Parasitism and the Biodiversity-Functioning Relationship

Abstract

Species interactions can influence ecosystem functioning by enhancing or suppressing the activities of species that drive ecosystem processes, or by causing changes in biodiversity. However, one important class of species interactions - parasitism - has been little considered in biodiversity and ecosystem functioning (BD-EF) research. Parasites might increase or decrease ecosystem processes by reducing host abundance. Parasites could also increase trait diversity by suppressing dominant species or by increasing within-host trait diversity. These different mechanisms by which parasites might affect ecosystem function pose challenges in predicting their net effects. Nonetheless, given the ubiquity of parasites, we propose that parasite-host interactions should be incorporated into the BD-EF framework.

Parasitization of bats by bat flies (Streblidae) in fragmented habitats

“…Parasites are highly speciose, with species numbers approaching the number of free‐living species (Price, ; Windsor, ). Parasites can affect their hosts in many ways, inducing regulative negative feedback loops that maintain the stability and integrity of ecosystems and contribute to ecosystem functioning (Brooks & Hoberg, ; Frainer, McKie, Amundsen, Knudsen, & Lafferty, ; Hudson, ). Among other functions, parasites may control host population sizes (Anderson & May, ) by reducing reproduction, increasing predation risk, and even altering host morphology and mating behavior (Frainer et al, ).…”

“…Parasites can affect their hosts in many ways, inducing regulative negative feedback loops that maintain the stability and integrity of ecosystems and contribute to ecosystem functioning (Brooks & Hoberg, ; Frainer, McKie, Amundsen, Knudsen, & Lafferty, ; Hudson, ). Among other functions, parasites may control host population sizes (Anderson & May, ) by reducing reproduction, increasing predation risk, and even altering host morphology and mating behavior (Frainer et al, ). In spite of their ecological importance, few parasite taxa have been studied in detail, while for most groups estimates of parasite species richness and diversity are lacking (Poulin, ).…”

Parasite and pathogen effects on ecosystem processes: A quantitative review

“…, Frainer et al. ). We hypothesize that pathogen effects are greater in ecosystems where the period of coevolution with pathogen has been shorter, as for example in novel urban, silvicultural, and agricultural ecosystems, or where invasive species are involved, and that disturbance and pathogens can have synergistic effects.…”

“…To develop a predictive framework thus requires host, pathogen, and ecosystem trait data (Schmitz , Frainer et al. ). Our results indicate that some of these data exist in published studies, while some likely need to be gathered, through observational studies replicated across ecosystems, as well as large‐scale field manipulations of pathogens, as also recommended in a recent review (Preston et al.…”

“…, Frainer et al. ), to our knowledge, these effects have not been quantified across taxa, ecosystems, and ecosystem processes. Quantitative syntheses are needed to estimate relative impacts and prioritize research directions.…”