Potential Contribution of Microbial Interaction to Stochasticity of Microbiota Assembly

Abstract Microbial interaction has been widely acknowledged as the deterministic factor for microbiota assembly. However, such interaction is highly variable in practice and may lead to the random birth, death and reproduction of neighboring microbes, potentially contributing to stochastic assembly processes. Here, we developed a Go-board model to simulate and investigate how microbiota assembly was affected by different types of interacting species, interaction strength, and community structure. The infer Community Assembly Mechanisms by Phylogenetic-bin-based null model analysis (iCAMP) shows that the strong inhibition of deterministic species on stochastic ones can switch the dominant assembly process from heterogeneous selection to drift. On the other hand, inhibition of stochastic species on their deterministic neighbors enhances the relative importance of dispersal limitation in the community with small deterministic population. The mutual inhibition between deterministic and stochastic species further enhances the stochasticity of microbiota assembly, but this effect is canceled out by the interspecific facilitation and deterministic species with large phylogenetic distance. Our study sheds novel light on the role of microbial interaction in stochastic assembly processes, which is contradictory to the traditional niche-based theory. It highlights the importance of assessing interspecific interaction for predicting the true roles of different assembly processes in future studies.