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Potential for hitchhiking in the eda-edd-zwf gene cluster of Escherichia coli
Published online by Cambridge University Press: 14 April 2009
Summary
The loci eda, edd and zwf form a tightly linked cluster in E. coli that functions in the metabolism of galacturonate, gluconate and glucose. This cluster has been transferred from six natural isolates into the genetic background of E. coli K12 and examined with regard to effects on growth rate in chemostats. Although the naturally occurring eda and zwf alleles are selectively neutral, the edd alleles are not. The edd alleles fall into three functional classes distinguished by their effects on growth rate in gluconate medium, the most common classes differing in fitness by approximately 1% per hour. This extensive non-neutral genetic variation of edd is discussed in light of the evident rarity of gluconate as a natural substrate. We propose that gluconate selection is intermittent in space or time, providing the population an opportunity to accumulate non-neutral genetic variants during periods of relaxed selection. Such genetic variants will eventually be sorted out by the intermittent periods of gluconate selection, and during these periods the linked eda and zwf alleles will experience pronounced hitchhiking effects.
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- Copyright © Cambridge University Press 1984
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