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Proof or counter-proof... this is how to do it.

higgins at ebi.ac.uk higgins at ebi.ac.uk
Thu Jul 13 04:38:41 EST 1995

You still have not answered my post ludde:  why are you so against such a
potentially useful model;  what is it about the molecular clock hypothesis
that arouses such antagonism (especially in some groups of people)??


In article <3u1c1d$hbh at studium.student.umu.se>, Ludvig Mortberg <Agneta.Guillemot at historia.umu.se> writes:
> Thanks everyone for responding to my sceptical article on the  
> molecular clock. Your opinions are valuable. Thanks to them I  
> think I'm closer to defining methods of proving or disproving the  
> theory of the molecular clock, as I prefer to call it. 
> The following criteria should be satisfied if there is a clock. If not,  
> the clock is in trouble. 
> (1) Phylogenies, divergence dates etc, obtained by the clock,  
> should conform with fossil data. 

Within the errors (stastical and experimantal) inherent in both types of data.

> (2) When different parts of the genome are used in an analysis the  
> results should be the same. Different chromosomes, protein  
> sequences etc should give the same divergent dates or  
> phylogenies. Of course  it may not be possible to draw conclusions  
> from data from a very slowly evolving protein. Histones for  
> example. 

NO!!!!!  e.g. the Y chromosome (or parts of it) in mammals goes faster
than the X.  e.g. different proteins go at totally different rates if you
use amino acid distances or non-synonymous nucleotide distances.  

> (3) The Wilson relative rate test should be positive when applied  
> to three reasonably closely related species. See illustration below: 
>       / A 
>     /  
>   / 
> /\    / B 
>    \/ 
>      \ C 
> We have determined that B and C are closest. The distance from  
> B to A, be it nuclear substitutions or melting temperatures for  
> DNA-DNA hybrids, should of course be the same as the distance  
> from C to A. Otherwise B and C have evolved with different  
> speeds. 
> The last test may be the one that is most useful in determining  
> wether there is a clock or not. 
> Now what does the data say?  

Why don't you look first??

> Ludde 

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