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Ecol Lett. 2015 Jul;18(7):660-7. doi: 10.1111/ele.12444. Epub 2015 May 18.

Social living mitigates the costs of a chronic illness in a cooperative carnivore.

Author information

1
Department of Biology, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA.
2
US Geological Survey, Northern Rocky Mountain Science Center, Bozeman, MT, USA.
3
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA.
4
Santa Fe Institute, Santa Fe, NM, USA.
5
Yellowstone Wolf Project, Yellowstone National Park, WY, USA.
6
College of Forestry and Conservation, University of Montana, Missoula, MT, USA.

Abstract

Infection risk is assumed to increase with social group size, and thus be a cost of group living. We assess infection risk and costs with respect to group size using data from an epidemic of sarcoptic mange (Sarcoptes scabiei) among grey wolves (Canis lupus). We demonstrate that group size does not predict infection risk and that individual costs of infection, in terms of reduced survival, can be entirely offset by having sufficient numbers of pack-mates. Infected individuals experience increased mortality hazards with increasing proportions of infected pack-mates, but healthy individuals remain unaffected. The social support of group hunting and territory defence are two possible mechanisms mediating infection costs. This is likely a common phenomenon among other social species and chronic infections, but difficult to detect in systems where infection status cannot be measured continuously over time.

KEYWORDS:

Grey wolf; infection costs; infection risk; parasite; sarcoptic mange; social immunity; sociality

PMID:
25983011
PMCID:
PMC4676290
DOI:
10.1111/ele.12444
[Indexed for MEDLINE]
Free PMC Article

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