Water temperature, not fish morph, determines parasite infections of sympatric Icelandic threespine sticklebacks (Gasterosteus aculeatus)
Article first published online: 17 APR 2013
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Ecology and Evolution
Volume 3, Issue 6, pages 1507–1517, June 2013
How to Cite
Ecology and Evolution 2013; 3(6): 1507–1517
- Issue published online: 12 JUN 2013
- Article first published online: 17 APR 2013
- Manuscript Accepted: 19 MAR 2013
- Manuscript Revised: 18 MAR 2013
- Manuscript Received: 8 FEB 2013
- Academy of Finland. Grant Numbers: 121993, 259256
- Finnish Academy Centre of Excellence of Evolutionary Research
- Swiss National Science Foundation. Grant Number: 31003A-113666
- Adaptive radiation;
- Diplostomum ;
- ecological speciation;
- habitat specialization;
- host-parasite interactions;
- stickleback morphotypes
Parasite communities of fishes are known to respond directly to the abiotic environment of the host, for example, to water quality and water temperature. Biotic factors are also important as they affect the exposure profile through heterogeneities in parasite distribution in the environment. Parasites in a particular environment may pose a strong selection on fish. For example, ecological differences in selection by parasites have been hypothesized to facilitate evolutionary differentiation of freshwater fish morphs specializing on different food types. However, as parasites may also respond directly to abiotic environment the parasite risk does not depend only on biotic features of the host environment. It is possible that different morphs experience specific selection gradients by parasites but it is not clear how consistent the selection is when abiotic factors change. We examined parasite pressure in sympatric morphs of threespine stickleback (Gasterosteus aculeatus) across a temperature gradient in two large Icelandic lakes, Myvatn and Thingvallavatn. Habitat-specific temperature gradients in these lakes are opposite. Myvatn lava rock morph lives in a warm environment, while the mud morph lives in the cold. In Thingvallavatn, the lava rock morph lives in a cold environment and the mud morph in a warm habitat. We found more parasites in fish living in higher temperature in both lakes, independent of the fish morph, and this pattern was similar for the two dominating parasite taxa, trematodes and cestodes. However, at the same time, we also found higher parasite abundance in a third morph living in deep cold–water habitat in Thingvallavatn compared to the cold-water lava morph, indicating strong effect of habitat-specific biotic factors. Our results suggest complex interactions between water temperature and biotic factors in determining the parasite community structure, a pattern that may have implications for differentiation of stickleback morphs.