Rapid evolution and ecological host-parasite dynamics

• Published in: Ecology letters Vol. 10; no. 1; pp. 44 - 53
• Main Authors: Duffy, Meghan A, Sivars-Becker, Lena
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.01.2007; Blackwell Publishing Ltd
• Subjects: Animals; Ascomycota - pathogenicity; Biological Evolution; biological resistance; Controlled natural selection; Daphnia - parasitology; Daphnia dentifera; directional selection; Disease Outbreaks; diversity; Ecology; epidemic fadeout; Genetic Variation; host-parasite coevolution; Host-Parasite Interactions; Immunity, Innate; Metschnikowia bicuspidata; Population Dynamics; rapid evolution; resistance; susceptibility
• ISSN: 1461-023X; 1461-0248
• DOI: 10.1111/j.1461-0248.2006.00995.x

Traditionally, the termination of parasite epidemics has been attributed to ecological causes: namely, the depletion of susceptible hosts as a result of mortality or acquired immunity. Here, we suggest that epidemics can also end because of rapid host evolution. Focusing on a particular host-parasite system, Daphnia dentifera and its parasite Metschnikowia bicuspidata, we show that Daphnia from lakes with recent epidemics were more resistant to infection and had less variance in susceptibility than Daphnia from lakes without recent epidemics. However, our studies revealed little evidence for genetic variation in infectivity or virulence in Metschnikowia. Incorporating the observed genetic variation in host susceptibility into an epidemiological model parameterized for this system reveals that rapid evolution can explain the termination of epidemics on time scales matching what occurs in lake populations. Thus, not only does our study provide rare evidence for parasite-mediated selection in natural populations, it also suggests that rapid evolution has important effects on short-term host-parasite dynamics.