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Standing genetic variation in host preference for mutualist microbial symbionts
Anna K Simonsen1, John R Stinchcombe2
1Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, Canada M5S 3B2 anna.simonsen@gmail.ca.
Proceedings. Biological Sciences
|October 31, 2014
Summary
Legume plants can genetically favor beneficial microbes over harmful ones, showing that mutualisms can adapt to prevent exploitation. This microbial preference is heritable and under natural selection, ensuring symbiotic stability.
Area of Science:
- Ecology
- Evolutionary Biology
- Plant-Microbe Interactions
Background:
- Mutualisms, beneficial symbiotic relationships, can be unstable if hosts associate with exploitative microbes.
- Limited empirical evidence exists on how mutualism-stabilizing mechanisms evolve under exploitation pressure.
Purpose of the Study:
- To investigate quantitative genetic variation in legume host responses to mutualistic versus exploitative rhizobia.
- To determine if selection favors preferential associations with mutualistic symbionts over exploitative ones.
Main Methods:
- Utilized a model system: the interaction between legumes and nitrogen-fixing rhizobia.
- Conducted controlled greenhouse experiments to assess plant responses to different rhizobia types.
- Analyzed for genetic variation and selection on host traits related to symbiont preference.
Main Results:
- Significant heritability was found in legume hosts' ability to preferentially associate with mutualistic rhizobia over exploitative ones.
- Evidence of selection favoring a reduction in associations with exploitative rhizobia was detected.
- No evidence suggested selection would favor the loss of these stabilizing mechanisms in the absence of exploitation.
Conclusions:
- Genetic variation exists in host mechanisms that stabilize mutualisms by preferential association.
- These traits are under selection, indicating potential for micro-evolutionary adaptation in natural populations facing evolving microbial partners.
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