EEB Tuesday Seminar Series - Keystone Predator and Keystone Intransitivity: The Potential Chaos of Competitive Coexistence

This event is part of our ongoing Tuesday Seminar Series.

About this seminar: The structure of ecological communities remains enigmatic, partly due to its dimensionality (many species interacting) and partly due to its network diversity (many ways to “wire” the interactions). It is also a subject of some practical importance, especially with current concern over the global biodiversity crisis. Venerable concepts, such as the competitive exclusion principle or the keystone predator hypothesis, are understood to frequently be embedded within that structure, and partially responsible for generating it. Here we approach the subject of community structure through a strategic intersection of several particular network modalities – competitive hierarchy, keystone predator, keystone intransitivity, and higher-order trait-mediated effects. Because predation and intransitive competition are both fundamentally oscillatory, the theoretical framework of coupled oscillators comes into play, a mathematical structure well-known to be a major source of chaos. We use a set of natural history observations and measurements of a five dimensional system common in the coffee agroecosystem of Puerto Rico to show how the persistence of a subdominant competitor in a competitive hierarchy may be contingent on this particular wiring of the system.