Evolutionary Ecology

, Volume 7, Issue 1, pp 45–75

Coevolutionary genetics of plants and pathogens

  • Steven A. Frank

DOI: 10.1007/BF01237734

Cite this article as:
Frank, S.A. Evol Ecol (1993) 7: 45. doi:10.1007/BF01237734


The genetic polymorphism maintained by host-pathogen coevolution is analysed in a multilocus model. The model assumes gene-for-gene interactions of the type commonly observed between host plants and their fungal pathogens. Unstable (epidemic) systems maintain more resistance genes, fewer virulence genes, and less overall genetic diversity than stable (endemic) diseases. The stability of the system depends primarily on demographic parameters, such as the pathogen's intrinsic rate of increase, rather than genetic parameters, such as the costs of resistance and virulence. At equilibrium the model predicts that the number of resistance alleles in each host plant follows a binomial distribution that depends on the cost to the pathogen for carrying virulence alleles. Similarly, the number of virulence alleles in each pathogen spore follows a binomial distribution that depends on one minus the cost to the host for carrying resistance alleles. Data from wild populations match the predicted binomial distributions.


plant disease genetic polymorphism gene-for-gene epidemiology 

Copyright information

© Chapman & Hall 1993

Authors and Affiliations

  • Steven A. Frank
    • 1
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of CaliforniaIrvineUSA

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