Tim Tyler  wrote in
news:cd6evr$jr6$1{at}darwin.ediacara.org: 

> William Morse  wrote or quoted:
> 
>> We have had lots of good clean fun on this newsgroup debating the 
>> relative contributions of drift and natural selection to evolution.
>> But as more and more sequence data becomes available, it is becoming
>> clear that both drifters and niche-pickers have missed the boat.
>> Gene, chromosome, and perhaps (if the above article is correct) even
>> genome duplication looms as a big kahuna in evolution, with drift and
>> selection only working their magic once duplication has created the
>> raw material. 
> 
> Shannon-wise, duplication adds very little information to a signal.
> 
> So - if you are using Shannon information as a metric to measure
> genetic change - duplicating the entire genome is a change of about
> the same magnitude as a typical point mutation.

The original duplication doesn't add much information - but what it does is 
allow drift and selection to create information that they otherwise could 
not. In other than small populations, drift is constrained by selection, 
and selection will not in general allow much change in working genes. But 
duplication gets around this difficulty - the original or perhaps the 
duplicate gene is still there to perform the required function, while drift 
gets to work on the other copy until the copy gets a chance to be 
expressed, when selection can take over. The duplicate has the additional 
advantage that its product is already well accepted by the rest of the 
genome, so a minor modification will probably also fit in. 


Yours,

Bill Morse
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