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Evolution of Competitive Ability in Escherichia coli
Daniel Dykhuizen and Daniel Hartl
Vol. 35, No. 3 (May, 1981), pp. 581-594
Published by: Society for the Study of Evolution
Stable URL: http://www.jstor.org/stable/2408204
Page Count: 14
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Chemostats were maintained at generation times of 2.5 h and 5.0 h for 500 h. Every hundred hours samples of the populations were taken, grown up and frozen. These frozen cultures could then be used to measure the relative fitness of different samples by mixing populations together and observing the changes in frequency over time. This experimental procedure allowed us to show the following: 1) The Monod equations for competition in chemostats are quantitatively fair but by no means perfect, as the assimilation parameter is affected by dilution rate. 2) Most of the increase in fitness of a population occurs in the first 200 h, and most of the increased fitness is due to reductions in the assimilation parameter. 3) The fitness increase in populations in replicate chemostats is remarkably parallel. 4) On the average, only 10% or less of the fitness increase in chemostats is due to adaptation to the particular generation time.
Evolution © 1981 Society for the Study of Evolution