A Mechanistically Integrated Model of Exploitative and Interference Competition over a Single Resource Produces Widespread Coexistence

Abstract

Most ecological theory emphasizes exploitative competition and ignores interference competition. Much corresponding theory centers around theR*rule, which predicts that consumers who share a single limiting resource cannot coexist, because the superior exploitative competitor excludes the inferior. Here we model motile consumers that directly interfere during the resource handling stage, mechanistically capturing the dynamics of both exploitative and interference competition. We derive analytical coexistence conditions, which show that interference competition readily promotes coexistence. In contrast to previous theory, coexistence does not require intra-specific inference propensities to exceed inter-specific interference, nor for interference behaviors to carry a direct (rather than merely an opportunity) cost.R*theory holds only within a narrow parameter value regime, given interference competition. The parameters that affect exploitative competitive ability also strongly modulate interference competition, and the latter rather than the former are sometimes responsible for competitive exclusion. When coexistence does occur, the underlying mechanisms often resemble either the competition-colonization trade-off or the Hawk-Dove game, canonical models from community ecology and evolutionary game theory, respectively. Our model therefore provides a tractable and more generalized framework to understand resource competition that synthesizes previous disparate models into a single framework.