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

Many ecological models treat exploitative competition in isolation from interference competition. Corresponding theory centers around the R* rule, according to which consumers that share a single limiting resource cannot coexist. Here we model motile consumers that directly interfere while handling resources, mechanistically capturing both exploitative and interference competition. Our analytical coexistence conditions show that interference competition readily promotes coexistence. In contrast to previous theory, coexistence does not require intraspecific interference propensities to exceed interspecific interference propensities or for interference behaviors to carry a direct (rather than merely an opportunity) cost. The underlying mechanism of coexistence can resemble the hawk-dove game, the dominance-discovery trade-off (akin to the competition-colonization trade-off), or a novel trade-off we call the “dove-discovery trade-off,” depending on parameter values. Competitive exclusion via the R* rule occurs only when differences in exploitative abilities swamp other differences between species, and it occurs more easily when differences in R* reflect different search speeds than when they reflect different handling times. Our model provides a mathematically tractable framework that integrates exploitative and interference competition and synthesizes previous disparate models.