Fitness consequences of immune responses: strengthening the empirical framework for ecoimmunology
Article first published online: 23 SEP 2010
© 2010 The Authors. Functional Ecology © 2010 British Ecological Society
Special Issue: ECOLOGICAL IMMUNOLOGY
Volume 25, Issue 1, pages 5–17, February 2011
How to Cite
Graham, A. L., Shuker, D. M., Pollitt, L. C., Auld, S. K. J. R., Wilson, A. J. and Little, T. J. (2011), Fitness consequences of immune responses: strengthening the empirical framework for ecoimmunology. Functional Ecology, 25: 5–17. doi: 10.1111/j.1365-2435.2010.01777.x
- Issue published online: 21 JAN 2011
- Article first published online: 23 SEP 2010
- Received 17 February 2010; accepted 12 August 2010Handling Editor: Lynn Martin
- bivariate statistics;
- evolutionary parasitology;
- optimal immunity;
- random regression;
1. Ecoimmunologists aim to understand the costs, benefits, and net fitness consequences of different strategies for immune defense.
2. Measuring the fitness consequences of immune responses is difficult, partly because of complex relationships between host fitness and the within-host density of parasites and immunological cells or molecules. In particular, neither the strongest immune responses nor the lowest parasite densities necessarily maximize host fitness.
3. Here, we propose that ecoimmunologists should routinely endeavour to measure three intertwined parameters: host fitness, parasite density, and relevant immune responses. We further propose that analyses of relationships among these traits would benefit from the statistical machinery used for analyses of phenotypic plasticity and/or methods that are robust to the bi-directional causation inherent in host-parasite relationships. For example, analyses of how host fitness depends upon parasite density, which is an evolutionary ecological definition of tolerance, would benefit from these more robust methods.
4. Together, these steps promote rigorous quantification of the fitness consequences of immune responses. Such quantification is essential if ecoimmunologists are to decipher causes of immune polymorphism in nature and predict trajectories of natural selection on immune defense.