Scally, A., Durbin, R., 2012. Nat Rev Genet 13, 745-753. PERSPECTIVE.
Rather than using a phylogenetic
approach to estimate the mutation rate to calibrate the ‘molecular clock’ (i.e.
using a fossil of a known date to anchor the divergence time between two species)
these authors advocate using de novo mutation rates between parent and
offspring trios. This halves the
suggested mutation rate to 0.5x10-9 bp-1 year-1,
although this depends on generation time.
Using this rate they re-calculate (i) the Neanderthal-AMH divergence to
~500kya, which is inline with mtDNA estimates, (ii) the split between Khoe-San
and other modern humans to 250-300kya (which is older than the single locus
estimates for the root of the human tree and requires re-evalaution of the
models of dispersion across the globe), (iii) the split between the Yoruba and
non-Africans to 90-130kya (meaning the Skhul-Qafzeh population might not be an
earlier ‘failed dispersion’ population after all and potentially giving Middle
Eastern Neanderthals and AMH a longer period of interbreeding) and (iv)
European-Asia split re-dated to 40-80kya.
The revised mutation rate doubles the effective population size
parameter, which again may affect previous models of AMH dispersals out of
Africa.
No comments:
Post a Comment