Evolution Requires Reduction in Genetic Diversity

Worth pointing out in this context is that there is now considerable evidence of selection on non-coding DNA. As an example, see Positive and Negative Selection on non-coding DNA in Drosophilia simulans, chosen because it was one of the first relevant papers I found that was available as a free pdf rather than for any particular significance. Some non-coding DNA appears to be of adaptive signifcance, at least in fruit flies and humans, where this has been investigated in most depth.Edited by caffeine, : No reason given.Edited by caffeine, : tags

But the problem is that it is not clear any such thing exists. I linked earlier to [/url=http://genomics.princeton.edu/...files/Haddrill_etal2008.pdf]a study[/url] that tested neutrality of non-coding DNA in two species of Drosophila. Their conclusion (emphasis mine):

quote:

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In summary, we have examined patterns of evolution at several classes of noncoding DNA in D. simulans and find that all noncoding DNA is subject to the action of negative selection, indicated by low levels of polymorphism and divergence and a skew in the frequency spectrum toward rare variants.

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I lack the expertise to assess the maths behind their claims, but if they're right then we can see detectable evidence of negative selection against changes in non-coding DNA. They also claim evidence of positive selection in untranslated DNA in Drosophila simuans.