Parasitism in early life: environmental conditions shape within-brood variation in responses to infection

Granroth-Wilding, H. M.V., Burthe, S. J., Lewis, S., Reed, T. E., Herborn, K. A., Newell, M. A., Takahashi, E. A., Daunt, F. and Cunningham, E. J. (2014) Parasitism in early life: environmental conditions shape within-brood variation in responses to infection. Ecology and Evolution, 4(17), pp. 3408-3419. (doi: 10.1002/ece3.1192)

Abstract

Parasites play key ecological and evolutionary roles through the costs they impose on their host. In wild populations, the effect of parasitism is likely to vary considerably with environmental conditions, which may affect the availability of resources to hosts for defense. However, the interaction between parasitism and prevailing conditions is rarely quantified. In addition to environmental variation acting on hosts, individuals are likely to vary in their response to parasitism, and the combined effect of both may increase heterogeneity in host responses. Offspring hierarchies, established by parents in response to uncertain rearing conditions, may be an important source of variation between individuals. Here, we use experimental antiparasite treatment across 5 years of variable conditions to test how annual population productivity (a proxy for environmental conditions) and parasitism interact to affect growth and survival of different brood members in juvenile European shags (Phalacrocorax aristotelis). In control broods, last-hatched chicks had more plastic growth rates, growing faster in more productive years. Older siblings grew at a similar rate in all years. Treatment removed the effect of environment on last-hatched chicks, such that all siblings in treated broods grew at a similar rate across environmental conditions. There were no differences in nematode burden between years or siblings, suggesting that variation in responses arose from intrinsic differences between chicks. Whole-brood growth rate was not affected by treatment, indicating that within-brood differences were driven by a change in resource allocation between siblings rather than a change in overall parental provisioning. We show that gastrointestinal parasites can be a key component of offspring's developmental environment. Our results also demonstrate the value of considering prevailing conditions for our understanding of parasite effects on host life-history traits. Establishing how environmental conditions shape responses to parasitism is important as environmental variability is predicted to increase.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Herborn, Dr Katherine
• Authors: Granroth-Wilding, H. M.V., Burthe, S. J., Lewis, S., Reed, T. E., Herborn, K. A., Newell, M. A., Takahashi, E. A., Daunt, F., and Cunningham, E. J.
• College/School: College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
• Journal Name: Ecology and Evolution
• Publisher: John Wiley & Sons Ltd.
• ISSN: 2045-7758
• ISSN (Online): 2045-7758
• Copyright Holders: Copyright © 2014 The Authors
• First Published: First published in Ecology and Evolution 4(17):3408-3419
• Publisher Policy: Reproduced under a Creative Commons License

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