Fig. 1

Expected rate of change per generation (R′) for a single selected trait under direct selection, expressed in phenotypic standard deviation units, for different values of heritability (h ²) and different selection intensities (i). Assuming a Gaussian distribution of the trait, elimination of 25, 50 or 75 % of the population corresponds to values of i = 0.42, 0.80 or 1.27, respectively. The range of empirical values of R′ found in the literature by Gingerich (2009) lies between the dotted lines