April 21, 2005

Y-chromosome Lineages from Portugal, Madeira and Açores

A very interesting new paper on Portuguese Y-chromosomes. Three important conclusions are derived from the study of Sub-Saharan African, E3b, and J1 lineages in Portugal. The Sub-Saharan component seems to be small (0.7%) unlike the corresponding mtDNA component. The E3b lineages are highly heterogeneous, and include various sub-types, including the Aegean E-M78 cluster α as well as North African E3b2 and Middle Eastern E3b3. Interestingly, the North African component seems to be primarily of earlier Berber rather than historical Moorish origin:
North African component at least for mtDNA, is mainly concentrated in the North of Portugal. The mtDNA and Y data indicate that the Berber presence in that region dates prior to the Moorish expansion in 711 AD. Our Y chromosome results are also consistent with a continuous and regular assimilation of Berbers in North of Portugal. This argues against previous interpretations of Moorish mediated contributions, based on Y chromosome data (Bosch et al. 2001; Pereira et al. 2000b; Cruciani et al. 2004) and provides an alternative view of an earlier Berber presence in the North of Portugal.

Finally, the J lineages in Portugal are mainly in the J2 clade, but there is a substantial presence of the J1 clade as well, which is found in Arabs and Jews and not as often in European populations. The Portuguese J1 chromosomes cluster around the Cohen Modal Haplotype, rather than the known modal haplotypes of the Arabs. Therefore, it seems probable that these were introduced by Sephardic Jews, rather than Arabs.

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Annals of Human Genetics (OnlineEarly)

Y-chromosome Lineages from Portugal, Madeira and Açores Record Elements of Sephardim and Berber Ancestry

Rita Gonçalves et al.


A total of 553 Y-chromosomes were analyzed from mainland Portugal and the North Atlantic Archipelagos of Açores and Madeira, in order to characterize the genetic composition of their male gene pool. A large majority (78-83% of each population) of the male lineages could be classified as belonging to three basic Y chromosomal haplogroups, R1b, J, and E3b. While R1b, accounting for more than half of the lineages in any of the Portuguese sub-populations, is a characteristic marker of many different West European populations, haplogroups J and E3b consist of lineages that are typical of the circum-Mediterranean region or even East Africa. The highly diverse haplogroup E3b in Portuguese likely combines sub-clades of distinct origins. The present composition of the Y chromosomes in Portugal in this haplogroup likely reflects a pre-Arab component shared with North African populations or testifies, at least in part, to the influence of Sephardic Jews. In contrast to the marginally low sub-Saharan African Y chromosome component in Portuguese, such lineages have been detected at a moderately high frequency in our previous survey of mtDNA from the same samples, indicating the presence of sex-related gene flow, most likely mediated by the Atlantic slave trade.


1 comment:

Charles said...

I would rather say that the transaharan slave trade was critical in creating the clear sex bias in regards to the mitochondrial L found in Iberia. Females were favored two to one during this period to serve as wives, concubines and servants. This was mediated by both Moorish and Jewish groups which had extensive slave trade routes in Africa. On the other hand, the transatlantic slave trade favored men two to one to serve as serfs cutting sugar cane in the fields. Men would have been preferred at this time to survive the arduous transatlantic treck.

Here is a reference to the transaharan slave trade and the sex bias entailed in the phenomena: