November 25, 2009

Sex-biased admixture in the Americas (Stefflova et al. 2009)


PLoS ONE doi:10.1371/journal.pone.0007842

Evaluation of Group Genetic Ancestry of Populations from Philadelphia and Dakar in the Context of Sex-Biased Admixture in the Americas

Klara Stefflova et al.

Abstract

Background
Population history can be reflected in group genetic ancestry, where genomic variation captured by the mitochondrial DNA (mtDNA) and non-recombining portion of the Y chromosome (NRY) can separate female- and male-specific admixture processes. Genetic ancestry may influence genetic association studies due to differences in individual admixture within recently admixed populations like African Americans.

Principal Findings
We evaluated the genetic ancestry of Senegalese as well as European Americans and African Americans from Philadelphia. Senegalese mtDNA consisted of ~12% U haplotypes (U6 and U5b1b haplotypes, common in North Africa) while the NRY haplotypes belonged solely to haplogroup E. In Philadelphia, we observed varying degrees of admixture. While African Americans have 9–10% mtDNAs and ~31% NRYs of European origin, these results are not mirrored in the mtDNA/NRY pools of European Americans: they have less than 7% mtDNAs and less than 2% NRYs from non-European sources. Additionally, there is Additionally, there is less than 2% Native American contribution to Philadelphian African American ancestry and the admixture from combined mtDNA/NRY estimates is consistent with the admixture derived from autosomal genetic data. To further dissect these estimates, we have analyzed our samples in the context of different demographic groups in the Americas.

Conclusions
We found that sex-biased admixture in African-derived populations is present throughout the Americas, with continual influence of European males, while Native American females contribute mainly to populations of the Caribbean and South America. The high non-European female contribution to the pool of European-derived populations is consistently characteristic of Iberian colonization. These data suggest that genomic data correlate well with historical records of colonization in the Americas.

Link

30 comments:

Kepler said...

Very much what countless other reports say througout the Americas.

I wrote about some studies done some time ago in Venezuela:
http://venezuela-europa.blogspot.com/search/label/genetics

Let's say the Iberian males had a lot of fun in Latin America. Pity the native American men.

nae said...

this is just more lies . the native men are still there !

It is just racist and ignorant, alchemy pure bs spun into gold.
the sciences do not know who was here . it is a bald faced lie!

don't believe this crap people.

they do not know who was here see!
nearly 85 pages of interesting reading!
here is just the last 4 pages.

http://forums.about.com/n/pfx/forum.aspx?tsn=403&nav=messages&webtag=ab-archaeology&tid=8304

so don't believe their lies. THEY do not know who was here! Scientists only see what they want to see.

Ricardo Costa de Oliveira said...

The Brazilian results are already known since Gilberto Freyre's sociological interpretation of Brazil. The European mtDNA in Brazil is also considerable and the Native American and African contribution has always been stated by everybody.
What seems original in the article is the frequency of non-European mtDNA in the Philadelphian European American population: 7%.
The ancestral composition of 204 Philadelphian European Americans was estimated to be 93% European (SD: 7%), with a small (although not significant) contribution from Native American (1.6%, SD: 2%) and African (5.5%, SD: 5%) populations (Table S5).
And 9,1% of European mtDNA in the African American population from Philadelphia meaning that somehow African Americans could get European mtDNA in that place, what was not found in the African American population from Brazil, with more European Y DNA than the African Americans from Philadelphia.

Mark Royer said...

Nae, the native mean are indeed still here, but many of them are of mixed ancestry, many with Y Haplogroups R and I. It may not be politically correct, but it is true.

n/a said...
This comment has been removed by the author.
n/a said...

Hicardo: Sorry, no. As much as you seem to desire it, white Americans are not Brazilian-like mongrels.

No sub-Saharan mtDNA was found in the Philadelphia "European American" sample (a substantial fraction of which probably consists of southern Europeans, among whom some sub-Saharan mtDNA would say nothing about America anyway). The only African mtDNA consists of two North African lineages (probably reflecting southern Europeans or Hispanics among the "European American" sample). From these two North African lineages (out of 204 "European American" mtDNAs), the authors somehow managed to derive the 7% "African" maternal estimate.

As for the four "Asian" lineages, none are Amerindian. The N1b is likely an Ashkenazi Jew.

Gioiello said...

Not/Available says: "The N1b is likely an Ashkenazi Jew".

Probably in Philadelphia there are tens of times more Italians than Jews: how can you say surely that those N1b-s are of Jewish extraction? MtDNA N1b is very deeply rooted in Italy, specially in Campania, where many Italians-Americans came from and Italians in the world are tenfold more than Jews. On which numbers is your probability calculation based?

Maju said...

Noticeable to me:

- 2/49 mtDNA U5b1 (4%) among Senegalese but no other West Eurasian lineage, except North African U6.
- 1/150 P(xQ,R) (0.67%) among Philadelphia Euro-creoles

...

Ricardo:

... somehow African Americans could get European mtDNA in that place, what was not found in the African American population from Brazil, with more European Y DNA than the African Americans from Philadelphia.

There were white slaves in North America (Irish notably but not only). Also because of the one-drop-rule, any admixed individual would be automatically classified as black, what implies a slow but persistent gene flow from EA to AA.

The "African" mtDNA in Philadelphia EA is all U6/U5, which is in fact of Eurasian origin (just that also found among the Senegalese controls). U6 is typically North African but also important in Iberia, U5b is West Asian/European and I'd like an explanation of how it ended making up 4% of Dakar's mtDNA.

waggg said...

maju : "U6 is typically North African but also important in Iberia, U5b is West Asian/European and I'd like an explanation of how it ended making up 4% of Dakar's mtDNA."

Maybe during prehistory and the green sahara period, populations from the north moved more southwards and in bigger numbers than first believed.
Mechtoids (cro-magnoids) of north africa might have not all stayed on the north coast too.

After all (not even talking of the R1b) there are tracks of U5 and U6 in subsaharan Africa (besides Senegal), IIRC.

We know that prehistorical population of the north have gone quite south :

http://dienekes.blogspot.com/2008/08/kiffians-and-tenerians-from-sahara.html

It could also explain why the aborigine mtDNA hgs of the canaries are 93 % "west eurasian" (even their U6 is not the typical U6 of north africa).

Ricardo Costa de Oliveira said...

Thanks Maju, yes the "white slaves" or more appropriately the indentured servants making the sociologigal category of the "White Trash"
http://en.wikipedia.org/wiki/White_trash
But I believe in racial diversity and in racial democracy as the impossible utopia and someone wrote in another place that the quintessential European and the "Uber-white" mtDNA is only H1, all others mtDNA haplogroups are mongrels what is a very restricted definition but the world is full of definitions, opinions and adjectives and I respect the social differences and opinions of the minorities of the world. The mtDNA diversity in the American continent was not the problem, but the solution.

All the Best

Maju said...

There were white slaves, not indentured servants, in the British Empire, notably under Cromwell. Remember that the original pretext to enslave someone was religion, not race. Only later on it would evolve to racially based slavery only, roughly at the same time that a racist ideology took over Western thought.

Kepler said...

A haplogroup is a mongrel? Hugh?
What does that mean?

Unless you are like the family of the Austrian Fritz, you have 2 parents, 4 grandparents, 8 greatgrandparents and so on and you are bound to find out theoretically more and more haplogroups.
Pattern: 2 to the n
Even if quite some "cousins" end up begetting children, after just a couple of centuries you are bound to have some ancestors who had the most incredible haplogroups.

I wonder if the people who write those things like n/a, when they found out they had I or whatever as haplogroup they rushed to wear a helmet, they looked themselves on a mirror and started repeating: I AM I haplogroup, I AM I haplogroup.

Ricardo Costa de Oliveira said...

Maju, thanks for the impressive link. I had no idea about the extension of the white slavery
http://www.raceandhistory.com/cgi-bin/forum/webbbs_config.pl/noframes/read/1638
Most interesting to me was that:
"The first Irish slaves were sold to a settlement on the Amazon River In South America in 1612".
When our soldiers exterminated the English from the Amazon they could had captured the Irish slaves there, so if we find any strange Irish DNA in the Amazon it could be perhaps associated to the Irish slaves.

Kepler, let's laugh because haplogroups are eternal, if you have something like M526 in your Y DNA you can be considered an eternal Asian Mongrel, autosomal DNA can be substitued or "washed" in the generations but Y DNA and mtDNA are eternal ! The African genetic Adam and Eve are still here with us, forever

Kepler said...

"Washed away"?
"Eternal"?
Jesus...this guy is a joke.

This "washed away" really sounds like the stories half-literate Latin Americans would tell during Colonial times about "lavar la raza".

So you are a sociologist.

Whatever.

terryt said...

"you have 2 parents, 4 grandparents, 8 greatgrandparents and so on and you are bound to find out theoretically more and more haplogroups.
Pattern: 2 to the n".

But you're still going to have only two haplogroups: one from your mother's mother's etc. mother and one from your father's father's etc. father. What is quite amazing, as Dienekes has shown in several of his posts is that the overall mixture of these male and female haplogroups in a given population coincides to a remarkable degree with the actual admixture. But for an individual the haplogroups only tell your mother's female and your father's male ancestry.

Kepler said...

I know you only have 2 haplogroups. That the overall mixture coincides with the actual admixture of the average person is no wonder, it is to be expected. It does not say anything about the actual admixture of a given individual.
The haplogroup tells you just your mother's mother's mother's (x100) mother...ancestry and your father's father's father's (x100) father's father's ancestry.

There was recently a black man in US who came on TV, no special case, just in the framework of finding out "heritage" for a group of people, and who got the haplogroups of his four grandparents. None was "sub-Saharan". That is atypical, but very possible. Whether you want to be a "pure black" or a "pure white European" or a "pure Asian", if someone 4 generations from you among your ancestors had another haplogroup from "a different race", you are a mongrel. What about 10 generations? What about 50? I am not talking about "we all come from Africa". I am talking about tha last 1500-2000 years...and not on one branch but on several.

And above all: the guy writing about it is a Brazilian. Even if all his grandparents were from Portugal: give me a break!

Ein reinrassiger J1? Por favor!

terryt said...

"Whether you want to be a 'pure black' or a 'pure white European' or a 'pure Asian', if someone 4 generations from you among your ancestors had another haplogroup from 'a different race', you are a mongrel".

And there would be very few people who are not mongrels I'd guess. Besides which, is there any such thing as a 'pure race' anyhow?

Kepler said...

I know, I know. I am just reacting to this "H1" is überwhite or something. At most you can have that chances of someone with H1 having close ancestors with, say, L1 (say, paternal grandmother) are lower than for some others.
A haplogroup tells you just so much about an individual.

Annie Mouse said...

Ricardo Oliviera knows better than most of us the great diversity of his parentage and speaks about it with pride.

Dont misinterprete him.

Annie Mouse said...

Chill Nae

I dont think this paper even looked at Native American people. Just apparently European and apparently African.

Ricardo Costa de Oliveira said...

Thanks Annie
Yes, the self-declared Native American people would have a different proportion. And Brazil is very big, half of South America (far more complex than the other half) and different regions would have different results as well.
Anyway in the American continent the R Y DNA haplogroup has just met again the Central Asian A mtDNA. And Y DNA Haplogroup [IJ] and mtDNA haplogroup H overlaps pretty well in Europe, North Africa, Anatolia and in the Caucasus, where pockets of Caucasian J1 are found in big concentrations, so Y DNA and mtDNA are always meeting each other around the world.

Kepler, I am J1b M365+

Regards

Ricardo

aargiedude said...

Maju, that U5b in West Africa, you can check it out in the U page here (thanks again for pointing out this page to me):

mtdna U phylotree

Search for 16320. It's U5b1b1b (temporary assignment), and it's distinctive mark is 16320, virtually unheard of in other U5b samples. There are several of these in mitosearch, and curiously, they're all from Puerto Rico (maybe the same person?). This very interesting lineage has been known since the early 2000's. I'd gamble that it makes up 1% or 2% of the mtdna of the westernmost section of West Africa. So far, it hasn't been observed in North African U5.

Note that the immediate neighbors to this lineage in the phylotree diagram are restricted to Finland.

Maju said...

I'll follow you on that, Argiedude.

Dakar anyhow has a history of being a European colonial outpost, first Portuguese and the French. It can well have an odd founder effect from some promiscuous slave trader or missionary (and all were) and it would have caused this kind of micro founder effect.

Maybe the same type of reason as for the odd K(xR,T) of Cape Verde. So it may well be limited to the Dakar area.

Maju said...

Note that the immediate neighbors to this lineage in the phylotree diagram are restricted to Finland.

There was an obscure, brief and discontinued Norman colonist/crusader episode (interrupted by the Hundred Years' War) in that area, with center in the disputed Canary Islands but possibly with some presence in West African coasts too.

I say because Normans are the closest ethnicity to Finland I can think of operating in that area historically.

Maju said...

Self-correction:

It can well have an odd founder effect from some promiscuous slave trader or missionary...

Silly me! We're talking mtDNA...

It makes no sense that way: this kind of founder effect is almost impossible to attribute to a woman the way I did.

waggg said...

@ aargiedude :

"Note that the immediate neighbors to this lineage in the phylotree diagram are restricted to Finland."

Another common point between north africa/sahara and Finland is the presence of mtDNA haplogroup V (mtDNA hg V is also found in Tuaregs).

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1199377/?tool=pmcentrez

"Seven of the new sequences (one Berber from Algeria, two Italian, one Spanish, and three Saami) clustered into U5b1b, the subclade encompassing the Yakut and FULBE mtDNAs."

"Furthermore, their frequency patterns and ages resemble those reported for haplogroup V (Torroni et al. 2001a)— which, similar to U5b1b, is extremely common only in the Saami (together, U5b1b and V encompass almost 90% of the Saami mtDNAs) (Torroni et al. 1996; Tambets et al. 2004)"

Maju said...

Not in Tuaregs (who are highly H1 in fact) but in Kabylians and other Eastern Algerian Berbers, as well as in Tunisia (all from memory). Not all Algerian Berbers are Tuareg, in fact most are not. Tuaregs are a rather special population within Berbers anyhow.

Whatever the case these African/Europe relations could have a common West Asian origin, from Neolithic times maybe. I really do not see much Finland-Senegal interaction in the past. Anyhow, just for the record, Senegal and Sweden (not Finland though) were once at the very edges of Megalithic diffusion too.

waggg said...

@ Maju : "Not in Tuaregs"

Well, at least in Lybian Tuaregs.

http://dienekes.blogspot.com/2009/05/mtdna-of-libyan-tuaregs.html

"Whatever the case these African/Europe relations could have a common West Asian origin"

You exclude a presence of mtDNA V in European paleolithic populations ?

"I really do not see much Finland-Senegal interaction in the past"

Unless we're talking of a time when human populations were not distributed the way they are now.
When Finland was under the ice for instance, when the ancestors of the Saamis were not living there yet, before it was colonized.

I know the northern Europe was inhabited earlier than thought, but still.

http://www.sr.se/cgi-bin/International/nyhetssidor/artikel.asp?ProgramID=2054&format=1&artikel=3270787

mtDNA hg V is mostly (almost exclusively excepted for north Africa) located in Europe I believe, am I wrong ?

Don't you think it makes sense to believe it's related to the Franco-Cantabrian glacial refuge ? (populations that would be at least mtDNA H1, H3, U5, V).

If mtDNA H is found to be neolithic in Europe, V and U5 (and U6 maybe, right ?(high diversity in north Portugal, IIRC)) are still good candidates for remains of population come from Europe in ancient time.

Maju said...

You exclude a presence of mtDNA V in European paleolithic populations? -

My bad. I was thinking of U5b in particular...

But both lineages could have crossed the strait at any moment, for example at the Oranian genesis, which in my opinion should have an Iberian Gravetto-Solutrean ultimate origin.

But while this may explain Berber H and V (and maybe Iberian U6 too, as backflow), I find hard to explain this way U5b as far south as Senegal and with no apparent North African connection.

But V was apparently found among Taforalt remains, so I guess it has an old presence in Europe and North Africa and must have spread with H. But how much U5b is there in all North Africa?

Don't you think it makes sense to believe it's related to the Franco-Cantabrian glacial refuge ? (populations that would be at least mtDNA H1, H3, U5, V).

Makes sense (in a loose sense). However I insist that I'm not aware of U5b in North Africa, so it's hard to explain how it arrived to Senegal.

Maju said...

@Argiedude:

Waag just called my attention back to this discussion, as the U5b1b1 haplogroup arose in another thread at Leherensuge.

The case is that I don't understand why U5b1b1 is organized the way it is in Phylotree, while the reference paper distributes it in a very different way (with the name of U5b1b), forming as four basal sublineages:

1. Italian
2. Ibero-Italian
3. Saami-Yakut
4. Berber-Senegalese

The lineage you mention would hence be a sublineage of the Berber-Senegalese subclade, and SW Europe (Italy maybe) would be the most likely homeland for the haplogroup as a a whole.

Mystery solved?