Predator-Mediated Coexistence of Competing Species in a Volterra Model

We examine the possibility of predator-mediated coexistence of all species with model ecosystems of Volterra type. We are concerned with dynamics of a biological community of three competing species to which one predator is added. Stability at equilibria increases when a predator is included. Oscillatory coexistence in limit cycles or in chaotic motions is also possible with a predator. Stable coexistence is enhanced if a predator prefers a dominant competitor. Even when coexistence of species in the subcommunities is impossible, four species can coexist.