Irreducible Complexity

Michael Behe on the most recent Richard Lenski “evolvability” paper

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In my own view, the most interesting aspect of the recent Lenski paper is its highlighting of the pitfalls that Darwinian evolution must dance around, even as it is making an organism somewhat more fit. (1) If the “wrong” advantageous mutation in topoisomerase had become fixed in the population (by perhaps being slightly more advantageous or more common), then the “better” selective pathway would have been shut off completely. And since this phenomenon occurred in the first instance where anyone had looked for it, it is likely to be commonplace. That should not be surprising to anyone who thinks about the topic dispassionately. As the authors note, “Similar cases are expected in any population of asexual organisms that evolve on a rugged fitness landscape with substantial epistasis, as long as the population is large enough that multiple beneficial mutations accumulate in contending lineages before any one mutation can sweep to fixation.” If the population is not large enough, or other factors interfere, then the population will be stuck on a small peak of the rugged landscape.

This fits well with recent work by Lenski’s and others’ laboratories, showing that most beneficial mutations actually break or degrade genes (4), and also with work by Thornton’s group showing that random mutation and natural selection likely could not transform a steroid hormone receptor back into its homologous ancestor, even though both have very similar structures and functions, because the tortuous evolutionary pathway would be nearly impossible to traverse. (5, 6) The more that is learned about Darwin’s mechanism at the molecular level, the more ineffectual it is seen to be.

One Reply to “Michael Behe on the most recent Richard Lenski “evolvability” paper

  1. 1
    bornagain77 says:

    This evidence from Lenski’s work also fits these studies;

    Michael Behe Hasn’t Been Refuted on the Flagellum!
    Excerpt: Douglas Axe of the Biologic Institute showed in one recent paper in the journal Bio-complexity that the model of gene duplication and recruitment only works if very few changes are required to acquire novel selectable utility or neo-functionalization. If a duplicated gene is neutral (in terms of its cost to the organism), then the maximum number of mutations that a novel innovation in a bacterial population can require is up to six. If the duplicated gene has a slightly negative fitness cost, the maximum number drops to two or fewer (not inclusive of the duplication itself).
    http://www.evolutionnews.org/2.....44801.html

    Testing Evolution in the Lab With Biologic Institute’s Ann Gauger – podcast with link to peer-reviewed paper
    Excerpt: Dr. Gauger experimentally tested two-step adaptive paths that should have been within easy reach for bacterial populations. Listen in and learn what Dr. Gauger was surprised to find as she discusses the implications of these experiments for Darwinian evolution. Dr. Gauger’s paper, “Reductive Evolution Can Prevent Populations from Taking Simple Adaptive Paths to High Fitness,”.
    http://intelligentdesign.podom.....4_13-07_00

    Response from Ralph Seelke to David Hillis Regarding Testimony on Bacterial Evolution Before Texas State Board of Education, January 21, 2009
    Excerpt: He has done excellent work showing the capabilities of evolution when it can take one step at a time. I have used a different approach to show the difficulties that evolution encounters when it must take two steps at a time. So while similar, our work has important differences, and Dr. Bull’s research has not contradicted or refuted my own.
    http://www.discovery.org/a/9951

    The Evolutionary Accessibility of New Enzyme Functions: A Case Study from the Biotin Pathway Ann K. Gauger and Douglas D. Axe*
    Excerpt: After identifying and testing 29 amino-acid changes, we found three groups of active-site positions and one single position where Kbl2 side chains are incompatible with BioF2 function. Converting these side chains in Kbl2 makes the residues in the active-site cavity identical to those of BioF2, but nonetheless fails to produce detectable BioF2-like function in vivo. We infer from the mutants examined that successful functional conversion would in this case require seven or more nucleotide substitutions. But evolutionary innovations requiring that many changes would be extraordinarily rare, becoming probable only on timescales much longer than the age of life on earth.
    http://bio-complexity.org/ojs/.....O-C.2011.1

    —————–

    ,,, I could probably understand why a neo-Darwinist would suspect the experimental work of Doug Axe, and company, but what I really want to know is why neo-Darwinists refuse to accept the results of their very own experiments? It certainly takes a extreme amount of ‘denialism’ to ignore the fact that Lenski’s evolved strain are much less ‘fit’ than when they started with!

    The Long Term Evolution Experiment – Analysis
    Excerpt: The experiment just goes to show that even with historical contingency and extreme selection pressure, the probability of random mutations causing even a tiny evolutionary improvement in digestion is, in the words of the researchers who did the experiment, “extremely low.” Therefore, it can’t be the explanation for the origin and variety of all the forms of life on Earth.
    http://www.scienceagainstevolution.org/v12i11f.htm

    Michael Behe’s Quarterly Review of Biology Paper Critiques Richard Lenski’s E. Coli Evolution Experiments – December 2010
    Excerpt: After reviewing the results of Lenski’s research, Behe concludes that the observed adaptive mutations all entail either loss or modification–but not gain–of Functional Coding ElemenTs (FCTs)
    http://www.evolutionnews.org/2.....41221.html

    Lenski’s e-coli – Analysis of Genetic Entropy
    Excerpt: Mutants of E. coli obtained after 20,000 generations at 37°C were less “fit” than the wild-type strain when cultivated at either 20°C or 42°C. Other E. coli mutants obtained after 20,000 generations in medium where glucose was their sole catabolite tended to lose the ability to catabolize other carbohydrates. Such a reduction can be beneficially selected only as long as the organism remains in that constant environment. Ultimately, the genetic effect of these mutations is a loss of a function useful for one type of environment as a trade-off for adaptation to a different environment.
    http://www.answersingenesis.or.....n-bacteria

    New Work by Richard Lenski:
    Excerpt: Interestingly, in this paper they report that the E. coli strain became a “mutator.” That means it lost at least some of its ability to repair its DNA, so mutations are accumulating now at a rate about seventy times faster than normal.
    http://www.evolutionnews.org/2.....enski.html

    Is Antibiotic Resistance evidence for evolution? – ‘The Fitness Test’ – video
    http://www.metacafe.com/watch/3995248

    Thank Goodness the NCSE Is Wrong: Fitness Costs Are Important to Evolutionary Microbiology
    Excerpt: it (an antibiotic resistant bacterium) reproduces slower than it did before it was changed. This effect is widely recognized, and is called the fitness cost of antibiotic resistance. It is the existence of these costs and other examples of the limits of evolution that call into question the neo-Darwinian story.

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