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Monitoring Intraspecies Competition in a Bacterial Cell Population by Cocultivation of Fluorescently Labelled Strains
Published on: January 18, 2014
Experimental tests for an evolutionary trade-off between growth rate and yield in E. coli
Maja Novak1, Thomas Pfeiffer, Richard E Lenski
1Institute of Integrative Biology, Eldgenossische Technische Hochschule Zurich, 8092 Zurich, Switzerland. maja.novak@env.ethz.ch
The American Naturalist
|July 29, 2006
Summary
This study investigated the growth rate versus yield trade-off in evolved Escherichia coli populations. While not found between populations, a trade-off was observed within populations, suggesting diverse genetic adaptations.
Area of Science:
- Microbial evolution
- Population genetics
- Metabolic trade-offs
Background:
- Theoretical models predict a trade-off between growth rate and yield in heterotrophic organisms.
- Understanding these trade-offs is crucial for predicting microbial adaptation and evolution under selective pressures.
Purpose of the Study:
- To experimentally test for the predicted trade-off between growth rate and yield in evolved populations of Escherichia coli B.
- To determine if this trade-off exists within populations, between populations, or over evolutionary time.
Main Methods:
- Analyzed growth rate and yield in 12 Escherichia coli B populations evolved for 20,000 generations.
- Performed three tests: temporal analysis within populations, cross-population correlation, and within-population clone analysis.
- Assessed correlations between growth rate and yield across different evolutionary scales.
Main Results:
- No significant trade-off between growth rate and yield was detected when analyzing changes over evolutionary time or across different populations.
- A significant negative correlation between growth rate and yield was observed when analyzing clones within selected populations.
- This within-population trade-off suggests distinct physiological constraints arising from different evolved genetic solutions.
Conclusions:
- The study provides evidence for a growth rate-yield trade-off, but it is most detectable at the within-population level.
- Analysis of within-population diversity is a sensitive method for detecting such trade-offs.
- Evolved populations developed unique genetic strategies, leading to population-specific physiological constraints and trade-offs.
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