Predation and disturbance interact to shape prey species diversity

Though predation, productivity (nutrient richness), spatial heterogeneity, and disturbance regimes are known to influence species diversity, interactions between these factors remain largely unknown. Predation has been shown to interact with productivity and with spatial heterogeneity, but few experimental studies have focused on how predation and disturbance interact to influence prey diversity. We used theory and experiments to investigate how these factors influence diversification of Pseudomonas fluorescens by manipulating both predation (presence or absence of Bdellovibrio bacteriovorus) and disturbance (frequency and intensity of disturbance). Our results show that in a homogeneous environment, predation is essential to promote prey species diversity. However, in most but not all treatments, elevated diversity was transitory, implying that the effect of predation on diversity was strongly influenced by disturbance. Both our experimental and theoretical results suggest that disturbance interacts with predation by modifying the interplay of resource and apparent competition among prey.