How Does Drift Contribute to Adaptive Evolution?

[Rumraket (Mikkel R.)]

There was a thread around here not long ago that showed how this kind of genetic drift also contributes to the evolution of new protein functions:

Cryptic genetic variation accelerates evolution by opening access to diverse adaptive peaks

New paper from Andreas Wagner & colleagues that touches on topics of perennial interest (and debate) here. Here is the abstract in case the paper is paywalled: Abstract Cryptic genetic variation can facilitate adaptation in evolving populations. To elucidate the underlying genetic mechanisms, we used directed evolution in Escherichia coli to accumulate variation in populations of yellow fluorescent proteins and then evolved these proteins toward the new phenotype of green fluorescence. Populations with cryptic variation evolved adaptive genotypes with greater diversity and higher fitness than populations without cryptic variation, which converged on similar genotypes. Populations with cryptic variation accumulated neutral or deleterious mutations that break the constraints on the order in which adaptive mutations arise. In doing so, cryptic variation opens paths to adaptive genotypes, creates historical contingency, and reduces the predictability of evolution by allowing differe…