The feasibility principle in community ecology

Serguei Saavedra

The structure and function of ecological communities emerge from interactions among populations within specific environmental contexts. Yet we still lack general principles that explain how communities assemble, which patterns we should expect, and when transitions occur across diverse settings. To address this challenge, I propose the feasibility principle in community ecology as a guide to assembly. Grounded in a synthesis of theoretical work and empirical studies, the principle is articulated through three hypotheses: (i) for a given interaction structure at a given time, each potential community has a feasibility domain---the range of environmental conditions under which it can persist; (ii) during assembly, the communities most likely to be observed are those whose feasibility domains overlap most with local conditions; and (iii) transitions among communities occur when environmental change or species gains and losses move the system across boundaries separating their feasibility domains, with the probability of a transition decreasing as the overlap between the corresponding domains becomes smaller. This framing focuses on feasibility domains and the boundaries that separate attainable communities, providing testable predictions for assembly and transitions without invoking a particular dynamical endpoint. I outline a quantitative framework to estimate feasibility domains and compare predictions with data across organisms and contexts. In the face of rapid climate change and habitat modification, I discuss how the feasibility principle can inform conservation and restoration by anticipating assembly pathways, likely transitions, and points of intervention.