February 10, 2011

Swedish population structure (Salmela et al. 2011)

From the paper:
In our earlier study [4], we saw that North European populations exhibited differing amounts of IBS similarity to East Asians so that Finns, especially Eastern Finns, were the most similar. Now we have observed the same phenomenon - though in a smaller degree - within Sweden, where Norrland showed the most of East Asian similarity and Götaland the least. This is consistent with earlier Y-chromosomal studies [13]. In strong contrast, however, neither Norrland nor Eastern Finns showed any increase in similarity to the Vologda Russians, and a similar lack of affinity between Finns and Russians can also be seen in separate datasets [6], [13]. Thus, if the current references are representative of Russians in this respect, the observed affinity to Eastern Asia would not be mediated by contacts with Russians but could reflect an ancient eastern influence predating the arrival of Slavic populations to Northeastern Europe in the end of the first millennium [23]. It remains unclear whether the eastern affinity observed in Sweden would date back to the same era, or rather reflect the amount of later Finnish contacts to the area.


PLoS ONE 6(2): e16747. doi:10.1371/journal.pone.0016747

Swedish Population Substructure Revealed by Genome-Wide Single Nucleotide Polymorphism Data

Elina Salmela et al.

Abstract

The use of genome-wide single nucleotide polymorphism (SNP) data has recently proven useful in the study of human population structure. We have studied the internal genetic structure of the Swedish population using more than 350,000 SNPs from 1525 Swedes from all over the country genotyped on the Illumina HumanHap550 array. We have also compared them to 3212 worldwide reference samples, including Finns, northern Germans, British and Russians, based on the more than 29,000 SNPs that overlap between the Illumina and Affymetrix 250K Sty arrays. The Swedes - especially southern Swedes - were genetically close to the Germans and British, while their genetic distance to Finns was substantially longer. The overall structure within Sweden appeared clinal, and the substructure in the southern and middle parts was subtle. In contrast, the northern part of Sweden, Norrland, exhibited pronounced genetic differences both within the area and relative to the rest of the country. These distinctive genetic features of Norrland probably result mainly from isolation by distance and genetic drift caused by low population density. The internal structure within Sweden (FST = 0.0005 between provinces) was stronger than that in many Central European populations, although smaller than what has been observed for instance in Finland; importantly, it is of the magnitude that may hamper association studies with a moderate number of markers if cases and controls are not properly matched geographically. Overall, our results underline the potential of genome-wide data in analyzing substructure in populations that might otherwise appear relatively homogeneous, such as the Swedes.

Link

9 comments:

Jyril said...

Not surprising, considering the northernmost part of Sweden used to be Finnish-speaking. Many place names there are Finnish or corruptions from Finnish. There are still Finnish speaking people in the Torne River valley.

apostateimpressions123 said...

The Swedes - especially southern Swedes - were genetically close to the Germans and British, while their genetic distance to Finns was substantially longer.

That is very interesting! Swedes are much closer genetically to Germans (and to British!) than to Finns.

Does it reflect ancient Germanic origins or simply the extreme distinctiveness (and variation) of Finns?

Im guessing that Swedes would have a closer phenotype to Finns than to British?

Remarkably the mtDNA levels are almost identical between England and Germany for each of the 14 haplogroups listed here:

http://www.eupedia.com/europe/european_mtdna_haplogroups_frequency.shtml

eurologist said...

I have always maintained that there are signs for three ancestral populations in Sweden (plus a Finnish contribution). This paper, especially the local PC1+2 and wider, 3-D PC1+2+3 plots nicely demonstrate this. Southern Swedes are essentially almost identical with the most northern Germans (i.e., from the earliest northern agriculturalists, plus frequent mixing through the millennia). But then, in addition to the northernmost Sami contribution, there is always an additional, north-central Swedish cluster that shows up, which I would identify with an original, non-agriculturalists, non-Sami population.

This study also shows (via the relatively large genetic variation) that the data cannot simply be explained by drift and isolation.

The large Fst distance to Russians (larger than between Russians and Germans) also has a couple of interesting interpretations. Firstly, it confirms that the R1a in much of central Europe and Scandinavia is very old (at least going back to the beginning of agriculture, if not earlier) - as confirmed with ancient y-DNA studies. That is, R1a from the much more recent Slavic expansion encompasses distinct subclades (which did not penetrate into parts of Poland, the Baltic, and Serbia/Croatia). Secondly, the people that used the Eastern rivers to trade with the very south may not have been Scandinavians but Germans - or else, they did not have a significant genetic impact there, as once was thought.

Davidski said...

eurologist, what are you babbling about?

Slavic R1a1a1 is found all over Poland, from top to bottom and east to west, and deep into Germany.

It comes in several forms, including...

- M458 aka. R1a1a1g aka. Peter Gwozdz's N type (the old R1a1a7), most likely associated with proto-Slavs of Central-Eastern Europe.

- L260 aka. R1a1a1g2 aka. Peter Gwozdz's P type (the old R1a1a7b), the "Polish" haplogroup.

- L365 aka. R1a1a1i aka. Peter Gwozdz's G type, potentially associated with one or more of the ancient Southern Baltic shore cultures, like the Wielbark.

All three branches most likely originated in, or at least very close to modern Poland.

eurologist said...

Davidski,

Whether you believe in dates resulting from the Zhivitovsky rate or not, R1a1a is clearly very old, and based on diversity its origin is South Asia. It is ludicrous to call R1a1a1 "Slavic", when it also clearly predates any notion of "Slavic" linguistically or culturally.

Yet, we may be saying almost the same thing: R1a1a1 is widely distributed in Europe and very old, but the specific branches that can be associated with Slavic expansion and some (actually, a minority of) present-day Slavic speakers show a pattern that concentrates around the Ukraine and southern Poland - while the R1a1a branches in the Balkans, Germany, Scandinavia, the Baltics (and even western Poland) are different (save for recent immigrants, of course). Also note that even Gwozdz's P type only makes up ~8% of the Polish population! That is, there is a much older, clearly pre-Slavic substrate in Poland, as well.

In other words, the Slavic expansion is mostly linguistic and cultural, but petered out genetically (even in y-DNA) very quickly away from its origin in areas that were already (or at that point) heavily populated (thus accounting for the special cases of parts of Russia and the Czech republic).

This is similar to the Baltic population, which genetically clearly locally predates the arrival of the Baltic languages.

mikej2 said...

After seeing that Eastern Finns are so distant for the Vologda Russians it is more obvious what I have suggested; all Northern people, Norwegians, Swedes, Finns and Nothern Russians have got their Asian affinity separately by mixing with different semiarctic hunters after their northward expansions. Norwegians, Finns, Swedes and Russians all moved from the south. There is no other serious explanation.

The gap between eastern Finns and Russians also gives us genetic proofs of two waves of the populating of Finland. The first wave came from south and second from east before the last phase of Slavic expansion. Though this is a historic fact, it is good to see that also genetics support it. If things have gone by some other way, we shouldn't have this gap.

Surprisingly the Northern Russians seems to be at the same distant from Western Finns, Swedes and Germans. Obviously Slavs would hit much closer them, but but anyway it is interesting to see this in a historic perspect. I wonder how this can be explained taking into account language differences in Finland and those Germanic countries.

eurologist said...

I wonder how this can be explained taking into account language differences in Finland and those Germanic countries.

In autosomal studies, Hungary always comes out extremely close to Germany - yet it also belongs to that same large&lose Finno-Ugric language group (that extends from Europe and the Urals into much of Siberia). So, as I mentioned before, language can spread with very little genetic impact (IIRC there is some identifiable, small amount left in Hungarian y-DNA).

Strat said...

"In autosomal studies, Hungary always comes out extremely close to Germany - yet it also belongs to that same large&lose Finno-Ugric language group (that extends from Europe and the Urals into much of Siberia). So, as I mentioned before, language can spread with very little genetic impact (IIRC there is some identifiable, small amount left in Hungarian y-DNA)."

Unlike Finnish, the Hungarian language arrived and spread at a relatively recent time and in a densely populated area. For Hungarian, a much better analogy would be the arrival and spread of the Turkish language in a densely populated area, in what is now Turkey and its environs, at about the same time with that of Hungarian in what is now Hungary and its environs.

Fanty said...

Language scientists beleive that its possible that Germany becomes an englisch speaking country before the year 2100.

And that with almost zero migration.

They come up with this:
childrfen in the age group 14-21 had to explain a thing, using only 100 words.

In 1980 they used 2 (from the 100 words) english words.

1990 they used 4 english words.

2000 they used 10 english words.
2004 they used 25 english words (a quarter!)

I dont know any more recent numbers.

So they came up with the warning, that the existance of the German language is endangered, and the goverment should invoke a counter strategy to save the German language. Otherwise it would be a realistic guess, that there is no German speaker left by 2100.