Introduced parasites in food webs: new spades, shifting structures?

Introduction of free-living species also results in co-introduction of their parasites. Since recent advances have shown that native parasites dramatically alter food web structure, I evaluate here how introduced parasites might reorganise food webs. Empirical evidence suggests that introduced parasites alter food webs qualitatively through topological changes and quantitatively through shifts in trophic relationships arising from modified host phenotypic traits. I argue that predicting the extent of food web reorganisation is, however, difficult due to underlying ecological and evolutionary processes that could provide contrasting food web outcomes, including enemy release, biotic resistance, and parasite spillover and spillback. Nevertheless, I suggest these food web reorganisations represent a further aspect of human-mediated global change resulting in irreversible consequences across multiple trophic levels.