Population Studies in Escherichia coli : Selection for Lactose Utilization

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概要

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• Competition experiments were conducted between twe genotypes of E.coli K-12 [lac^+(G_0) and lac^-(G_1)], grown on four different culture media differing in the concentration of lactose. Trajectories of gene frequency and population size followed for the various mixed populations. In almost all cases, the lac^- genotype (G_1) were replaced by the lac^+ genotype (G_0), even when no lactose was present in the medium. The selective differential and the rate of "gene substitution" were increasing functions of lactose concentration, as expected, and the selective differentials were found to be density-dependent and frequency-independent. One culture established a persistent polymorphism, with population size greater than that of either monomorphic control. Evolution in this culture, by means of successive substitutions of more efficient G_0 and G_1 derivatives resulted in minor changes in gene frequency, and a sort of complementation of the two genotypes. These experiments suggest that the more efficient genotype will prevail, except where a mixture is more efficient than either genotype alone.

• 城西大学の論文

著者

• Kosuda Kazuhiko

  Josai University

• Smouse Peter

  Michigan University

関連論文

• Population Studies in Escherichia coli : Selection for Lactose Utilization

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