Stochastic Phenotype Switching to Counteract Fluctuations in the Environment

Source: Acar et al. (2008). Stochastic switching as a survival strategy in fluctuating environments. Nature Genetics 40(4):471-475.

Previously, I had a post regarding phenotypic differences in populations with identical genotypes (Dr Jeckyll and Me Hyde). There, we made the case that persistence, as a switching phenotype, can help isogenic populations survive adverse changes in the environment. Here, the authors have modeled this problem in a more general format implying that the stochastically switchable phenotypes counteract the fluctuations in the environment.

The authors have engineered the GAL bistable switch in yeast to design two distinct strains: fast switchers and slow switchers. They have also envisioned two different environments (E1 and E2) each of which are suitable for one of these two switching paces (see figure below).

Using both mathematical and experimental models, the authors show that fast switching cells hold an advantage in rapidly changing environments while slow switchers do better in more stable conditions. In other words, the pace of stochastic switches can evolve in response to the fluctuations in the environment as an adaptive response for higher survival rate.