A molecular investigation of genotype by environment interactions

Examination of the fitness of seven naturally occurring variants of the lactose operon of Escherichia coli during competition for growth rate-limiting quantities of galactosyl-glycerol reveals that environment interactions lead to the occurrence of marked genotype, while changes in the fitness by these interactions are rare. Larger control coefficients of the permease and beta-galactosidase are responsible for the larger selection coefficients on the artificial galactosides. Novel environments do not lead to great selection intensities, as suggested by the flux summation theorem.