A chance at survival: gene expression noise and phenotypic diversification strategies

Phenotypic diversification plays a central role in evolution and provides species with a capacity to survive environmental adversity. The profound impact of random molecular events on the shaping of life is well accepted in the context of chance mutations and genetic drift; however, the evolution of the regulatory networks encoding microorganismal stress response and survival strategies might also have been significantly influenced by gene expression noise. This likelihood has inspired numerous investigations to characterize the sources of phenotypic diversity within isogenic populations, and to explore their direct and potential biological implications. Here, we discuss different scenarios where gene expression noise might bestow a selective advantage under stress, highlighting a potentially fundamental role of stochastic mechanisms in the evolution of microbial survival strategies.