title: Is a healthy ecosystem one that is rich in parasites?
abstract: Historically, the role of parasites in ecosystem functioning has been considered trivial because a cursory examination reveals that their relative biomass is low compared with that of other trophic groups. However there is increasing evidence that parasite-mediated effects could be significant: they shape host population dynamics, alter interspecific competition, influence energy flow and appear to be important drivers of biodiversity. Indeed they influence a range of ecosystem functions and have a major effect on the structure of some food webs. Here, we consider the bottom-up and top-down processes of how parasitism influences ecosystem functioning and show that there is evidence that parasites are important for biodiversity and production; thus, we consider a healthy system to be one that is rich in parasite species.
authors.affiliation: Center for Infectious Disease Dynamics, Penn State University, University Park, PA 16802, USA. pjh18@psu.edu
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Hudson
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Dobson
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Lafferty
mesh_terms: D000818:Animals; D044822:Biodiversity; D017753:Ecosystem; D019143:Evolution, Molecular; D020387:Food Chain; D006262:Health; D006790:Host-Parasite Interactions / Q000502:physiology*; D010271:Parasites / Q000502:physiology*