Advantages and disadvantages of interference-competitive ability and resource-use efficiency when invading established communities

Invaders into established communities must overcome low resource availability. To establish, invaders must either appropriate resources from existing individuals through interference competition or efficiently use the small amount of resource that remains. Although both strategies may be important, they are rarely considered together and, in particular, resource-use efficiency is often ignored in systems dominated by interference competition. To identify the traits that confer invasion success, we experimentally invaded resource patches in established communities with multiple species from two functional groups that differ in interference competitive ability and resource-use efficiency. In contrast to previous assessments, we show that resource-use efficiency can facilitate invasion in systems dominated by interference competition. Furthermore, large resource requirements can be a liability when establishing because interference competition is inherently costly and so cannot fully compensate for limitations in the primary resource. However, we also show that there is a tradeoff in performance among functional groups between small and large resource gaps. Our results suggest we modify the way we view and manage species invasion in systems dominated by interference competition.