Eco-evolutionary causes and genomic consequences of synergistic coevolution

• Applicants: Dr. Alexander Herbig; Professor Dr. Christian Kost
• Subject Area: Microbial Ecology and Applied Microbiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 525853121

A major challenge in evolutionary biology is to understand how interactions between different organisms shape the process of coevolution. While this issue is well-understood for antagonistic interactions (e.g. between parasites and their hosts), our knowledge on synergistic coevolution is rather poorly developed. Specifically, it remains unclear how ecological interactions determine the evolutionary dynamics of coevolving populations and thus the mutational trajectories of the individuals involved. This includes in particular the question whether and how synergistic coevolution affects the rates of molecular evolution and phenotypic diversification within interacting consortia. Answering these questions requires not only knowledge on the order and identity of mutations that occurred during coevolution, but also detailed mechanistic insights into the ecological consequences these mutations have for the focal interaction partners. This project will address these issues by taking advantage of a previously performed coevolution experiment, in which a cooperative mutualism evolved between two genotypes of the bacterium Escherichia coli. Both isolated strains and whole populations will be longitudinally sequenced to unravel the order and distribution of mutations that arose during synergistic coevolution. In addition, isolated and genetically reconstructed strains will be subjected to carefully designed coculture experiments to clarify how individual mutations affect the evolutionary dynamics of interacting genotypes on both a cell- and a population-level. In this way, the experimental tractability of the focal model system will help to identify the underlying eco-evolutionary mechanisms and thus helpt to understand other types of mutualistic interactions, in which similar analyses are frequently not possible. The results of this study are expected to significantly advance the development of an empirical framework of synergistic coevolution that will be highly relevant in both applied and fundamental research contexts.

• DFG Programme: Research Grants