title: Diversity and disease: community structure drives parasite transmission and host fitness.
abstract: Changes in host diversity and community structure have been linked to disease, but the mechanisms underlying such relationships and their applicability to non-vector-borne disease systems remain conjectural. Here we experimentally investigated how changes in host community structure affected the transmission and pathology of the multi-host parasite Ribeiroia ondatrae, which is a widespread cause of amphibian limb deformities. We exposed larval amphibians to parasites in monospecific or heterospecific communities, and varied host number to differentiate between density- and diversity-mediated effects on transmission. In monospecific communities, exposure to Ribeiroia significantly increased mortality (15%), malformations (40%) and time-to-metamorphosis in toads. However, the presence of tree frogs significantly reduced infection in toads, leading to fewer malformations and higher survival than observed in monospecific communities, providing evidence of parasite-mediated facilitation. Our results suggest that interspecific variation in parasite resistance can inhibit parasite transmission in multi-species communities, reducing infection and pathology in sensitive hosts.
authors.affiliation: Ecology and Evolutionary Biology, University of Colorado, Ramaley N122, Campus Box 334, Boulder, CO 80309, USA. pieter.johnson@colorado.edu
authors.forename: Pieter T J
authors.initials: PT
authors.lastname: Johnson
authors.forename: Richard B
authors.initials: RB
authors.lastname: Hartson
authors.forename: Donald J
authors.initials: DJ
authors.lastname: Larson
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Sutherland
mesh_terms: D000818:Animals; D001001:Anura / Q000002:abnormalities / Q000469:parasitology*; D044822:Biodiversity; D006790:Host-Parasite Interactions; D007814:Larva / Q000469:parasitology; D008675:Metamorphosis, Biological; D011156:Population Density; D011157:Population Dynamics; D012908:Snails / Q000469:parasitology*; D014200:Trematoda / Q000472:pathogenicity*; D014201:Trematode Infections / Q000473:pathology / Q000635:transmission* / Q000662:veterinary