Towards understanding factors influencing the benefit of diversity in predator communities for prey suppression

Abstract

It is generally assumed that high biodiversity is key to sustaining critical ecosystem services, including prey suppression by natural predator guilds. Prey suppression is driven by complex interactions between members of predator and prey communities, as well as their shared environment. Because of this, empirical studies have found both positive and negative effects of high predator diversity on prey suppression. However, we lack an understanding of when these different prey suppression outcomes will occur. In this work, we use a mechanistic, trait-based model to unravel how intraguild interactions, species body mass, predator foraging area, and ambient temperature can combine to produce different levels of prey suppression. Surprisingly, we find that prey suppression is only improved by high biodiversity under a limited set of conditions. The most important factor in determining whether diversity improves prey suppression is the amount of overlap between predators' foraging areas. The degree of overlap in foraging areas shapes species interactions, and as the overlap between species increases, we see decreasing benefits from species-rich communities. In contrast, diversity in body mass only improves prey suppression when there is significant variation in temperature.