PARASITE CO-TRANSMISSION AND THE EVOLUTIONARY EPIDEMIOLOGY OF VIRULENCE
Article first published online: 16 NOV 2012
© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.
Volume 67, Issue 4, pages 921–933, April 2013
How to Cite
Alizon, S. (2013), PARASITE CO-TRANSMISSION AND THE EVOLUTIONARY EPIDEMIOLOGY OF VIRULENCE. Evolution, 67: 921–933. doi: 10.1111/j.1558-5646.2012.01827.x
- Issue published online: 3 APR 2013
- Article first published online: 16 NOV 2012
- Accepted manuscript online: 22 OCT 2012 08:45AM EST
- Received July 19, 2012 Accepted September 25, 2012
- multiple infections;
Hosts are often co-infected by several parasite genotypes of the same species or even by different species and this is known to affect virulence evolution. However, epidemiological models typically assume that only one of the co-infecting strains can be transmitted at the same time, which is often at odds with the observed biology. Here, I study the effect of co-transmission on virulence evolution in a case where parasites compete for host resources. For co-infections by strains of the same species, increased co-transmission selects for less virulent strains. This is because co-transmission aligns the interests of co-infecting strains, thus decreasing the selective pressure for increased within-host competitiveness. For co-infection caused by different parasite species, the evolutionary outcome depends on the respective virulence of the two parasite species. Finally, I investigate asymmetric scenarios, for example that of plant viruses that require “helper” molecules produced by viruses from another species to be transmitted. These results show that even if parasite strains compete for host resources, the prevalence of co-infections can be a poor predictor of virulence evolution.