When competing species expand into new territory, the population is dominated by descendants of a few successful ancestors at the expansion front. Successful ancestry is stochastic, but biased by fitness of the individual, as well as favorable geographic location. I will describe a simple model of range expansion of competing bacteria, in which reproduction and competition only take place at the growing front. Based on symmetry considerations a pair of nonlinear stochastic partial differential equations are constructed that describe the coevolution of the profile of the growing surface and the composition of the bacterial species on the front. Macroscopic manifestations (phenomenology) of these equations on growth morphologies (patterns) and genealogical tracks of range expansion will be presented.