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Variation in the risk of being wounded: an overlooked factor in studies of invertebrate immune function?


*Correspondence: E-mail: Present addresses: S. J. Plaistow, Department of Biological Sciences, University of Stirling, Stirling FK9 4LA, UK Y. Outreman, UMR ENSAR/INRA BiO3P, 65 rue de Saint-Brieuc, CS 84215, 35042 Rennes Cedex, France Y. Moret, Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK


In invertebrates, wounding can trigger an immune response, and will often expose organisms to parasites and pathogens. Here we show that in the amphipod Gammarus pulex, wounding abundance is negatively correlated with PhenolOxidase activity (a major component of the invertebrate immune response), and that the occurrence and abundance of wounding is extremely high and varies significantly between five natural populations. In some populations the prevalence and abundance of wounds also varied between sexes. Given that, using and maintaining an efficient immune system is costly, we suggest that the frequency of wounding may be an important selective pressure influencing an organism's optimal investment in immune defences.