Predicting invasive species impacts: a community module functional response approach reveals context dependencies

1. Predatory functional responses play integral roles in predator-prey dynamics, and their assessment promises greater understanding and prediction of the predatory impacts of invasive species. 2. Other inter-specific interactions, however, such as parasitism and higher-order predation, have the potential to modify predator-prey interactions and thus the predictive capability of the comparative functional response approach. 3. We used a four-species community module (higher-order predator; focal native or invasive predators; parasites of focal predators; native prey) to compare the predatory functional responses of native Gammarus duebeni celticus and invasive Gammarus pulex amphipods towards three invertebrate prey species (Asellus aquaticus, Simulium spp., Baetis rhodani), thus quantifying the context dependencies of parasitism and a higher-order fish predator on these functional responses. 4. Our functional response experiments demonstrated that the invasive amphipod had a higher pre...