Some relations between different characteristics of selection
Consider the action of selection with fitness w(x) on a quantitative trait x. What selection, among those that produce the same value of selection differential, leads to minimal values of (a) genetic load, (b) variance of the relative fitness, and (c) variance of the trait after selection? We have shown that for (a) and (c) the answer is strict truncation, whereas for (b) the answer is linear selection. The results for (a) and (b) are true for any selection, while the result for (c) is true only for directional selection. Implications of these findings are discussed.