The effect of a pathogen epidemic on the genetic structure and reproductive strategy of the crustacean Daphnia magna

Suzanne E. Mitchell, Andrew F. Read, Tom J. Little

Research output: Contribution to journalArticle

47 Scopus citations

Abstract

Host-parasite coevolution is potentially of great importance in producing and maintaining biological diversity. However, there is a lack of evidence for parasites directly driving genetic change. We examined the impact of an epidemic of the bacterium Pasteuria ramosa on a natural population of the crustacean Daphnia magna through the use of molecular markers (allozymes) and laboratory experiments to determine the susceptibility of hosts collected during and after the epidemic. Some allozyme genotypes were more heavily infected than others in field samples, and the population genetic structure differed during and after the epidemic, consistent with a response to parasite-mediated selection. Laboratory studies showed no evidence for the evolution of higher resistance, but did reveal an intriguing life-history pattern: host genotypes that were more susceptible also showed a greater tendency to engage in sex. In light of this, we suggest a model of host-parasite dynamics that incorporates the cycles of sex and parthenogenesis that Daphnia undergo in the field.

Original languageEnglish (US)
Pages (from-to)848-858
Number of pages11
JournalEcology Letters
Volume7
Issue number9
DOIs
StatePublished - Sep 1 2004

All Science Journal Classification (ASJC) codes

  • Ecology, Evolution, Behavior and Systematics

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