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Present address: School of Biological Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom.
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Group living and investment in immune defence: an interspecific analysis
Article first published online: 10 FEB 2003
DOI: 10.1046/j.1365-2656.2003.00680.x
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How to Cite
Wilson, K., Knell, R., Boots, M. and Koch-Osborne, J. (2003), Group living and investment in immune defence: an interspecific analysis. Journal of Animal Ecology, 72: 133–143. doi: 10.1046/j.1365-2656.2003.00680.x
Publication History
- Issue published online: 10 FEB 2003
- Article first published online: 10 FEB 2003
- Received 10 June 2002; accepted 18 September 2002
- Abstract
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- Cited By
Keywords:
- aggregation;
- costs of sociality;
- group living;
- immunocompetence;
- infection;
- Lepidoptera;
- pathogen
Summary
- 1Since parasite transmission is often density-dependent, group living is normally thought to lead to an increased exposure to parasitism. As a consequence, it is predicted that animals living in groups will invest more resources (energy, time, risk, etc.) in parasite defence than those living solitarily.
- 2We tested this prediction by measuring basal immune parameters in the larvae of 12 species of Lepidoptera, grouped into six phylogenetically matched species-pairs, each comprising one solitary feeding and one gregariously feeding species.
- 3Contrary to expectation, the solitary species in all six species-pairs had higher total haemocyte counts than the gregarious species, and in five out of six species-pairs the solitary species also exhibited higher phenoloxidase activity. Both measurements were positively correlated with each other and with the magnitude of the cellular encapsulation response.
- 4The relationship between infection risk and group living was investigated with a dynamic, spatially explicit, host–pathogen model. This shows that when individuals aggregate in groups, the per capita risk of infection can be reduced if the lower between-group transmission more than compensates for the higher within-group transmission.
- 5We conclude that the expectation that group living always leads to increased exposure to pathogens and parasites is overly simplistic, and that the specific details of the social system in question will determine if there is increased or decreased exposure to infection.