Friday, August 10, 2012

fastIBD analysis of East/Central Eurasians and select West Eurasians


Individuals from the following populations have been included in this analysis:
Philippines_D Turkish_D Iranian_D Russian_D Finnish_D Turkish_Cypriot_D Ukrainian_D Belorussian_D Chinese_D Korean_D Japanese_D Tatar_Various_D Kazakh_D Szekler_D Hungarian_D Estonian_D Azeri_D Udmurt_D Mixed_Turkic_D 
These were analyzed in a context of a complete set of Central/East Eurasian populations; West Eurasian populations included were mostly Uralic and Turkic speaking groups, and a few others (such as East Slavs or Iranians).

A few quick points:
  • fastIBD was run with default parameters over a dataset of 627 individuals/255020 SNPs
  • fastIBD identifies segments of relatively recent origin that are shared by individuals. These results should not be construed as measures of overall genetic similarity or origins. Rather, they suggest which populations have exchanged genes in the relative recent past.
With that said, you can get:
  • Spreadsheet of numeric results, showing sharing (in centi-Morgans, cM)
  • Population-level graphical results, showing an ordering of other populations based on mean IBD sharing.
IBD sharing was assessed only for populations with 5+ individuals.

The following heat map allows for a quick appraisal of populations sharing an excess of IBD sharing (read row-by-row)

And, a few visualizations of mean IBD sharing:

Notice high levels of within-population IBD sharing for Finns, consistent with a population that experienced expansion from a small number of founders (small ancestral population size).
Compare with Turks, who are a much more diverse population.
These two plots (you can check the spreadsheet for exact numbers) indicate different sources for the East Eurasian element in Turks and Finns. 

The top eastern populations for Turks are: Turkmen, Chuvash, Uzbek, Uygur, all of which are Turkic speakers, followed by Hazara, Yukagir, and Selkup.  For Finns, there is high degree of sharing with various Siberian groups of different languages, including Uralic Selkups (16.4cM) and Nganassan (9.6cM). Turks share less with these Uralic speakers (6.4 and 2.8cM respectively). So, these are strong hints of common shared ancestry within the Turkic and Uralic language families.

The Chuvash population is also quite interesting, as it shares more with Selkup and Nganassan, contrasting with other Turkic speakers. This makes excellent sense, and is in agreement with other recent findings:
Results from this study maintain that the Chuvash are not related to Altaic or Mongolian populations along their maternal line, thus supporting the “Elite” hypothesis that their language was imposed by a conquering group —leaving Chuvash mtDNA largely of Eurasian origin. Their maternal markers appear to most closely resemble Finno-Ugric speakers rather than Turkic speakers.
Sources of data are listed at the bottom left of this blog.

8 comments:

  1. The top eastern populations for Turks are: Turkmen, Chuvash, Uzbek, Uygur, all of which are Turkic speakers, followed by Hazara, Yukagir, and Selkup. For Finns, there is high degree of sharing with various Siberian groups of different languages, including Uralic Selkups (16.4cM) and Nganassan (9.6cM). Turks share less with these Uralic speakers (6.4 and 2.8cM respectively). So, these are strong hints of common shared ancestry within the Turkic and Uralic language families.

    The progression of the IBD sharing of Turks from Turkmens to Uyghur you enumerated and the amounts (shown in centi-Morgans) of Turks' IBD sharing with those populations have much more to do with the progression in those populations from the most Caucasoid to the most Mongoloid and the pre-historical southern Caucasoid connections between West Asia and Central Asia than with the Turkicness of those populations, as is clear from the presence of the same progression and in similar centi-Morgan values in Iranians and Turkish Cypriots, who both seem to have almost no Turkic origin according to ADMIXTURE analyses. Wish you included more non-Turkic populations from West Asia (especially from its northern part) in this analysis. That way it would be easier to make an estimation about the real effects of Turkic ancestry on IBD sharing.

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  2. Many thanks for this excellent analysis, I hope that you go on with a larger European population set.

    A question. I see that on the matrix there is on upper left side a stronger connection between Russians and Finns. Can you say the gene flow direction, is it from Finns to Russians or conversely?

    I made also a short statistics about selected Asian IBD-sharing for these few Europeans included to the data. All East and Northern Asian populations are included as far as I know them. No Central Asians are included. What makes this interesting is that IBS and different component statistics show stronger Asian influence among Finns compared to used East European populations, except North Russians.


    Ukrainian_D 3,24
    Ukranians_Y 3,251428571
    Belorussian 3,322857143
    Russian_D 3,908571429
    FIN30 4,231428571
    Mordovians_Y 4,274285714
    Finnish_D 4,322857143
    Russian 4,602857143

    If we took only known Siberians the statistics look as following

    Ukrainian_D 5,1
    Ukranians_Y 5,15
    Belorussian 5,433333333
    Russian_D 7,083333333
    Mordovians_Y 8,05
    FIN30 8,916666667
    Finnish_D 9,316666667
    Russian 9,733333333

    ReplyDelete
  3. A question. I see that on the matrix there is on upper left side a stronger connection between Russians and Finns. Can you say the gene flow direction, is it from Finns to Russians or conversely?

    The most obvious source is the Finnic substratum absorbed by eastern Slavs as they expanded during medieval times.

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  4. What is you opinion about the gene flow between North Europeans and Turks, between North Europeans and Iranians.

    As you have stated, I think also that the question of gene flow directions is still poorly understood. It is the base of understanding old migration, neolithic and paleolithic times. I don't think that gene flows are always easily determined, but I do think that we can do it much better than now.

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  5. Direction of gene flow is a very hard nut to crack. In one of the talks here, someone is making an effort to crack it; I'll wait for the paper to comment, but the fact that he places human origins in South Africa doesn't look very promising to me:

    http://gcbias.org/2012/05/29/bapg-at-ucdavis-podcasts/

    The main problem is that it is difficult to distinguish between admixed and ancestral populations. An admixed population may appear more genetically diverse than its parental populations, and if enough time has transpired (erasing signals of LD), then one might posit a migration out of the admixed population that produced its parental pottlenecks through genetic diversity reducing "bottlenecks".

    There's only so much one can do with modern DNA; it is ultimately ancient DNA -wherever it can be preserved- that can complete our picture of population dispersals in a very convincing way.

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  6. Turkmens and Chuvashs speak Oghur/Oghuz branch of Turkic languages. Uzbeks and Uygurs speak Karluk branch. Both of these started to spread from homeland earlier than Qipchak branch.
    Oghuz Turks migrated both southern and northern routes (around Caspian sea) reaching East Europe and Balkans. While Karluks chose Southern route and ended up as far as Afghanistan.

    ReplyDelete
  7. Turkmens and Chuvashs speak Oghur/Oghuz branch of Turkic languages.

    The Oghuz branch (the branch of Turkmens' language) has nothing to do with the Oghur branch (the branch of Chuvashs' language). The Oghuz branch is a Common Turkic branch, and Common Turkic includes the Qipchaq, Qarluq (Uyghuric) and Siberian (including Yakut) branches as well. In contrast, the Oghur branch is a Turkic branch that is separate from the Common Turkic branch. (Proto-Oghur diverged from Proto-Common Turkic at an early date). In fact, Common Turkic and Oghur are the primary divisions of the Turkic language family.

    Both of these started to spread from homeland earlier than Qipchak branch.

    There does not seem to be enough information to pinpoint the start of their spread from the Common Turkic homeland. Complicating the matter further, 1000 years ago Common Turkic varieties were so close to each other as to be at most dialects of a single Common Turkic language, also there was much more transitivity and nestedness between them, thus it was very hard to draw boundaries between them.

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  8. Contrasts

    In your view, what Dodecad Ancestry Project run show the best ancient admixture compared to this run, that shows recent exchange?

    ReplyDelete