Before revision:  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 .
After revision:  This new theory unifies URLanism-specific mechanisms and tradeoffs into a single general 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 .