The Relative Importance of the Competition Colonization Trade-off and the Storage Effect for Coexistence and Stabilit

Species coexistence may often involve multiple mechanisms. Hence, it is important to understand the relative importance of each mechanism. The storage effect and the competition colonization trade-off are well studied mechanisms for species coexistence but little is known of their interaction. We use a two-species spatial model, where one species is the superior colonizer and the other is the superior competitor, competition ranges from pure preemption to pure dominance, and colonization rates vary stochastically. Analytic results show that the storage effect promotes coexistence for all levels of preemption competition but the relative importance of the storage effect for the persistence of the superior competitor increases with the with the preemptive ability of the superior colonizer. Simulation results show the magnitude of the storage effect is maximal at intermediate reproductive numbers. We also show two measures of stability, resilience and temporal stability, have opposing responses to varying levels of preemption competition. This work highlights the importance of interactions between coexistence mechanisms when examining species coexistence and community stability.