Using traits to assess nontransitivity of interactions among coral species

Simulations and experiments have shown that species coexistence can be maintained via nontransitive competition, of which a simple case is the rock-paper-scissors game. Reef-building corals exemplify high biodiversity competing for a few limiting resources via several mechanisms. Thus, corals represent fertile ground for exploring competition and nontransitivity. This article aimed to test hypotheses about the effects of species-level traits on competitive outcomes, specifically, that more upright growth, larger corallites, smaller ranges, and difference in commonness co-occur with competitive superiority. Further aims were to test whether closely related species show less predictable competitive outcomes and greater nontransitivity and to examine the level of nontransitivity among a large number of species. These goals were addressed by fitting a mixed-effects model to outcomes of 2,322 interspecific interactions. Among species-level traits, corallite width had the greatest impact on o...