Quasispecies Theory and the Behavior of RNA Viruses
Figure 2
The fitness landscape and survival of the flattest.
(A) Population 1 has high fitness but is trapped in sequence space because mutation leads to a dramatic loss of fitness. Population 2 is more mutationally robust because mutation leads to minor fitness losses. The flatter population is ideally situated to move through sequence and access other local peaks through neighboring mutational networks (indicated in different colors). (B) At low mutation rates, variants will be genotypically stable and cluster at the top of the fitness peak. The variant with the highest fitness will easily outcompete all others. At high mutation rates, variants spread out over the corresponding peaks. Variants on the flatter peak (green) remain near their fitness optimum and have a higher mean fitness than the population located on the steeper peak (red). The flatter population will prevail.