Mitochondrial DNA

Discussion of everything related to the Theory of Evolution.

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iphysics
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Mitochondrial DNA

Post by iphysics » Thu Sep 04, 2008 1:12 pm

After reading Bryan Sykes' book, "The Seven Daughters of Eve", I came across a chapter which disucssed Mitochondrial DNA and how it is used to link back ancestory of organisms. I do understand this concept where the mitochondrial DNA is inherited from the mother and therefore is constant unless it undergoes mutions over the generations, but what I would like to understand is how Mitochondrial DNA can be used to determine relationships between organisms..

Thanks for the help!

Darby
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Post by Darby » Thu Sep 04, 2008 3:30 pm

The basic idea is that, on average, groups that "split" from a shared ancestor accumulate new mutations randomly along their separate tracks - if you compare species and the mitochondrial DNA is very similar, they are closely related...

It also is assumed that mutations accumulate, on average, at a set rate - the number of unshared mutations is used to determine how far back in time that shared ancestor lived.

In human populations, native Americans seem to derive from east Asians, based on the similarities in their mtDNA. In Africa, groups in the same basic area can be very different genetically, meaning humans have been there a long time and there hasn't been much crossing between those groups.

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