R1b1b2 tree revisited

A few days ago a reader made me notice a meaningful error in my previous version of the West Eurasian R1b structure. The tree was correct but I had an error in the DYS loci numbers that caused me some confusion when comparing with other data, like that at the valuable Ht35 project (FTDNA).

So I have been rethinking all the issue from scratch and have just finished producing a new version of the same tree, where haplogroup and haplotype structure are blended as far as my knowledge reaches.

Click to expand

As is mentioned in the picture, the haplotypes are taken from Alonso 2005, paper that may be somewhat limited in some aspects, like the restrictive choice of DYS markers but is anyhow the wider academic survey I know of R1b in West Eurasia. More specifically they are taken from his selection of the most common (above 2%) haplotypes, as shown in the distribution map (two were duplicated and hence irrelevant, and another one only frequent in Iceland has also been ignored for convenience). As R1b1b1 is only found in Central Asia, R1b* is extremely rare outside Africa (Egypt and south of the Sahara, where it surely makes up a distinct subhaplogroup, whose defining SNPs have not been found yet) and the minor haplogroups R1b1a and R1b1c are practically limited to Sardinia and Lebanon, not sampled by Alonso, this is in practical terms the same as talking of haplogroup R1b1b2.

In any case, I have been checking that the haplotypes correspond with haplogroup-described ones and I am quite sure that the above haplogroup sets (yellow boxes with orange legend) are very much correct. All haplotypes seem to correspond to only one of the R1b1b2 structural layers, excepting the modal (most common) 14-24-11-13-13, which in fact belongs to two of them: R1b1b2a1* and R1b1b2a1a. This and the haplotype tree structure imply that all SNPs at the root of R1b1b2a1a (only L11 is mentioned but there are three others known) happened within this haplotype, though there may be some differences in other loci, which I have not bothered researching yet. What is clear is that there are some mutations (haplogroup-defining SNPs at least) in this most common (modal) haplotype and hence I had to duplicate this haplotype to show it with and without the L11 (and the other three) SNP mutations that define haplogroup R1b1b2a1a (I did so anyhow with a colored line, so the difference is easy to spot).

The four most common haplotypes by local frequencies are shown in bold and larger type and with the same color as in Alonso's map, for easier identification. It is noticeable that all haplotypes have an either West Asian or European distribution (once we exclude the somewhat mixed Croatian pool and maybe minor erratics) excepting two: the "modal" 14-24-11-13-13 (in red) and what I call the "Anatolian modal" 14-24-11-13-12 (in cyan blue). However the latter is rare in Europe except maybe in Croatia and Italy and the former is much more common almost anywhere in Europe than in Asia. The dividing line between West Asia and Europe (mostly West Europe) is therefore around the R1b1b2a1 node.

Geographic structure

R1b1b2* - Its only major haplotype is found only in West Asia (rare) and among Berbers (more frequent).

R1b1b2a* - It is found almost only in West Asia, with some offshots into SE Europe and even at very low frequencies, Central Europe, Iberia and Ireland. Excepting Croatia all its presence in Europe seems to belong to the "Anatolian modal" clade. It is not found among Berbers though.

R1b1b2a1* - It is found almost exclusively in Europe. The only exception are some amounts of the modal haplotype, that is also found in West Asia and among Berbers, though I am not sure if this belongs to this haplogroup or the derived R1b1b2a1a. Apart of the modal haplotype (that is also the root), it has two branches, both rather widespread in their root haplotypes, however they seem more frequent towards Central/Northern Europe. The most common of the two (root at 14-23-11-13-13, color: purple) has highest frequencies in the Low Countries of all places, while the less important one seems to have its highest frequencies in Wales, with some Atlantic distribution if anything.

R1b1b2a1a - This is the most common R1b in Europe, being quite obviously rare elsewhere, except among Berbers. As such it shows a relatively wide array of more relevant (above 2% in Alonso's sample) haplotypes. Surely the most important haplotype is the "modal" one (I'd say from other data that about 80% or 90% of this haplotype belongs to this haplogroup), which is widely distributed. Besides, it has three branches, one of which is quite important too (root at 14-24-10-13-13, color: black) and is widely distributed as well, with a highest frequency in Scotland (though also common in other populations, including Berbers but not West Asians). The other two are less important and show certain Atlantic tendency maybe, with lower tier haplotypes being rather common among Berbers.

And this is what I can tell about this important haplogroup by the moment.
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