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Evolutionary dynamics of pathogen resistance and tolerance.
1Geobotanical Institute, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland. roy@geobot.umnw.ethz.ch
Evolution; International Journal of Organic Evolution
|August 11, 2000
Summary
Host resistance and tolerance to disease have different evolutionary paths. Resistance genes don't become universal, while tolerance genes can spread to fixation, impacting disease dynamics.
Area of Science:
- Evolutionary biology
- Host-pathogen interactions
- Population genetics
Background:
- Organisms combat disease via resistance (limiting infection) or tolerance (mitigating fitness costs).
- Understanding the evolutionary consequences of these distinct strategies is crucial for host-pathogen dynamics.
Purpose of the Study:
- To investigate the differing evolutionary outcomes of resistance versus tolerance strategies in host organisms.
- To determine why diseases persist despite host defense mechanisms.
Main Methods:
- Theoretical modeling of gene spread under selection for resistance and tolerance.
- Analysis of field data on plant resistance and tolerance to rust fungi.
Main Results:
- Genes conferring complete resistance cannot reach fixation due to declining infection rates, limiting disease elimination by natural selection.
- Genes conferring tolerance can reach fixation as increased disease incidence enhances their selective advantage.
- Field data show resistance traits are polymorphic, while tolerance traits are fixed in plant-rust systems.
Conclusions:
- Resistance and tolerance have fundamentally different evolutionary trajectories and population-level outcomes.
- Tolerance provides a potential mechanism for the evolution of mutualism from parasitism.
- These findings help explain the widespread prevalence of infectious diseases in nature.