Chapter 23: Evolution of Genetic Systems: Figure P23.6 - (<i>Upper curve</i>) How fitness decreases with the number of deleterious mutations, as in Figure P23.2.

Figure P23.6

Figure P23.6. (Upper curve) How fitness decreases with the number of deleterious mutations, as in Figure P23.2. (Bell-shaped curve) Distribution of the number of deleterious mutations at equilibrium with U = 2. (Dashed line) Equilibrium mean fitness, at exp(–0.5) = 0.61; (solid line) tangent to the upper curve, and so its slope gives the selection coefficient against deleterious mutations, s = 0.01. Because the mean number of deleterious mutations is U/s, the distance between the dashed line and the intercept of the tangent equals U, which here equals 2. (The vertical scale is logarithmic, and so the distance between 0.1 and 1 [say] is log_e(10) = 2.30.)

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