How reliable is mitochondrial DNA as a marker for tracking population flow?

Question

Quote, "We conclude that natural selection acting on mtDNA contributes to homogenization of the average diversity among groups, in agreement with the genetic draft theory. mtDNA appears to be anything but a neutral marker and probably undergoes frequent adaptive evolution, e.g., direct selection on the respiratory machinery, nucleo-cytoplasmic coadaptation, two-level selection, or adaptive introgression, perhaps hitchhiking with a maternally transmitted parasite. mtDNA diversity is essentially unpredictable and will, in many instances, reflect the time since the last event of selective sweep, rather than population history and demography."

There's also evidence that Mt DNA can sometines be inherited from the father. They've also found seriously ancient X chromosomes in Mbuti Pygmies and East Asians that support hybridization with archaic poulations.

Is the hybrid origin theory gaining ground?

Answer 1

I, as an evolutionary biologist, am immediately drawn to the phrase, " two level selection. " Not well known, but known by some, that the multi-regionalism position is quite dependent on selection other than individual/gene selection. In fact, their position is welded to group selection, for which only a very limited amount of evidence and in special circumstances is available. Secondly, you forget the other convergent line of evidence, Y chromosome evidence.

Thirdly, you do not give a name to your quote and this is not an " argument from authority ", but of the evidence.

mtDNA is subject to a high rate of random mutation and none has claimed anything like " neutral marker " status for mtDNA. So, I suspect a bit of a " straw man " argument is being made here.

I find it suspicious that you do not " tag " your quote, so that it can be researched in context.

So, why is finding seriously ancient X's among African tribes evidence for hybrid origins?

Answer 2

MtDNA is useful for determining the Haplogroup of the mother & linage, just is the Y Chromosome is useful for determining the father & his male ancestors.  However, it can't determine 2nd generation hybrids in ~50% of the cases.  Given several generations, either chromosome becomes useless in determining hybridization or "gene introgression."  These are 2 of our very smallest chromosomes (forgot the # of genes contained by them.)

Without sequencing the entire genome, we throw out the baby with the bath water, as Chromosome 8 & 13 contain some of the most interesting genes.

I do think gene introgression is gaining ground, but we have to be very careful about the evidence that's released.  Any mistake will be amplified to discredit the "regional hypothesis."  The OOA crowd does the best they can to portray supporters of the regional view as kooks likely to see UFOs & such.  It does appear the debate has pushed back the migration date a bit (Out of Africa).  Therefore the debate is forcing further research by both sides of the arguement. See below.

http://www.sciencedaily.com/releases/200...