Accepted:
01 Nov 2000
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/vol08/bowers01/ | © Copyright 2001 | |||
| Volume 08 | Received: Accepted: |
15 Jul 2000 01 Nov 2000 |
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Community dynamics, invasion criteria and the co-evolution of host and pathogen
Bowers, R. G. |
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| Abstract | |
| The basic reproduction ratio R0 - the expected number of secondary cases per primary in a totally susceptible population - occupies a central position in the theory of host-pathogen interactions. The baseline criterion for the evolution of pathogen virulence (against the background of a fixed host) is that virulence evolves to maximise R0. Recently, an additional, more host-centred characterisation of host-pathogen systems, using the basic depression ratio D0, has been introduced. This quantity is the number of host individuals per infected by which the infected host population is depressed below its uninfected level. The baseline criterion for the evolution of host resistance to microparasites (against the background of a fixed pathogen) is that resistance evolves to minimise D0. Here, we discuss the community dynamics of the co-evolution of host and pathogen and show how the two extremum principles mentioned above interact. We use invadability criteria to distinguish circumstances in which a rare invading host or pathogen strain prospers from those where it does not. We show how a game-theoretic interpretation of the properties of the equilibrium states of the dynamical model emerges naturally. We distinguish criteria under which there are, first, unique winning host and pathogen strains and, second, strain coexistence. We discuss how intermediate values of certain parameters - favoured at different extremes by host and pathogen - are likely to be preferred. Areas for future work include, first, the role of trade-offs between underlying parameters and, second, the more detailed investigation of the relation between the dynamics and the emergent game-theoretic picture. | |
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Multimedia Links (none) Reference Links (none) Citation Reference Bowers, R. G. (2000), Community dynamics, invasion criteria and the co-evolution of host and pathogen, Complexity International, Volume 08, Paper ID: bowers01, URL: http://www.complexity.org.au/ci/vol08/bowers01/ |
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