Category Archives: Admixture - Page 8

Another Reference Admixture Set

From my Reference 3 dataset, I excluded the following populations for this set of admixture runs:

  • Biaka Pygmy
  • Mbuti Pymy
  • San
  • Bantu South Africa
  • Hadza
  • Chukchis
  • Koryaks
  • Colombian
  • Dominican
  • Ecuadorian
  • Karitiana
  • Maya
  • Mexican
  • Pima
  • Puerto Rican
  • Surui
  • East Greenlanders
  • West Greenlanders
  • Australian aboriginals
  • Melanesian
  • Papuan

The San and Pygmy were removed since they are very distinct and take up clusters and the South African Bantu because they have significant admixture from the San. The Hadza seem to be a unique population too.

The Chukchis and Koryaks are Beringian populations from the Russian Far East which separate from the Siberian and Turco-Mongol groups at higher K's.

I also excluded all the American populations because our focus is on South Asia and environs. I have a few participants with Amerindian ancestry and I can always run their analyses with the full reference 3.

The Papuans and Melanesians take up 2 ancestral components in admixture at times and since admixture works well only for about K<12 or so, those are precious. Also, I originally thought that South Asians (specifically the ASI) might have some affinity with Papuans but that hasn't borne out. In addition to removing these populations, I reduced the number of samples of various groups (except South Asian ones) to 25 individuals so that admixture won't rely too heavily on any of those large groups (like the 161 Yoruba). In selecting individuals from these populations, I chose those closest to the median in terms of their admixture results. The admixture results of this dataset are in a spreadsheet as usual and the bar chart is below.

K=12 is the one with the lowest cross-validation error.

I am going to post another series of admixture runs tomorrow and then you guys can let me know which specific runs you like so we can switch to those for the project participants.

Reference 3 Admixture Error Estimation

Since no one paid any attention to the error estimation results for reference I admixture, I am back with the standard error and bias estimates for reference 3 admixture.

So I ran the default 200 bootstrap replicates to measure standard error in our Reference 3 K=11 admixture. Spreadsheet with population level admixture results is here and participant results are here.

Here are some statistics for the standard error estimates:

Min. 1st Qu. Median Mean 3rd Qu. Max.
C1 S Asian 0 0.127 0.9848 0.7505 1.2216 1.6833
C2 Onge 0 0.2074 0.56 0.5404 0.8268 1.6914
C3 E Asian 0 0.2013 0.6123 0.6751 1.136 1.9961
C4 SW Asian 0 0.0874 1.1462 0.9246 1.5347 2.1008
C5 Euro 0 0.042 1.3034 0.9684 1.6582 2.3861
C6 Siberian 0 0.2054 0.6566 0.6712 1.0969 2.0099
C7 W African 0 0 0.01905 0.38847 0.75713 2.1588
C8 Papuan 0 0.1936 0.375 0.3648 0.5308 1.9627
C9 American 0 0.1461 0.3958 0.4646 0.6342 2.0831
C10 San/Pygmy 0 0 0.0708 0.2514 0.4471 2.0991
C11 E African 0 0 0.1235 0.3969 0.7315 1.9318

You can see the mean value of the standard errors per population and realize how many are over 1% (marked in red).

As the average error for the Onge component among South Asian populations is a little higher than 1%, the standard error on the ASI (Ancestral South Indian) computation here is about 1.4-1.5% just from admixture. The regression error is in addition to that.

And statistics for bias estimates:

Min. 1st Qu. Median Mean 3rd Qu. Max.
C1 -0.9069 -0.28408 -0.0349 -0.12196 0.01158 0.5856
C2 -0.7701 0 0.04005 0.03847 0.153 0.5703
C3 -0.5778 -0.0888 0.01645 0.02105 0.13737 0.6127
C4 -0.7701 -0.1657 0 -0.06692 0.01298 0.745
C5 -1.2917 -0.247675 0 -0.113631 0.008975 0.6763
C6 -0.7921 -0.0856 0.0129 0.009492 0.1198 0.6464
C7 -0.5745 0 0 -0.02173 0.0016 0.3426
C8 -0.1842 0.05328 0.13175 0.1377 0.21247 0.4712
C9 -0.4202 0.0096 0.0811 0.0915 0.1682 0.5129
C10 -0.4596 0 0.0002 0.003271 0.023425 0.3447
C11 -0.5766 0 0.0018 0.02276 0.05758 0.6346

You can also see the average value of the bias in each ancestral component for each population.

Admixture (Ref3 K=11) HRP0091-HRP0100

Here's my first admixture run using Reference 3 for Harappa participants with FTDNA data.

You can see the participant results in a spreadsheet as well as their ethnic breakdowns and the reference population results.

Here's our bar chart and table. Remember you can click on the legend or the table headers to sort.

If the above interactive charts are not working, here's a static bar graph.

Since this is my first analysis of FTDNA data, I asked HRP0006 to provide me with his FTDNA results (HRP0093) too so they can be compared. Let's see how that turned out.

HRP0006 HRP0093
C1 S Asian 49.31% 49.06%
C2 Onge 14.13% 13.70%
C3 E Asian 1.12% 0.00%
C4 SW Asian 14.65% 12.52%
C5 European 18.88% 22.44%
C6 Siberian 0.00% 0.78%
C7 W African 0.00% 0.00%
C8 Papuan 0.54% 0.01%
C9 American 1.35% 1.48%
C10 San/Pygmy 0.00% 0.00%
C11 E African 0.00% 0.00%

There are differences of up to 3% but generally the results are reasonably close.

HRP0095 and HRP0100 thought they had possible South Asian ancestry. That seems fairly unlikely at least in the last few generations since their Onge component is zero or very low.

West, Central, South & Southeast Asian Admixture

Another set of admixture runs. This one uses the South Asian, Middle Eastern, Caucasian, Central Asian, Southeast Asian and Oceanian samples from Reference 3.

Basically I consider these to be our target populations. The idea is to build out from here by adding a few samples from other populations to make the results better.

Right now, the absence of African, European, East Asian and Siberian populations makes some of the other populations substitute for them. For example, Siddi works as African substitute while Aonaga works as East Asian substitute.

Here are the admixture results. You can choose the number of ancestral components, K, from the dropdown below.

I find K=11 and K=14 to be the most interesting. They have the two lowest cross-validation errors too.

Reference I Admixture Errors

I am have thinking about error estimation for Admixture results for some time since I have heard a lot of arguments about how even 0.1% result is significant. I was skeptical of that and have rounded off my admixture run results to the nearest percent.

There was a memory leak issue in the bootstrapping code for admixture which crashed it every time I tried running it. I emailed David Alexander and he fixed it in version 1.12.

So I ran the default 200 bootstrap replicates to measure standard error in our old Reference I K=12 admixture. Spreadsheet with population level results is here and participant results are here.

Here are some statistics for the standard error estimates:

Min. 1st Qu. Median Mean 3rd Qu. Max.
C1 S Asian 0.00% 0.02% 0.33% 0.52% 0.96% 1.93%
C2 Blch/Cauc 0.00% 0.00% 1.02% 0.79% 1.45% 2.63%
C3 Kalash 0.00% 0.01% 0.40% 0.50% 0.99% 3.76%
C4 SE Asian 0.00% 0.09% 0.37% 0.60% 1.27% 1.92%
C5 SW Asian 0.00% 0.00% 0.60% 0.66% 1.28% 2.90%
C6 Euro 0.00% 0.00% 0.35% 0.56% 1.12% 1.82%
C7 Papuan 0.00% 0.07% 0.22% 0.23% 0.36% 1.08%
C8 NE Asian 0.00% 0.07% 0.36% 0.67% 1.36% 2.45%
C9 Siberian 0.00% 0.08% 0.37% 0.51% 0.82% 2.29%
C10 E Bantu 0.00% 0.00% 0.00% 0.35% 0.72% 1.93%
C11W Afr 0.00% 0.00% 0.00% 0.28% 0.50% 1.51%
C12 E Afr 0.00% 0.00% 0.05% 0.31% 0.60% 1.79%

You can see the mean value of the standard errors per population and realize how many are over 1% (marked in red).

And statistics for bias estimates:

Min. 1st Qu. Median Mean 3rd Qu. Max.
C1 S Asian -1.104% -0.031% 0.000% -0.024% 0.075% 1.026%
C2 Blch/Cauc -0.835% -0.280% -0.009% -0.133% 0.000% 1.049%
C3 Kalash -1.575% 0.000% 0.020% 0.076% 0.147% 0.615%
C4 SE Asian -0.629% -0.021% 0.011% 0.018% 0.087% 0.478%
C5 SW Asian -0.691% -0.094% 0.000% -0.020% 0.035% 0.613%
C6 Euro -0.572% -0.086% 0.000% -0.039% 0.004% 0.468%
C7 Papuan -0.171% 0.008% 0.059% 0.070% 0.120% 0.312%
C8 NE Asian -0.739% 0.000% 0.016% 0.034% 0.107% 0.679%
C9 Siberian -1.044% 0.000% 0.015% 0.035% 0.103% 0.692%
C10 E Bantu -0.412% 0.000% 0.000% -0.007% 0.001% 0.370%
C11 W Afr -0.261% 0.000% 0.000% 0.009% 0.005% 0.304%
C12 E Afr -0.635% 0.000% 0.000% -0.017% 0.010% 0.405%

You can also see the average value of the bias in each ancestral component for each population.

Since the bias is lower than the standard error and distributed around zero, if a large number of samples of a population group have some small percentage of an ancestral component, the likelihood of that not being noise is higher.

Reference 3F(iltered) Admixture

I removed all American populations and San and Pygmy (i.e., South and Central African) from Reference 3 for a better focus on our target populations.

Here are the admixture results. You can choose the number of ancestral components, K, from the dropdown below.

K=13, 14, 15 (in that order) have the lowest cross-validation error.

There's a bunch of interesting results in there. For example, the split into northern and southern European, and the split of Siberian into Siberian and Russian Far East (or Bering Strait). However, the Onge component as a proxy of the ASI does not appear. Also, we don't get much breakdown of the South Asian populations as we would like.

Ref3 + Harappa Maps

More maps from The Jatt Gene using the Reference 3 and Harappa participants K=11 admixture results.

C1 South Asian Isopleth

C2 Onge Isopleth

C1 South Asian Chloropleth at state/province level

C2 Onge Chloropleth

As usual, Simranjit has more maps on his blog.

Harappa Ref3 Admixture Dendrograms

Now that we have the admixture results for project participants using Reference 3, let's take a look at a tree based on Euclidean distance of the admixture proportions for each participant.

Compare it to the earlier one with reference 1 admixture results.

And here is a dendrogram combining the average reference population results with the Harappa participants.

Harappa (1-90) K=11 Admixture Ref3

Here's my first admixture run using Reference 3 for Harappa participants. Since K=11 was the run with the Onge-ASI connection, I ran admixture at K=11 with all the 90 Harappa participants.

You can see the participant results in a spreadsheet as well as their ethnic breakdowns and the reference population results.

Here's our bar chart and table. Remember you can click on the legend or the table headers to sort.

Using the comparison between the Onge component here and Reich et al's Ancestral South Indian one, I get the following linear regression.

The correlation is 0.9949 which is probably as high as it can get. So let's calculate the ASI percentage for all the Harappa participants.

Note that I didn't calculate the ASI percentage for those who had a really low Onge component since the linear regression above would not be valid outside the range we have in our original data.

You can see the percentages in a spreadsheet too.

Let's compare with the Dodecad ANI-ASI results. I have 22.5% ASI here while it was 20.6% in the Dodecad analysis. Overall, it seems like my technique results in about 2% more ASI than Dodecad's, with a few exceptions: Like Razib who jumps from 34.3% to 43.3% (averaging his parents who are very close).

Reference 3 K=11 Admixture Dendrogram

Laredo asked:

Is it possible for you to create an unrooted similarity tree of all the populations in your “Reference 3″ dataset?

So here's a dendrogram of the average K=11 admixture results for the reference 3 populations.