Microbial invasions influence plant-microbiome feedback and coexistence

Plant-soil feedback (PSF) theory leverages the increasingly recognized ecological significance of microbiomes to provide insight into plant coexistence. However, PSF theory generally assumes that microbiomes have static composition and properties. In reality, plant communities are thought to commonly experience microbial colonization. Here, we use a PSF model to study microbial invasions of a community of two plant species and their associated microbiomes. We manipulate initial plant and microbiome evenness, microbial colonization timing, and properties of all actors, then record resulting community membership. Invasion success is higher during transient dynamics than when approaching equilibrium. Furthermore, stability analysis of a set of communities shows that invasion success is determined by the effects of the plants and the invader on each other’s growth rates. When successful, microbial invaders commonly disrupt plant coexistence. Our study demonstrates a promising framework for understanding biodiversity dynamics via integration of host-microbiome dynamics, dispersal, and time-dependent interactions.