Intelligent Design

Gene Expression and Evolvability

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The twentieth century unveiled the world of molecular biology, including DNA, the genetic code, proteins, and the molecular basis for modern genetics. Such findings, according to Neo Darwinists, nicely supported evolution. Evolutionary change was fueled by variation arising from genetic mutations. How the genes, and their supporting cast, arose in the first place was a more difficult question. But given their existence the evolutionary narrative was held with great confidence. This straightforward narrative is now understood, however, to be too simplistic. For instance, we now understand that biological variation often arises not from changes in the genes but rather from changes in the expression levels of the genes. Even those celebrated beaks of Darwin’s finches appear to be changing via variation in gene expression levels. And more significant variation, such as body plan differences in related insects, also correlate with varying gene expression levels. These new findings do not bode well for traditional evolutionary theory.  Read more

6 Replies to “Gene Expression and Evolvability

  1. 1
    Nakashima says:

    Dr Hunter,

    But the mechanisms that influence the gene expression levels are not simple. They involve proteins and DNA sequences.

    Proteins – those things coded for by DNA? and more DNA? So DNA (genes) isn’t completely responsible, more DNA and stuff made from DNA instructions is also responsible. That helps explain why DNA matters so little in explaining evolution. Thanks!

    With the traditional theory of evolution we must believe that mutations created such mechanisms, one step at a time while they had little or no ability to influence expression levels.

    Sounds like a prediction of duplicate genes. What’s that you say, Bunky? Your genome has more Hox boxes than Dr Seuss has fox sockses?

    Not only are the mechanisms complex, but they must arise in the right place.

    Or they could arise in the “wrong” place and selection could weed them out. Just sayin’.

    The mechanism, if it works correctly, becomes invaluable. But until then it waits.

    Which, in a population of variants, isn’t a difficult scenario.

    In other words, evolution created the mechanisms which caused more evolution to occur—evolution creates evolution.

    Or put the brakes on too much duplication, more likely.

  2. 2
    bornagain77 says:

    Refuting Nak:

    Assessing the NCSE’s Citation Bluffs on the Evolution of New Genetic Information – Feb. 2010
    http://www.evolutionnews.org/2.....ion_b.html

    How to Play the Gene Evolution Game – Casey Luskin – Feb. 2010
    http://www.evolutionnews.org/2.....ution.html

    Simulating evolution by gene duplication of protein features that require multiple amino acid residues: Michael J. Behe and David W. Snoke
    Excerpt: 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.,,,The fact that very large population sizes—10^9 or greater—are required to build even a minimal [multi-residue] feature requiring two nucleotide alterations within 10^8 generations by the processes described in our model, and that enormous population sizes are required for more complex features or shorter times, seems to indicate that the mechanism of gene duplication and point mutation alone would be ineffective, at least for multicellular diploid species, because few multicellular species reach the required population sizes.
    http://www.pubmedcentral.nih.g.....id=2286568

    Experimental Evolution of Gene Duplicates in a Bacterial Plasmid Model
    Excerpt: In a striking contradiction to our model, no such conditions were found. The fitness cost of carrying both plasmids increased dramatically as antibiotic levels were raised, and either the wild-type plasmid was lost or the cells did not grow. This study highlights the importance of the cost of duplicate genes and the quantitative nature of the tradeoff in the evolution of gene duplication through functional divergence. http://www.springerlink.com/co.....4014664w8/

    The Origin of Biological Information and the Higher Taxonomic Categories – Stephen Meyer”Neo-Darwinism seeks to explain the origin of new information, form, and structure as a result of selection acting on randomly arising variation at a very low level within the biological hierarchy, mainly, within the genetic text. Yet the major morphological innovations depend on a specificity of arrangement at a much higher level of the organizational hierarchy, a level that DNA alone does not determine. Yet if DNA is not wholly responsible for body plan morphogenesis, then DNA sequences can mutate indefinitely, without regard to realistic probabilistic limits, and still not produce a new body plan. Thus, the mechanism of natural selection acting on random mutations in DNA cannot in principle generate novel body plans, including those that first arose in the Cambrian explosion.”

    Stephen Meyer – Functional Proteins And Information For Body Plans – video
    http://www.metacafe.com/watch/4050681

    Cortical Inheritance: The Crushing Critique Against Genetic Reductionism – Arthur Jones – video
    http://www.metacafe.com/watch/4187488

  3. 3
    scordova says:

    But the problems do not stop there. For such mechanisms, even when fully operational, would have limited usefulness. They must await environmental challenges to reveal their true worth. When such challenges arise the expression levels of those certain genes must change in the right way. The mechanism, if it works correctly, becomes invaluable. But until then it waits.

    Such mechanisms are contingency mechanism. Natural Selection will have a hard time selecting for such features for reasons which were outline here:
    Airplane magnetos contingency designs and reasons ID will prevail.

    Selection can select for features that don’t yet exist. It can select for contingency designs it doesn’t readily see, and in fact it can select against contingencies if they are metabollically expensive to carry.

  4. 4
    Nakashima says:

    scordova,

    Natural Selection will have a hard time selecting for such features…

    Nope. Say a gene duplication happens due to random variation, and the change begins to drift randomly through the population. Over time, population members suffer failures of copies of the gene through other kinds of variation. Members with one copy die, members with two copies live (selection). The population is going to be taken over by members with either or both copies working.

    Heritable variation and selection. Its a beautiful thing.

  5. 5
    Mung says:

    Natural Selection will have a hard time [b]selecting for[/b] such features.

    Nope.

    “Selection for” is teleological. It’s not something a non-teleological process can do.

    Heritable variation and selection. Its a beautiful thing.

    Teleology. It’s a beautiful thing.

    Natural selection is either teleological, or it isn’t.

    My claim is that it is.

  6. 6
    Nakashima says:

    Mr Mung,

    Natural selection is either teleological, or it isn’t.

    My claim is that it is.

    Is your claim supported by evidence that you can share, or is your claim an assertion that you would like us to join you in believing.

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