John Edser wrote:
>>WA:-
>>The most minimal definition of evolution is merely "a change in gene
>>frequencies," thus if a population can be shown to have had a change in
> 
> the
> 
>>content of its genome over some observable period of time, then evolution
>>can
>>be said to have occurred.
>>However it is very important to note that this definition explains
> 
> nothing,
> 
>>no
>>more than measuring a change in the angle of the sun during the course of
> 
> a
> 
>>day
>>explains the nature of celestial mechanics. Both are only easily
>>accomplished
>>empirical measures of readily observable physical qualities.
> 
> 
>>JE:-
>>The definition of evolution as  "a change in gene
>>frequencies" does not exclude random changes in
>>gene freq. Thus the definition is incorrect because
>>it allows a _non_ testable view of evolution.
> 
> 
> BOH:-
> Not so, see for example Mueller et al. (1985) Genetics 110: 495-511.
> The specifically test changes in allozyme frequency changes to see if
> the changes could be caused by genetic drift (sampling error is even
> easier to test for).
> 
> JE:-
> Incorrect. All random patterns, without
> exception, can be validly suggested
> to be caused by _either_ random or
> non random processes. This is because non random
> processes commonly produce random patterns
> but random processes can only produce random
> patterns, by definition. This being the case,
> it is logically _impossible_ to refute
> any claim of evolution being caused by just
> a random process. 

Rubbish.  Read something simple on stochastic processes.  Random 
processes can be characterised by their properties (means, variances 
etc.), and then thesecan be compared with the data.

To bring it to the biology - the amount of variation due to genetic 
drift depends on the effective population size (N_e).  Mueller et al. 
measured N_e in the butterfly, and then used that to see if the changes 
in allozyme allele frequencies were small enough to compatible with the 
variation expected from genetic drift.  In several cases the variation 
was much larger than expected.

Bob

-- 
Bob O'Hara

Rolf Nevanlinna Institute
P.O. Box 4 (Yliopistonkatu 5)
FIN-00014 University of Helsinki
Finland
Telephone: +358-9-191 23743
Mobile: +358 50 599 0540
Fax:  +358-9-191 22 779
WWW:  http://www.RNI.Helsinki.FI/~boh/
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