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tirsdag 28. august 2012

Distinctive haplotypes in Saamis and Finns

I want to return to the differences one sees between donors and receivers. The sharp observer would probably notice the difference between the donation and receivers between f.ex Finns and the Chuvash or even in general between Saamis and Finns and other populations. The Finns dont use much Chuvash chromosomes to paint there chromosomes but Chuvash use on the other hand more Finn chromosomes to paint their chromosomes.

In the "newick" format it could be written as C(F1,F2). It has nothing to do about ancestral to who but is a tree representing three current populations. Where C vs F1,F2 coalesce at a time t1 and F1,F2 coalesce at a time t2. As we know it is correct to assume that F1,F2 coalesce at an later time than vs the C and probably F1,F2 similar coalesce time to C.

If we then assume that F1,F2 have have very distinctive haplotypes the painting of F1,F2 will ignore copying chunkcounts from C as it can find closer haplotypes internally, but C on the other hand is equally distant to F1,F2 will copy smaller chunkcounts from both of these. This will result in a symmetrical chunkcount heatmap.

ID    C    F1    F2
C     0    0.5    0.5
F1   0     0      1
F2   0     1      0

This can be seen very clearly as an extreme case with the ancient gotlanders vs modern populations, where the modern populations copy very little chunks from the ancient gotlander but the ancient gotlander copy much chunks from the modern populations as there a no other to copy from. If we had than one ancient gotlanders the picture would of course change. It would probably also be similar if we included a single San individual from Africa.

So asymmetrical donation-receiving for a population can be explained by distinct haplotypes for that population vs other populations.

(Thanks to the authors of Finestructure for their explanations and patience!)

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