A novel framework to modelling regulation of prey populations by a generalist predator

Abstract Background In ecological communities, a predator often feeds on several food sources. Such a predator is known as a generalist, and its feeding is traditionally modelled by a functional response. However, the conventional concept of the functional response is not applicable to predators for which feeding niches of individual predators are much narrower than that of the entire predator population. Therefore, the predator population effectively consists of cohorts of specialists, each of which has its specific diet. In this case, modelling predator-prey interactions requires an alternative approach. The objectives of this study are twofold. First, we provide an empirical example of a generalist predator consisting of cohorts of specialists to motivate our theoretical study. Second, we develop a mathematical framework to modelling food consumption of a generalist predator consisting of specialised feeders. Results Firstly, we experimentally show that the freshwater predatory snail Anentome helena , feeding on non-predatory snails, has individual feeding niches that are much narrower than that of the entire predator population. Then, we present a new generic framework to model food webs with a generalist predator consisting of individuals with very narrow feeding niches. The proposed modelling approach allows for switching among specialist cohorts, governed by variation in profitability of each foraging strategy. Using a model of trophic interactions, we show that structuring within the predator population promotes coexistence of competing prey species; however, the outcome depends on the initial configuration of specialist cohorts within the predator population. The system exhibits oscillations of prey densities while maintaining an approximately constant predator density; this pattern was not reported in previous predator-prey models. Conclusions We critically revisit the long-standing concept of the functional response of a generalist predator. We argue that if individual foragers within the predator population develop a stable preference for a particular food resource, feeding cannot be described using the traditional functional response modelling approach based on the total predator density. Using our new modelling framework, accounting for individual preferences, we demonstrate the existence of novel patterns of predator-prey dynamics. These patterns predict high biodiversity in ecosystems, long-term ecological transients, and the possibility of a new type of predator-prey cycles.