Coexistence of poorer competitors for all available resources requires greater niche overlap

Abstract The need for niche differentiation among resource competitors to coexist is a universally accepted principle in ecology. However, this principle is derived from models with one or two resources or no resource dynamics at all. Graphical analysis of a consumer‐resource model including three resources shows that a consumer that is not the best competitor for any single resource can coexist with two consumers that are the best competitors for one and two resources, respectively, if it has high diet/niche overlap and so strongly competes with one or both other competitors for two of the resources. The same community structure emerges in randomly assembled communities with up to six consumers feeding on six resources: Up to half of the consumers can be the best competitor on no available resource. Specifically, consumers that are the best competitor for at least one available resource have low diet overlap with one another, and consumers that are the best competitor for no resource have high diet overlap with the best competitors on at least one resource and among themselves. Coexistence of these consumers requires higher niche overlap with competitors that are the best competitors for multiple resources and permits even higher niche overlap among themselves.