Fig. 7 |. Phylogenetic reconstruction of human centromeric haplotypes and the saltatory amplification of new α-satellite HORs.

a, The strategy to determine the phylogeny and divergence times of completely sequenced centromeres using monomeric α-satellite or unique sequence flanking the canonical α-satellite HOR array from both the p- and q-arms. Chimpanzee was used as an outgroup with an estimated species divergence time of 6 million years ago (Ma). b, Maximum-likelihood phylogenetic trees depicting the p- and q-arm topologies along with the estimated divergence times reveal a monophyletic origin for the emergence of new α-satellite HORs within the chromosome 12 (D12Z3) α-satellite HOR array. This array shows a complex pattern of new α-satellite HOR insertions and deletions over a short period of evolutionary time. The asterisks indicate nodes with 100% bootstrap support, and nodes with 90–99% bootstrap support are indicated numerically. Nodes without an asterisk or number have bootstrap support <90%. The haplotypes from the p- and the q-arm trees are linked with a light teal bar, as shown in the schematic in a. Note that most differences in the order of the haplotypes occur at the terminal branches, where the order of sequence taxa can be readily reshuffled to establish near-complete concordance. Thus, there are no significant changes in the overall topologies of the phylogenetic tree. ka, thousand years ago.