Predation shifts coevolution toward higher host contact rate and parasite virulence

Jason C. Walsman, Clayton E. Cressler

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


Hosts can avoid parasites (and pathogens) by reducing social contact, but such isolation may carry costs, e.g. increased vulnerability to predators. Thus, many predator-host-parasite systems confront hosts with a trade-off between predation and parasitism. Parasites, meanwhile, evolve higher virulence in response to increased host sociality and consequently, increased multiple infections. How does predation shift coevolution of host behaviour and parasite virulenceWhat if predators are selective, i.e. predators disproportionately capture the sickest hosts We answer these questions with an eco-coevolutionary model parametrized for a Trinidadian guppy-Gyrodactylus spp. system. Here, increased predation drives host coevolution of higher grouping, which selects for higher virulence. Additionally, higher predator selectivity drives the contact rate higher and virulence lower. Finally, we show how predation and selectivity can have very different impacts on host density and prevalence depending on whether hosts or parasites evolve, or both. For example, higher predator selectivity led to lower prevalence with no evolution or only parasite evolution but higher prevalence with host evolution or coevolution. These findings inform our understanding of diverse systems in which host behavioural responses to predation may lead to increased prevalence and virulence of parasites.

Original languageEnglish (US)
Article number20212800
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1978
StatePublished - Jul 13 2022
Externally publishedYes


  • eco-evolutionary modelling
  • group living
  • host-parasite coevolution
  • parasite avoidance
  • predator-prey
  • social behaviour

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Environmental Science(all)
  • Agricultural and Biological Sciences(all)


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