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Antagonistic selection from predators and pathogens alters food-web structure

Edeline, Eric; Ari, Tamara Ben; Vollestad, L. Asbjorn; Winfield, Ian J.; Fletcher, Janice M.; James, J. Ben; Stenseth, Nils C.. 2008 Antagonistic selection from predators and pathogens alters food-web structure. Proceedings of the National Academy of Sciences of the USA, 105 (50). 19792-19796. 10.1073/pnas.0808011105

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Abstract/Summary

Selection can alter predator-prey interactions. However, whether and how complex food-webs respond to selection remain largely unknown. We show in the field that antagonistic selection from predators and pathogens on prey body-size can be a primary driver of food-web functioning. In Windermere, U.K., pike (Esox lucius, the predator) selected against small perch (Perca fluviatilis, the prey), while a perch-specific pathogen selected against large perch. The strongest selective force drove perch trait change and ultimately determined the structure of trophic interactions. Before 1976, the strength of pike-induced selection overrode the strength of pathogen-induced selection and drove a change to larger, faster growing perch. Predation-driven increase in the proportion of large, infection-vulnerable perch presumably favored the pathogen since a peak in the predation pressure in 1976 coincided with pathogen expansion and a massive perch kill. After 1976, the strength of pathogen-induced selection overrode the strength of predator-induced selection and drove a rapid change to smaller, slower growing perch. These changes made perch easier prey for pike and weaker competitors against juvenile pike, ultimately increasing juvenile pike survival and total pike numbers. Therefore, although predators and pathogens exploited the same prey in Windermere, they did not operate competitively but synergistically by driving rapid prey trait change in opposite directions. Our study empirically demonstrates that a consideration of the relative strengths and directions of multiple selective pressures is needed to fully understand community functioning in nature.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1073/pnas.0808011105
Programmes: CEH Programmes pre-2009 publications > Water > WA02 Quantifying processes that link water quality and quantity, biota and physical environment > WA02.4 Biological interactions
CEH Sections: Parr
Additional Information. Not used in RCUK Gateway to Research.: The definitive version of this paper is available at http://www.pnas.org/
Additional Keywords: cost of immunity, intraguild predation, life history trade-offs, rapid evolution, trait-mediated indirect interactions
NORA Subject Terms: Ecology and Environment
Date made live: 17 Dec 2008 14:28
URI: http://nora.nerc.ac.uk/id/eprint/3092

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