Table 4 Response to selection applied only to males or females, or to all individuals, in terms of the change in the frequency of the A1 allele in the offspring (Δpt), and the change in the population mean phenotype in the offspring (Embedded Image) and grand-offspring (Embedded Image) of the generation in which selection is imposed (which is generation t−1)
Target of selection (generation t−1)Change in frequency of A1 allele (Δpt)Response in offspring (Embedded Image)Response in grand−offspring (Embedded Image)Total response Embedded Image
FemalespqEmbedded Image(VA − covA,O (all))/2Embedded Image =Vh(dams)/2Embedded ImagecovA,O (all)/2Embedded ImageVA/2Embedded Image
MalespqEmbedded Image/Embedded Image(VA + covA,O (all))/2Embedded Image =Vh(sires)/2Embedded Image−covA,O (all)/2Embedded ImageVA/2Embedded Image
AllpqEmbedded Image/Embedded ImageVA/Embedded Image0VA/Embedded Image
  • In all cases, the response is in comparison to the previous generation (i.e., offspring vs. their parents). We assume that selection is applied to adults prior to reproduction, such that the allele frequencies after selection are equal to those in their offspring. There is no further change in allele frequency from offspring to grand-offspring because we assume that no further selection is applied beyond this first generation. Therefore, the phenotypic response seen in the grand-offspring is a result of selection applied to their grandparents. The values for the phenotypic response to selection will be in relation to the strength of selection applied (i.e., in each case the value shown will be multiplied by the strength of selection, Embedded Image).