Before revision:  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.
After revision:  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 resource use efficiency and preemption ability.