Population genetics of non-genetic traits: Evolutionary roles of stochasticity in gene expression

•We proposed potential roles of the Stochasticity of Gene Expression in evolution.•We modeled fitness consequence of SGE.•We analyzed effects of SGE on effective population size and fixation probability.•SGE can alter the fate of mutations.•A genetic control of SGE magnitude can evolve under certain conditions.

The role of stochasticity in evolutionary genetics has long been debated. To date, however, the potential roles of non-genetic traits in evolutionary processes have been largely neglected. In molecular biology, growing evidence suggests that stochasticity in gene expression (SGE) is common and that SGE has major impacts on phenotypes and fitness. Here, we provide a general overview of the potential effects of SGE on population genetic parameters, arguing that SGE can indeed have a profound effect on evolutionary processes. Our analyses suggest that SGE potentially alters the fate of mutations by influencing effective population size and fixation probability. In addition, a genetic control of SGE magnitude could evolve under certain conditions, if the fitness of the less-fit individual increases due to SGE and environmental fluctuation. Although empirical evidence for our arguments is yet to come, methodological developments for precisely measuring SGE in living organisms will further advance our understanding of SGE-driven evolution.