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Experimental Tests for an Evolutionary Trade‐Off between Growth Rate and Yield in E. coli
Maja Novak, Thomas Pfeiffer, Richard E. Lenski, Uwe Sauer and Sebastian Bonhoeffer
The American Naturalist
Vol. 168, No. 2 (August 2006), pp. 242-251
Stable URL: http://www.jstor.org/stable/10.1086/506527
Page Count: 10
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Abstract: Theoretical studies have predicted a trade‐off between growth rate and yield in heterotrophic organisms. Here we test for the existence of this trade‐off by analyzing the growth characteristics of 12 E. coli B populations that evolved for 20,000 generations under a constant selection regime. We performed three different tests. First, we analyzed changes in growth rate and yield over evolutionary time for each population. Second, we tested for a negative correlation between rate and yield across the 12 populations. Finally, we isolated clones from four selected populations and tested for a negative correlation between rate and yield within these populations. We did not find evidence for a trade‐off based on the first two tests. However, we did observe a trade‐off based on the within‐population correlation of yield and rate. Our results indicate that, at least for the populations studied here, an analysis of the within‐population diversity might be the most sensitive test for the existence of a trade‐off. The observation of a trade‐off within, but not between, populations suggests that the populations evolved different genetic solutions for growth in the selective environment, which in turn led to different physiological constraints.
© 2006 by The University of Chicago.