Predator Switching Strength Controls Stability in Diamond-Shaped Food Web Models

In food web models that include more than one prey type for a single predator, it is common for the predator's functional response to include some form of switching-preferential consumption of more abundant prey types. Predator switching promotes coexistence among competing prey types and increases diversity in the prey community. Here, we show how the dynamics of a diamond-shaped food web model of a marine plankton community are sensitive to a parameter that sets the strength of predator switching. Stronger switching destabilizes the model's coexistence equilibrium and leads to the appearance of limit cycles. Stronger switching also increases the evenness of the asymptotic prey community and promotes synchrony in the dynamics of disparate prey types. Given the dependence of model behavior on the strength of predator switching, it is important that modelers carefully consider the parameterization of functional responses that include switching.