets emphasizes the sex-biased nature of recent demographic transitions in Europe.


Our data are consistent with ancient DNA data14 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR14),15 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR15),16 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR16) in supporting sex-biased processes in recent European demographic changes: patterns of modern mtDNA diversity show no signal of the Bronze Age expansion, while much of the modern European MSY diversity has been shaped by this process12 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR12). However, the modern data differ in showing no clear signal of the Neolithic transition that has been highlighted in ancient mitochondrial and autosomal data5 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR5),16 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR16). This could be due to drift, which is important in shaping the observed patterns of diversity in uniparental markers, and also sampling effects.

Here's the most significant statement that I noticed:

These findings contrast with phylogeographic studies based on mitochondrial DNA (mtDNA), which have been interpreted as supporting expansions from glacial refugia.

Angela
21-09-17, 19:15
"However, the modern data differ in showing no clear signal of the Neolithic transition that has been highlighted in ancient mitochondrial and autosomal data5 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR5),16 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR16). This could be due to drift, which is important in shaping the observed patterns of diversity in uniparental markers, and also sampling effects."




I haven't read the paper yet, so I may be all wrong, but if their method misses the Neolithic transition because of these issues, who says they're not missing the Bronze Age one?

I1a3_Young
21-09-17, 19:29
I haven't read the paper yet, so I may be all wrong, but if their method misses the Neolithic transition because of these issues, who says they're not missing the Bronze Age one?

Perhaps due to the time difference. Older changes are harder to detect and more likely to be obscured by drift.

Promenade
21-09-17, 20:59
Some more evidence of a Indo European invasion of India.

"The most ancient mtDNA expansions we detect, dating close to the early peopling of Eurasia (40–50 KYA), are in the Near and Middle East. This difference in timing of European female and male lineage expansions is mirrored in the Indian subcontinent, where a recent analysis33 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR33) shows that mtDNA expansions reflect processes in the pre-Holocene era, while MSY expansions are mostly in the last 10 KYA, with marked male-driven spread from Central Asia during the Bronze Age."

I know people doubt just how much of an "invasion" the shift to steppe ancestry included in Northern Europe, but considering the population density of India coupled with sex bias it makes sense in my mind that it was not just a simple migration, at least in South Asia.


Also East Asian components found in the Saami

"Population-based genome-wide SNP analysis37 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR37) and whole-genome sequencing of a single individual38 (https://www.nature.com/articles/s41598-017-11307-9#ref-CR38) also show the Saami to be genetically differentiated compared to Europeans, and to carry East Asian ancestry components."