🚀 go-pugleaf

In article <29517@castle.ed.ac.uk>, rambaut@castle.ed.ac.uk (A E Ram aut) writes:
|> swf@tools3teradata.com (Stan Friesen) writes:
|> 
|> >No, this will not work.  For a change to count as evolutionary, it *must*
|> >be inheritable, that is it must be genetic.  This is because non-heritable
|> >changes are not propagated, and thus cannot be *accumulated* - which makes
|> >the whole process rather meaningless.
|> 
|> Phenotype is by definition inheritable because the phenotype is the
|> physical manifestation of the genotype an inheritable set of alleles.

Well, that is not how I use the terms.  I use phenotype to mean "the physical
manifestation of the organism", no reference to genes.

The problem is that a given gentoype can produce many different specific
phenotypes, depending on the environment.  Thus it is entirely possible for
the physical manifestation to change without any change in genotype.

A good example of this is the increase in height in North America and Europe over
the last several centuries.  There is no evidence that there has been *any*
genetic change with regard to height, and, yet height can be shown to have
a very high heritability (about as high a heritability as has ever been observed).

What is happening?  The answer is better nutrition.  This is *not* evolution,
it is just environmental effects.  As soon as nutrition returns to medieval
levels the mean height will drop back to the old value in the next generation.

It is this sort of change that must be seperated from evolutionary change,
and which is not by a definition based on phenotype.

-- 
sarima@teradata.com			(formerly tdatirv!sarima)
  or
Stanley.Friesen@ElSegundoCA.ncr.com