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. Here, we introduce to this theory the concept of preemption exploitation and demonstrate that multispecies coexistence is possible when there is a tradeoff between resource use efficiency and preemption ability. Moreover, our model predicts a transition from efficiency dominated communities to preemption dominated communities with increasing resource availability . This new theory unifies URLanism-specific mechanisms and tradeoffs into a single general tradeoff between preemption and efficiency that provides a mean of coexistence under resource competition .
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. Here, we extend resource competition theory to include hierarchical preemption exploitation and show that the conditions for coexistence are qualitatively different from that of equal exploitation. Under preemption exploitation, a necessary and sufficient condition for coexistence is that the R of the inferior species be lower than the superior preemptors. In other words, there should be a tradeoff between the ability to preempt the resource and R. Within the coexistence region, the relative abundance of the preemptor species increases as the difference in Rs decreases and as resource availability increases. Our results highlight the tradeoff between preemption ability and R as a coexistence mechanism that unifies seemingly distinct tradeoffs, i.e., various biological attributes lead to a negative relationship between being a gleaner (having low R) and preemption ability .
R
(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.
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.
R
introduce to this theory the concept of preemption exploitation and demonstrate that multispecies coexistence is possible when there is
extend resource competition theory to include hierarchical preemption exploitation and show that the conditions for coexistence are qualitatively different from that of equal exploitation. Under preemption exploitation, a necessary and sufficient condition for coexistence is that the R of the inferior species be lower than the superior preemptors. In other words, there should be
R
resource use efficiency and preemption ability. Moreover, our model predicts a transition from efficiency dominated communities to preemption dominated communities with increasing resource availability . This new theory unifies URLanism-specific mechanisms and tradeoffs into a single general
the ability to preempt the resource and R. Within the coexistence region, the relative abundance of the preemptor species increases as the difference in Rs decreases and as resource availability increases. Our results highlight the
R
and efficiency that provides a mean of coexistence under resource competition
ability and R as a coexistence mechanism that unifies seemingly distinct tradeoffs, i.e., various biological attributes lead to a negative relationship between being a gleaner (having low R) and preemption ability