Re: Nei's "new mutation theory" resurrects William Bateson


"Arlin" <arlin.stoltzfus@xxxxxxxxx> wrote in message
news:fk7om2$h9o$1@xxxxxxxxxxxxxxxxxxxxxx


Thanks for asking. The opposing positions of the MS and Mutationism
are documented in "Mutationism and the Dual Causation of Evolutionary
Change" (Stoltzfus, 2006, Evol and Dev 8:304-17), and in the extensive
supplementary material, both of which you can request
(stoltzfu@xxxxxxxxxxxxxxxxxx, remove nospam). The documentation comes
in the form of direct quotations from the mutationists and the
architects of the MS. Reading the paper by Stoltzfus (2006) is a hard
slog but I promise that if you devote an hour or two to reading it you
will come away with a new understanding of evolutionary causation and
a more accurate perspective on how historical disputes relate to
present-day challenges in evolutionary biology.

Thanks for sending me your article. The last bit about bias was interesting,
but I didn't come away with a new understanding of evolutionary causation.
As far as I can see, MS-ists and mutationists all accepted and still accept
the same basic equations from population genetics. I do not find that
concepts like "intiative", "creativity", "directionality" add any insight to
these equations.

Here's a quick-and-dirty calculation. Population = N diploids,
mutation rate (per site per individual per generation) = u, selection
coefficient of a particular mutation = s (which I'm assuming is small-ish
and positive). Then you expect to wait about 1/(2Nus) generations for a
given mutation to arise and become established, and about (2/s)log(2N)
generations for it to sweep through the population. I'm quoting from memory,
and have probably dropped a factor of two somewhere, but at the level I want
to discuss here, that doesn't matter much. In fact, let's make a further
approximation. Since log(2N) only varies from about 7 to 21 as N varies from
a thousand to a billion, let's say it is 15, so we have 1/(2Nus) to wait for
a mutation to arise and become established, and 30/s for it to sweep
through. So you could say that the rate of mutation is the main limit on the
the rate of evolution when Nu < 1/60 or so. It makes as much sense to me to
blame N as u. So you could also say that the population size limits the rate
of evolution when Nu < 1/60. Perhaps someone should start advocating
"populationism".

See
http://nyuanshin.livejournal.com/109773.html
for an application of this sort of calculation to the recently reported
acceleration in human evolution.

See "The cost of natural selection revisited." Leonard Nunney.
www.sekj.org/PDF/anz40-free/anz40-185.pdf
for a computer simulation which is more realistic than my quick-and-dirty
calculation.


Graham


.

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