Speaker
Description
Community level evolution is an important, but understudied aspect of evolution. Directed evolution of communities can not only increase our understanding of evolution, but also has many potential applications, such as creating communities with specific functions. However, artificial evolution of communities has had limited success. Here we are interested in the co-evolution of communities in fluctuating environments. In particular, we ask if it is possible for organisms to evolve in a way that benefits the communities, but not themselves. To answer this question, we use a community composed of yeast and lactic acid bacteria. In the first environment, the yeast can grow well, but the bacteria need the yeast for growth. In the second environment, the bacteria grow well and the yeast cannot grow. We hypothesize that repeatedly cycling communities through these two environments and selecting for communities with highest biomass in the first environment should select for mutations that allow more yeast to persist in the second environment. Over the course of 40 cycles, we find that the biomass in the first environment fluctuates more in communities undergoing selection, compared to control communities with no selection imposed. In the second environment, the biomass of communities under selection decreases over the 40 cycles, where as in the control communities there is no monotonous decrease. Plating of the communities has revealed the presence of at least one bacterial mutant with a different colony morphology. The mutants and the final communities will be sequenced to understand these dynamics.
