The Role of Chance in the Survival of the Fittest

The spreading of evolutionary novelties across populations is the central element of biological adaptation. Models of evolutionary spread have ignored, until quite recently, the randomness inherent in the reproduction process. But having excellent genes is not sufficient to be successful in evolution - one also needs luck to avoid accidents or to be at the right place at the right time. Using microbial evolution experiments and simulations, I elucidate the role of chance in evolutionary processes and show that deterministic models indeed fail to predict the dynamics of evolution as it is observed in microbial evolution experiments. I present novel approaches, combining modeling and experiments, that explain the observed patterns of genetic diversity, spatial spread and adaptation at a cellular scale, where self-driven jamming can impede the expansion, and at a global scale, where the dynamics is sped up by long-range dispersal.