Present address: Ritchard B. Hitchman, School of Biological and Molecular Sciences, Oxford Brookes University, Headington Campus, Gipsy Lane, Oxford, OX3 0BP, UK.
Host ecology determines the relative fitness of virus genotypes in mixed-genotype nucleopolyhedrovirus infections
Article first published online: 9 JUL 2004
Journal of Evolutionary Biology
Volume 17, Issue 5, pages 1018–1025, September 2004
How to Cite
Hodgson, D. J., Hitchman, R. B., Vanbergen, A. J., Hails, R. S., Possee, R. D. and Cory, J. S. (2004), Host ecology determines the relative fitness of virus genotypes in mixed-genotype nucleopolyhedrovirus infections. Journal of Evolutionary Biology, 17: 1018–1025. doi: 10.1111/j.1420-9101.2004.00750.x
- Issue published online: 9 JUL 2004
- Article first published online: 9 JUL 2004
- Received 7 January 2004; revised 17 March 2004; accepted 25 March 2004
- differential selection;
- host ecology;
- mixed infection;
- Panolis flammea;
- resource partitioning;
Mixed-genotype infections are common in many natural host–parasite interactions. Classical kin-selection models predict that single-genotype infections can exploit host resources prudently to maximize fitness, but that selection favours rapid exploitation when co-infecting genotypes share limited host resources. However, theory has outpaced evidence: we require empirical studies of pathogen genotypes that naturally co-infect hosts. Do genotypes actually compete within hosts? Can host ecology affect the outcome of co-infection? We posed both questions by comparing traits of infections in which two baculovirus genotypes were fed to hosts alongside inocula of the same or a different genotype. The host, Panolis flammea, is a herbivore of Pinus sylvestris and Pi. contorta. The pathogen, PfNPV (a nucleopolyhedrovirus), occurs naturally as mixtures of genotypes that differ, when isolated, in pathogenicity, speed of kill and yield. Single-genotype infection traits failed to predict the ‘winning’ genotypes in co-infections. Co-infections infected and caused lethal disease in more hosts, and produced high yields, relative to single-genotype infections. The need to share with nonkin did not cause fitness costs to either genotype. In fact, in hosts feeding on Pi. sylvestris, one genotype gained increased yields in mixed-genotype infections. These results are discussed in relation to theory surrounding adaptive responses to competition with nonkin for limited resources.