The interplay between ecological networks drives host-plasmid community dynamics

Plasmids can accelerate host adaptation through horizontal gene transfer and are key members of microbial communities. Plasmid infection dynamics are potentially affected by the interplay between the structures of host-plasmid and plasmid-plasmid interactions. However, how the structures of these networks jointly affect plasmid transmission and community dynamics remains unstudied. We used an agent-based model to simulate the dynamics of a multihost-multiplasmid system in which we manipulated the structure of the ecological networks. The interplay between network structures affects host coexistence, population composition, and plasmid prevalence. For instance, plasmid incompatibility and a modular host-plasmid network promoted host coexistence. These effects were largely driven by the structure-induced dynamics of the co-infected individuals in microbial populations. A combination of modeling and a lab experiment further showed that the structure of the host-plasmid network determines plasmid fate. This study demonstrates how interactions between multiple ecological networks affect the dynamics and fate of infectious agents and their hosts. The structure of the ecological networks within microbial communities therefore has implications for the evolutionary potential of these communities.