Global epistasis makes adaptation predictable despite sequence-level stochasticity

Abstract

Clouding evolution's crystal ball Because of a sort of mutation buffering process, different starting mutations can tend to end up with similar overall affects on an organism's fitness. Kryazhimskiy et al. evolved lines of yeast, each originating from distinct single genotypes, under the same selective regimen. A subset of clones from these adapted populations was subjected to fitness assays and sequenced. Populations with lower initial fitness, adapted more rapidly than populations with higher initial fitness, so that in the end the fitness levels were similar. Science , this issue p. 1519