Co-Evolutionary Dynamics of Bacterial Communities

Microbes function as part of diverse communities that play key roles in determining the health of virtually all living organisms, as well as that of the entire planet. In order to manage and design communities, it is crucial to be able to predict their structure - that is, to predict which species will coexist stably, and which will be driven extinct. While there are recent advances in predicting the structure of bacterial communities over short time scales, little is known about the stability community structure over hundreds of generations, where evolution plays a significant role. The goals of this research are to study the stability of community structure over evolutionary time scales; to study the repeatability of changes in community structure across replicates, and to identify factors that influence those features.

For these purposes, we propagate 121 unique combinations of 16 bacterial species for ~400 generations and track their community structure, measure their interspecies interactions, and sequence their genomes. Our data reveal significant variation in stability across communities, with some communities changing significantly after as little as ~60 generations, while others remain stable for hundreds of generations. These changes were different when species evolved separately or together, suggesting that they are influenced by coevolution, rather than solely adapting to the experimental conditions. This study will reveal the time scales over which microbial community structure is predictable, and the factors that influence this predictability. This knowledge is crucial for engineering communities that function stably over hundreds of generations.