Before revision: Resource competition theory (R* theory) predicts that the species with the highest efficiency (lowest resource requirements) will exclude all other species when competing over a single resource. This prediction contrasts the vast diversity in natural systems where there are often few limiting resources . We conjecture that this prediction is derived from the unrealistic assumption that all species acquire the same amount of the resource, i. e. equal exploitation.
After revision: Resource competition theory predicts coexistence and exclusion patterns based on species Rs, the resource levels of zero net growth. A major assumption of this theory is that all species have identical access to resources. However, many systems are characterized by preemption exploitation (e.g. asymmetric competition, contest competition) where some species deplete resources before encountering their competitors. Although preemption exploitation was incorporated into several system-specific and resource-specific models, these models lack the simplicity, generality, and analytical tractability of the classical theory.