Theoretical community ecology

Using exclusion rate to unify neutral and niche perspectives
Yohay Carmel, Yevhen F. Suprunenko, William E. Kunin, Rafi Kent, Jonathan Belmaker, Avi Bar-Massada, and Stephen J. Cornell

Understanding the processes that allow species to coexist is crucial for informing nature conservation. Classical ecological theory focuses on binary outcomes: two species either coexist indefinitely, or one ultimately excludes the other. However, ecological communities are always subject to disturbance, so a more pertinent question may be: how long will two species coexist? By focusing on exclusion rate rather than binary outcomes. We show that similarity in competitive strength often plays a stronger role in facilitating coexistence than differences in resource use, in contrast to prevailing ecological theory. Both very similar, and very dissimilar, species may coexist for long periods. This may help explain the coexistence in nature of diverse sets of species competing for a limited number of resources.

A 3D graph illustrating the relations between niche overlap, similarity in competitive ability, and exclusion rate