Counter-proof against the molecular clock hypothesis

higgins at ebi.ac.uk higgins at ebi.ac.uk
Wed Jul 12 06:51:24 EST 1995


In article <3tuqp5$87a at sifon.cc.mcgill.ca>, Graham Dellaire <popa0206 at PO-Box.McGill.CA> writes:
> Hello all,
> 
> Well actually there is evidence that when you pick say myoglobin or some other
> gene and use accumulated mutations to determine divergence of two species there is 
> a serious flaw. The premise that mutations occur in these two genes, in two different 
> organisms in two different genomic contexts, at the same rate is most likely wrong.
> 
> It is well established and being accepted finally that the genome is made of
> many "domains" of which the accessibility to enzymes and oxidative agents etc
> that might cause damage to the DNA and  hence mutations differs.  The accessibility
> although not conclusively linked in all cases can reflect  transcription status, time of 
> replication and/or  rates of recombinaition.  It is already known that transcription and
> DNA repair (specifically Nucleotide Excision Repair) are intimately linked.  Now if you 
> have domains with different transcriptional activity you can have different rates of 
> mutation that is reflected in efficiency of DNA repair.
> 
> 
> So to make a long story short molecular clocks with such a basis are invariably inaccurate!
> 
> Graham



Strange then that myoglobin changes in such a clock-like manner when you
actually LOOK AT THE DATA.   Something is wrong somewhere, methinks.



Des









> 
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