An interpretation and proof of the Fundamental Theorem of Natural Selection

Theor Popul Biol. 1989 Oct;36(2):167-80. doi: 10.1016/0040-5809(89)90028-2.


Fisher's "Fundamental Theorem of Natural Selection" has long caused controversy in population genetics theory. Viewed as a statement about the increase, or rate of increase, of mean fitness over time, it encounters difficulties with cases arising in a multi-locus system for which mean fitness can decrease. An interpretation of the theorem is put forward here which implies that it is correct as a mathematical statement, but of less biological value than was claimed by Fisher.

MeSH terms

  • Gene Frequency
  • Genotype
  • Humans
  • Models, Genetic
  • Models, Statistical
  • Selection, Genetic*
  • Sexual Behavior