Gut motility as a driver of microbial community architecture and host-microbe evolution

Digestive systems are dynamic, contractile ecosystems that continually shape the physical and chemical niches inhabited by gut microbes. Patterns of mixing and propulsion generate flow, shear, and nutrient gradients that select for microbial traits such as adhesion, biofilm formation, and metabolic timing. Microbial metabolites, in turn, influence smooth muscle excitability and enteric neural circuits, creating bidirectional feedback that structures microbial communities and affects host physiology. We argue that gastrointestinal motility, an ancient and nearly universal feature of metazoan digestive systems, functions as an evolutionary scaffold, linking microbial spatial organization with host neuromuscular diversification. Comparative evidence from cnidarians to mammals highlights how these interactions have shaped both microbial ecology and host adaptation, with relevance for understanding modern dysmotility-microbiome disorders.