Cryptic genetic variation promotes rapid evolutionary adaptation in an
RNA enzyme
Nature 474, 7349 (2011). doi:10.1038/nature10083
Authors: Eric J. Hayden, Evandro Ferrada & Andreas Wagner
Cryptic variation is caused by the robustness of phenotypes to mutations. Cryptic variation has no effect on phenotypes in a given genetic
or environmental background, but it can have effects after mutations or environmental
change. Because evolutionary adaptation by natural
selection requires phenotypic variation, phenotypically revealed cryptic genetic
variation may facilitate evolutionary adaptation. This
is possible if the cryptic variation happens to be pre-adapted, or “exapted”, to a new environment, and is thus advantageous once revealed.
However, this facilitating role for cryptic variation has not been proven,
partly because most pertinent work focuses on complex phenotypes of whole
organisms whose genetic basis is incompletely understood. Here we show that
populations of RNA enzymes with accumulated cryptic variation adapt more rapidly
to a new substrate than a population without cryptic variation. A detailed
analysis of our evolving RNA populations in genotype space shows that cryptic
variation allows a population to explore new genotypes that become adaptive
only in a new environment. Our observations show that cryptic variation contains
new genotypes pre-adapted to a changed environment. Our results highlight
the positive role that robustness and epistasis can have in adaptive evolution.
No comments:
Post a Comment