Behe vs. constructive neutral evolution
Posted in Biology on August 31st, 2011 by GutsI thought I'd add an informational post as a response to Behe's new post criticizing the CNE theory of complexity. He writes:
The last step of the model is the “co-adaptation” of the two proteins, where other, complementary mutations occur in both proteins. Yet this implies that the protein complex must suffer deleterious mutations at least every other step, provoking the “co-adaptive” mutation to fix in the population. Wouldn’t these deleterious mutations be very unlikely to spread in the population?
We're actually talking here about slightly deleterious or neutral mutations and only in small populations. Still, my problem with CNE is actually that it downplays evolvability aspects. Regardless , here's a recent Nature publication 'Non-adaptive origins of interactome complexity' by Fernández A. and Lynch M. and the reaction of W. Ford Doolittle to that article are relevant to the whole CNE discussion.
This leads to the hypothesis that the accumulation of mildly deleterious mutations in populations of small size induces secondary selection for protein–protein interactions that stabilize key gene functions. By this means, the complex protein architectures and interactions essential to the genesis of phenotypic diversity may initially emerge by non-adaptive mechanisms.
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