2009年10月31日

Evolution has no reverse

Whether evolution can go back to an ancestral structure just by reversing the selection pressure on function has been a long-standing issue but one hard to address based on just the history of forms.

Bridgham et al. have nowphysically reconstituted ancient versions of a regulatory protein (the glucocoricoid receptor) and dissected the structural constraints imposed on the evolution of their function (which hormone they bind) at atmic resolution.

They find that amino acids that were essential in an ancestral protein become newtral in a more recent from, where they are then subject to erosion by genetic drift.

This loss deprives natural selection of the necessary raw material with which to reverse the historical substitutions ― they are no longer 'adaptive' as they were in the other direction.

Evolutionarily spealing, there is no turning back.


### DataBace ###
nature Vol.461 837-1018 Issue no.7266 15 Octiber 2009
Letter p.515
Abstractions p.446
posted by 0≠素子 at 18:21| Comment(0) | evolution | このブログの読者になる | 更新情報をチェックする
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