A study published in the Journal of Statistical Mechanics: Theory and Experiment (JSTAT), inspired by the behavior of bacterial colonies observed in previous experiments, uses mathematical models to describe the expansion of competing populations. The aim is to understand which factors determine the success of one population over another. According to the study, fitness — understood here as a reproductive advantage — is not the only factor involved, nor is it necessarily the decisive one: expansion speed and position along the growth front also matter. The shapes of the expanding front predicted by the model closely resemble those observed in earlier experiments of microbial colonies. The study also makes a new prediction: that spatial structure leaves a measurable fingerprint on how fitness is distributed across a population, which new experiments could look for.
