Re: The driving force of evolution

In article <f9664d$1lce$1@xxxxxxxxxxxxxxxxxxx>, "John W Edser" <edser@xxxxxxxxxxxxxx> wrote:

first_name@xxxxxxxxxxxxx (Florian) wrote:-
"The new mutation theory of phenotypic evolution" by Masatoshi Nei
PNAS | July 24, 2007 | vol. 104 | no. 30 | 12235-12242
Abstract
Recent studies of developmental biology have shown that the genes
controlling phenotypic characters expressed in the early stage of
development are highly conserved and that recent evolutionary changes
have occurred primarily in the characters expressed in later stages of
development. Even the genes controlling the latter characters are
generally conserved, but there is a large component of neutral or nearly
neutral genetic variation within and between closely related species.
Phenotypic evolution occurs primarily by mutation of genes that interact
with one another in the developmental process. The enormous amount of
phenotypic diversity among different phyla or classes of organisms is a
product of accumulation of novel mutations and their conservation that
have facilitated adaptation to different environments. Novel mutations
may be incorporated into the genome by natural selection (elimination of
preexisting genotypes) or by random processes such as genetic and
genomic drift. However, once the mutations are incorporated into the
genome, they may generate developmental constraints that will affect the
future direction of phenotypic evolution. It appears that the driving
force of phenotypic evolution is mutation, and natural selection is of
secondary importance.
http://www.pnas.org/cgi/content/full/104/30/12235

JE:-
This is just back-to-the-future, stuff. The mutationists were wrong in the
past and they remain wrong, today. Chance selection (random mutation and
genetic drift) cannot compete and win against non random selection. The
problem which needs to be addressed here, i.e. not just evaded is, how can
genetics account for all the heritable differences between say, a chimp and
a human when over 99% of the genes that code for anything at all remain the
same in both.

Not even true. When it comes down to what matters most - proteins -
80% of them are not identical between chimps and humans.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pubmed&pubmedid=15716009

What's important to remember here is that there are plenty of examples
where a single mutation in a single protein alters the way an entire cell or
a whole organism behaves. Therefore, the 80% difference (even when
most of the difference may be restricted to a single amino acid) looks
very significant and can easily account for the difference between
species.

Note: both have only tiny genomes (20,000 or so coding genes).
The answer that makes the most sense to me is that NON additive genetic
epistasis accounts for _most_ of the _heritable_ variation along with above
the gene level forms of inheritance like gene imprinting. Both remain
deleted from popular Neo Darwinian models.

The answer that makes most sense is that when a single amino acid
can alter the functioning of the whole organism and when we don't have
capacity to faithfully model this series of events, we can't possibly
have any clue as to what changes are "important" and what are not.
In other words, forgetaboutit, any attempt to account for the difference
are as reliable as attempts of predicting consequences of cold summer
in Texas on corn harvest in Iowa.

DK




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