Re: Behe, Snoke Article

Jack,
Not being a statistician or into proteomics, I can only give a guess, but
it seems to me that this is based on pure chance. My impression is that
genetic change has additional factors that "direct" evolution. I think I
recall some work on bacteria some time back that indicated that the
required changes in a stressful situation occurred more often than chance
would dictate. Hope somebody who knows these areas responds to you.
Dave

On Thu, 14 Jul 2005 08:57:15 -0400 Jack Haas <haas.john@comcast.net>
writes:
>
> Greetings:
>
> Would any of you like to comment on this article?
>
> Jack Haas
> ______
>
> Published online before print August 31, 2004, 10.1110/ps.04802904
> Protein Science (2004), 13:2651-2664
> Copyright © 2004 The Protein Society
>
> Simulating evolution by gene duplication of protein features that
> require multiple amino acid residues
> Michael J. Behe1 and David W. Snoke2
>
> 1 Department of Biological Sciences, Lehigh University, Bethlehem,
> Pennsylvania 18015, USA
> 2 Department of Physics and Astronomy, University of Pittsburgh,
> Pittsburgh, Pennsylvania 15260, USA
>
> (RECEIVED April 8, 2004; FINAL REVISION June 17, 2004; ACCEPTED June
> 17, 2004)
>
> Gene duplication is thought to be a major source of evolutionary
> innovation because it allows one copy of a gene to mutate and
> explore genetic space while the other copy continues to fulfill the
> original function. Models of the process often implicitly assume
> that a single mutation to the duplicated gene can confer a new
> selectable property. Yet some protein features, such as disulfide
> bonds or ligand binding sites, require the participation of two or
> more amino acid residues, which could require several mutations.
> Here we model the evolution of such protein features by what we
> consider to be the conceptually simplest route—point mutation in
> duplicated genes. We show that for very large population sizes N,
> where at steady state in the absence of selection the population
> would be expected to contain one or more duplicated alleles coding
> for the feature, the time to fixation in the population hovers near
> the inverse of the point mutation rate, and varies sluggishly with
> the {l!
> ambda}th root of 1/N, where {lambda} is the number of nucleotide
> positions that must be mutated to produce the feature. At smaller
> population sizes, the time to fixation varies linearly with 1/N and
> exceeds the inverse of the point mutation rate. We conclude that, in
> general, to be fixed in 10^8 generations, the production of novel
> protein features that require the participation of two or more amino
> acid residues simply by multiple point mutations in duplicated genes
> would entail population sizes of no less than 10^9.
>
> Keywords: gene duplication; point mutation; multiresidue feature;
> disulfide bonds; ligand binding sites
>
> Abbreviations: MR, multiresidue
>
> Article published online ahead of print. Article and publication
> date are at
> http://www.proteinscience.org/cgi/doi/10.1110/ps.04802904.
>
> Reprint requests to: Michael J. Behe, Department of Biological
> Sciences, Lehigh University, 111 Research Drive, Bethlehem, PA
> 18015, USA; e-mail: mjb1@lehigh.edu; fax: (610) 758-4004.
>
> ________
>
>
>
Received on Thu Jul 14 17:11:22 2005