A new conceptual framework for host-microbe symbiosis

Host-microbe relationships are studied across biological disciplines, with different but related discipline-specific conceptual frameworks arising from each of them. Without a unified framework that can be applied across all symbioses, we cannot do the interdisciplinary work necessary to understand the underlying rules that govern symbiosis. Here I present a new conceptual framework for host-microbe symbiosis, rooted in its original definition, across three axes of fitness effects, partner fidelity and transmission mode. The three axes make a cube where any symbiotic relationship can be placed. The position of a particular symbiosis is fluid and context-dependent, changing through evolution and throughout the lifetime of an organism. The three axes make for a simple and inclusive framework for symbiosis. We can use this framework to examine every known symbiosis, we will be able to understand the rules and patterns that govern them.