Combined use of biallelic and microsatellite Y-chromosome polymorphisms toinfer affinities among African populations

To define Y-chromosome haplotypes, we studied seven biallelic polymorphic s ites. We combined data with those from four dinucleotide-repeat polymorphis ms, to establish Y-chromosome compound superhaplotypes. Eight biallelic hap lotypes that matched the dendrogram proposed by other investigators were id entified in 762 Y chromosomes from 25 African populations. For each biallel ic site, coalescence time of lineages carrying the derived allele was estim ated and compared with previous estimates. The "ancestral" haplotype (haplo type 1A) was observed among Ethiopians, "Khoisan" (!Kung and Khwe), and pop ulations from northern Cameroon. Microsatellite distributions within this h aplotype showed that the Khoisan haplotypes 1A are widely divergent from th ose of the other two groups. Populations from northern Africa and northern Cameroon share a haplotype (i.e., 1C), which is not observed in other Afric an populations but represents a major Eurasian cluster. Haplotypes 1C of no rthern Cameroon are clearly distinct from those of Europe, whereas haplotyp es 1C of northern African are well intermingled with those of the other two groups. Apportionment of diversity for the Y-chromosomal biallelic haploty pes was calculated after populations were clustered into different configur ations. Despite some correspondence between language affiliation and geneti c similarity, geographic proximity seems to be a better predictor of geneti c affinity.