Thursday, November 8, 2012

Molecular Dissection of the Basal Clades in the Human Y Chromosome Phylogenetic Tree

Rosaria Scozzari, Andrea Massaia, Eugenia D’Atanasio, Natalie M. Myres, Ugo A. Perego, Beniamino Trombetta, Fulvio Cruciani
PLOS ONE, November 2012
(Open Access link)

Published today is a new paper on an updated y-chromosome phylogeny.  Dienekes has kindly put the phylogeny and abstract online, so I won't recopy them here. 

The most significant finding of the paper is the connection of four A1b y-chromosomes, the deepest phylogeny in the tree, to two men from Ghana, one man in Cameroon and one in Algeria: "Two A1b chromosomes from a previous work (one from Algeria and one from Cameroon) [16] were included in this study together with two newly identified A1b chromosomes, whose geographic origin can be traced back to west-central Africa (Ghana) on the basis of the microsatellite profile (data not shown). It is worth noting that three additional A1b chromosomes have been recently found in Caribbean populations, which exhibit substantial Y-STR haplotype sharing with Y chromosomes from Gabon [35], [36]. Taken together, all these data reinforce the hypothesis of an origin in the north-western quadrant of the African continent for the A1b haplogroup [16], and, together with recent findings of ancient Y-lineages in central-western Africa [19], provide new evidence regarding the geographical origin of human MSY diversity."

A second finding is the identification of "a chromosome from southern Europe as a new deep branch within haplogroup C (C-V20 or C7, Figure S1). Previously, only a few examples of C chromosomes (only defined by the marker RPS4Y711) had been found in southern Europe [32], [33]. To improve our knowledge regarding the distribution of haplogroup C in Europe, we surveyed 1965 European subjects for the mutation RPS4Y711 and identified one additional haplogroup C chromosome from southern Europe, which has also been classified as C7 (data not shown). Further studies are needed to establish whether C7 chromosomes are the relics of an ancient European gene pool or the signal of a recent geographical spread from Asia." 

The paper also includes better definition of other aspects of the A and B y-chromosomes as well as some important additions to the basal F y-chromosome.

It's great to see more in depth attention paid to the genetics of West Africa and also nice to see Italy considered both as a refuge and as a potential path for Out of Africa expansions.

Related:

News Flash:  Developments with Y Haplogroup A (link)

For those of you new to this blog, in the right hand side bar under "WEST AFRICA", there is a list of the posts covering culture, language, geography and genetics of West Africa.

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