Emergent evolutionary dynamics in dense cellular populations

Evolutionary dynamics are controlled by a number of driving forces, such as natural selection, random genetic drift and dispersal. While these forces are usually modeled at the population level, it is often unclear how they emerge from the stochastic and deterministic behavior of individual cells. I discuss how even the most basic mechanical interactions between neighboring cells can couple evolutionary outcomes of otherwise unrelated individuals, thereby weakening natural selection and enhancing random genetic drift. Using microbial examples of varying degrees of complexity, I highlight a feedback loop between ecological and evolutionary dynamics, which is particularly pronounced in pattern-forming systems. Understanding this feedback loop could be key to predicting and potentially steering evolutionary processes, and requires extending the systems biology approach from the cellular to the population scale.