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Darwin’s beneficial mutations do not benefit each other.

Here.

Epistasis between Beneficial Mutations and the Phenotype-to-Fitness Map for a ssDNA VirusDarin R. Rokyta1*, Paul Joyce2, S. Brian Caudle1, Craig Miller3, Craig J. Beisel2, Holly A. Wichman3

Epistatic interactions between genes and individual mutations are major determinants of the evolutionary properties of genetic systems and have therefore been well documented, but few quantitative data exist on epistatic interactions between beneficial mutations, presumably because such mutations are so much rarer than deleterious ones . We explored epistasis for beneficial mutations by constructing genotypes with pairs of mutations that had been previously identified as beneficial to the ssDNA bacteriophage ID11 and by measuring the effects of these mutations alone and in combination. We constructed 18 of the 36 possible double mutants for the nine available beneficial mutations. We found that epistatic interactions between beneficial mutations were all antagonistic—the effects of the double mutations were less than the sums of the effects of their component single mutations. We found a number of cases of decompensatory interactions, an extreme form of antagonistic epistasis in which the second mutation is actually deleterious in the presence of the first. In the vast majority of cases, recombination uniting two beneficial mutations into the same genome would not be favored by selection, as the recombinant could not outcompete its constituent single mutations. In an attempt to understand these results, we developed a simple model in which the phenotypic effects of mutations are completely additive and epistatic interactions arise as a result of the form of the phenotype-to-fitness mapping. We found that a model with an intermediate phenotypic optimum and additive phenotypic effects provided a good explanation for our data and the observed patterns of epistatic interactions.

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2 Responses to Darwin’s beneficial mutations do not benefit each other.

  1. An Excellent study! Of course our neo-Darwinian friends will most likely deny this study means anything negative for their beloved theory.

    As well, from a poly-functiontional equals poly-constraint perspective (Sanford; Genetic Entropy)) this result is exactly what we should expect:

    Poly-Functional Complexity equals Poly-Constrained Complexity
    http://docs.google.com/Doc?doc.....Zmd2emZncQ

    ====================

    The Bacteriophage Virus – Assembly Of A Molecular “Lunar Landing” Machine – video
    http://www.metacafe.com/watch/4023122

    The first thought I had when I saw the bacteriophage virus is that it looks similar to the lunar lander of the Apollo program. The comparison is not without merit considering some of the relative distances to be traveled and the virus must somehow possess, as of yet unelucidated, orientation, guidance, docking, unloading, loading, etc… mechanisms. And please remember this level of complexity exists in a world that is far too small to be seen with the naked eye.

    The Bacteriophage Virus – A Molecular Lunar Landing Machine – video
    http://www.metacafe.com/watch/4205494

  2. If Darwinism were a living organism, the accumulation of deleterious mutations would have killed it off by now.

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