Several questions on evolution, and mutation (rate)

Radford Neal radford at cs.toronto.edu
Tue Sep 10 12:14:02 EST 1996


In article <dyanega-0909961914040001 at catalpa.inhs.uiuc.edu>,
Doug Yanega <dyanega at denr1.igis.uiuc.edu> wrote:

>> >No. Evolution is a property of a population - "functions" do not evolve,
>> >they arise. Evolution is the underlying change in the genetic material,
>> >not the function that *results* from that change.

>> [R.Neal:] Looking at just one recent issue of Nature (11 July
>> 1996), I see the following uses of this terminology...

>That's because these folks are using the more colloquial sense of the
>term... each of the three cases you cite above are, in a rather literal 
>sense, shorthand for saying "evolutionary history"... but "evolution" - 
>the *process* - has a more specific definition... no evolution in ANY
>sense, whether it be the evolution of stamens, the evolution of proteins,
>or the evolution of trichromacy, *can* occur without a change in allele
>frequencies in some population somewhere. It is still the most
>all-inclusive concept. I might go so far as to say the _sine qua non_.

I would say that this is not the "more colloquial" sense of the term,
but rather its fundamental sense.  "Evolution" is a phenomenon,
observed in the fossil record, and inferred from the observed
similarities and differences between organisms today.  "Change in
allele frequencies" is an *explanation* for this phenomenon.

You have attempted to redefine "evolution" to refer to this explanation, 
rather than the phenomenon being explained.  This is sometimes a
useful maneouver, but only if you are really, really sure of your
explanation, and formulate your definition carefully.  "Change in
frequency of alleles" doesn't qualify in this respect.  To give yet
another example, do you really think that a re-organization of
chromosomes that leaves the set of alleles present unchanged is of no
evolutionary significance?  Your definition just doesn't work.  
 
    Radford Neal



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