Patterns of multiparasitism and consequences of co-infection in fathead minnows (Pimephales promelas)

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Hirtle, Sarah Valerie
University of Lethbridge. Faculty of Arts and Science
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Lethbridge, Alta. : University of Lethbridge, Dept. of Biological Sciences
Individual hosts are often infected with multiple parasite species or strains simultaneously. Co-occurring parasites can profoundly impact each other and their hosts via interspecific interactions. To further our understanding of co-infection in wildlife, I censused the parasite communities of fathead minnows (Pimephales promelas) from southern Alberta over three years. Nearly all minnows were co-infected, and the larval trematodes Ornithodiplostomum ptychocheilus and Ornithodiplostomum sp. co-occurred more frequently than expected by chance. I exposed minnows to cercariae of these species to evaluate the effects of intensity dependence and co-infection on parasite development. While negative intensity-dependent growth occurred only for O. ptychocheilus, both species were significantly smaller post-encystment in co-infections than in mono-infections. Thus, Ornithodiplostomum spp. development is influenced by conspecifics and heterospecifics. Taken together, my results suggest that naturally co-occurring parasites in spatially segregated infection sites can influence one another’s growth within their shared intermediate host, with possible ecological and evolutionary consequences.
ecology , parasitology , co-infection , parasitism , host-parasite interactions , trematoda , biodiversity , multiparasitism , multi-species infection , fish parasites , Fathead minnow--Parasites--Research , Fishes--Parasites , Parasites--Behavior--Research , Parasites--Ecology--Research , Host-parasite relationships , Trematoda--Research , Ecology , Parasitology , Parasitism , Biodiversity , Dissertations, Academic