Success, failure and ambiguity of the dilution effect among competitors

Alexander T. Strauss, David J. Civitello, Carla E. Cáceres, Spencer R. Hall

Research output: Contribution to journalArticlepeer-review


It remains challenging to predict variation in the magnitude of disease outbreaks. The dilution effect seeks to explain this variation by linking multiple host species to disease transmission. It predicts that disease risk increases for a focal host when host species diversity declines. However, when an increase in species diversity does not reduce disease, we are often unable to diagnose why. Here, we increase mechanistic and predictive clarity of the dilution effect with a general trait-based model of disease transmission in multi-host communities. Then, we parameterise and empirically test our model with a multi-generational case study of planktonic disease. The model-experiment combination shows that hosts that vary in competitive ability (R*) and potential to spread disease (R0) can produce three qualitatively disparate outcomes of dilution on disease: the dilution effect can succeed, fail, or be ambiguous/irrelevant.

Original languageEnglish (US)
Pages (from-to)916-926
Number of pages11
JournalEcology Letters
Issue number9
StatePublished - Sep 1 2015


  • Amplification
  • Daphnia
  • Dilution effect
  • Disease ecology
  • Epidemic
  • Friendly competition
  • Modelling
  • Transmission

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics


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