An eco-evolutionary consumer-resource theory of host-microbe symbioses

Symbiotic associations between microorganisms and hosts are universal, diverse, and dynamic. Yet, our ability to represent this complexity mathematically remains limited. We propose extending consumer-resource theory to incorporate evolutionary processes to advance our understanding of symbioses, from pairwise interactions to complex host-microbe assemblages. The resulting eco-evolutionary framework captures feedbacks between host-microbe interaction structure, biotic resource availability, and selection acting across biological scales. Importantly, this approach relaxes the assumption of separated ecological and evolutionary timescales, so that both processes unfold simultaneously. The coupling between ecological and evolutionary dynamics allows key properties of symbioses, such as ecological dependence and functional integration, to emerge from evolving resource-mediated interactions, rather than being imposed a priori. We illustrate the framework with a mathematical model of mycorrhizal symbiosis. The proposed consumer-resource formulation provides a unified basis for linking ecological and evolutionary dynamics in host-microbe symbioses, with implications for both basic theory and applied management.