Family tree Y-chromosomal Adam

the revised root of y-chromosome family tree cruciani et al. 2011 compared family tree karafet et al. 2008. has been further expanded discoveries published mendez et al. in 2013.

initial sequencing (karafet et al., 2008) of human y chromosome suggested 2 basal y-chromosome lineages haplogroup , haplogroup bt. haplogroup found @ low frequencies in parts of africa, common among hunter-gatherer groups. haplogroup bt lineages represent majority of african y-chromosome lineages , virtually non-african lineages. y-chromosomal adam represented root of these 2 lineages. haplogroup , haplogroup bt represented lineages of 2 male descendants of y-chromosomal adam.

cruciani et al. 2011, determined deepest split in y-chromosome tree found between 2 reported subclades of haplogroup a, rather between haplogroup , haplogroup bt. subclades a1b , a1a-t believed descend directly root of tree , represent lineages of y-chromosomal adam s 2 sons. rearrangement of y-chromosome family tree implies lineages classified haplogroup not form monophyletic clade. haplogroup therefore refers collection of lineages not possess markers define haplogroup bt, though haplogroup includes distantly related y chromosomes.

the m91 , p97 mutations distinguish haplogroup haplogroup bt. within haplogroup chromosomes, m91 marker consists of stretch of 8 t nucleobase units. in haplogroup bt , chimpanzee chromosomes, marker consists of 9 t nucleobase units. pattern suggested 9t stretch of haplogroup bt ancestral version , haplogroup formed deletion of 1 nucleobase. haplogroups a1b , a1a considered subclades of haplogroup both possessed m91 8ts.

but according cruciani et al. 2011, region surrounding m91 marker mutational hotspot prone recurrent mutations. therefore possible 8t stretch of haplogroup may ancestral state of m91 , 9t of haplogroup bt may derived state arose insertion of 1t. explain why subclades a1b , a1a-t, deepest branches of haplogroup a, both possess same version of m91 8ts. furthermore, cruciani et al. 2011 determined p97 marker, used identify haplogroup a, possessed ancestral state in haplogroup derived state in haplogroup bt.