Figure P23.9

Figure P23.9. Fitness as a function of enzyme concentration, E/X, measured relative to substrate concentration (the production cost is not included here). (Rightmost red dot) Optimal enzyme concentration for a low cost (βX = 0.01); (leftmost red dot) half this value, as for a heterozygote for a loss-of-function allele. (Blue dots) Same, but for a high cost (βX = 0.5).