Quantifying evolution by natural selection

The theme of this paper is that Fisher's "Fundamental Theorem of Natural Selection" has various deficiencies as a quantification of the effect of natural selection in a Mendelian population which are not shared by a new different theorem described in this paper. The deficiencies in Fisher's theorem are listed in this paper. The new theorem focuses on the implications of changes in gene frequencies under natural selection and not, as does the Fundamental Theorem of Natural Selection, on changes in mean population fitness. Whereas the algebra in the new theorem corresponds in places to that in the Fundamental Theorem of Natural Selection, the approach, perspective and conclusion of the new theorem are different from those of the Fundamental Theorem of Natural Selection.