Genetic Chaos

Friday, November 03, 2006

Geographical, Linguistic, and Cultural Influences on Genetic Diversity: Y-Chromosomal Distribution in Northern European Populations

We analyzed 10 Y-chromosomal binary markers in 363 males from 8 populations in Northern Europe and 5 Y microsatellites in 346 of these individuals. These populations can be grouped according to cultural, linguistic, or geographical criteria, and the groupings are different in each case. We can therefore ask which criterion best corresponds to the distribution of genetic variation. In an AMOVA analysis using the binary markers, 13% of the Y variation was found between populations, indicating a high level of differentiation within this small area. No significant difference was seen between the traditionally nomadic Saami and the neighboring, historically farming, populations. When the populations were divided into Uralic speakers and Indo-European speakers, 8% of the variation was found between groups, but when they were divided according to geographical location, 14% of the variation was between groups. Geographical factors have thus been the most important in limiting gene flow between these populations, but linguistic differences have also been important in the east.

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Y-chromosome diversity in Sweden – A long-time perspective

Sixteen Y-chromosomal binary markers and nine Y-chromosome short tandem repeats were analyzed in a total of 383 unrelated males from seven different Swedish regions, one Finnish region and a Swedish Saami population in order to address questions about the origin and genetic structure of the present day population in Sweden. Haplogroup I1a* was found to be the most common haplogroup in Sweden and accounted, together with haplogroups R1b3, R1a1 and N3, for over 80% of the male lineages. Within Sweden, a minor stratification was found in which the northern region Va¨sterbotten differed significantly (Po0.05) from the other Swedish regions. A flow of N3 chromosomes into Vasterbotten mainly from Saami and Finnish populations could be one explanation for this stratification. However, the demographic history of Vasterbotten involving a significant male absence during the 17th Century may also have had a large impact. Immigration of young men from elsewhere to Varmland at the same time, can be responsible for a similar deviation with I1a* haplotypes. Y chromosomes within haplogroup R1b3 were found to have the highest STR variation among all haplogroups and could thus be considered to be one of the earliest major male lineages present in Sweden. Regional haplotype variation, within R1b3, also showed a difference between two regions in the south of Sweden. This can also be traced from historical time and is visible in archaeological material. Overall this Y chromosome study provides interesting information about the genetic patterns and demographic events in the Swedish population.

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