Host immunization shapes interspecific associations in trematode parasites
Article first published online: 11 MAY 2009
© 2009 The Authors. Journal compilation © 2009 British Ecological Society
Journal of Animal Ecology
Volume 78, Issue 5, pages 945–952, September 2009
How to Cite
Karvonen, A., Seppälä, O. and Tellervo Valtonen, E. (2009), Host immunization shapes interspecific associations in trematode parasites. Journal of Animal Ecology, 78: 945–952. doi: 10.1111/j.1365-2656.2009.01562.x
- Issue published online: 29 JUL 2009
- Article first published online: 11 MAY 2009
- Received 27 November 2008; accepted 10 April 2009; Handling Editor: Charlie Nunn
- community ecology;
- host–parasite interactions;
- multiple infection;
1. Individuals of free-living organisms are commonly infected by multiple parasite species. Under such circumstances, positive or negative associations between the species are possible because of direct or indirect interactions, details in parasite transmission ecology and host-mediated factors. One possible mechanism underlying these processes is host immunity, but its role in shaping these associations has rarely been tackled experimentally.
2. In this study, we tested the effect of host immunization on associations between trematode parasites infecting eyes of fish. We first analysed the associations between three species (Diplostomum spathaceum, Diplostomum gasterostei and Tylodelphys clavata) in wild hosts, roach (Rutilus rutilus) and perch (Perca fluviatilis). Second, using rainbow trout (Oncorhynchus mykiss) as a model fish species, we experimentally investigated how sequential immunization of the host (i.e. one parasite species infects and immunizes the host first) could affect the associations between two of the species.
3. The results indicated that most of the associations were positive in wild hosts, which supports between-individual variation in host susceptibility, rather than competitive exclusion between the parasite species. However, positive associations were more common in roach than in perch, possibly reflecting differences in ecological conditions of exposure between the host species. The experimental data showed that positive associations between two of the species were eroded by host immunization against one of the parasite species.
4. We conclude that sequential immunization of hosts has a marked effect on interspecific parasite associations and basically can determine if positive associations are detected or not. This implies that correlative results suggesting non-interactive community structure in general may be obscured by the sequence of previous parasite exposure and corresponding dynamics of host immunization.