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Conférence d'Anthony W. F. Edwards
Anthony W. F. Edwards (Université de Cambridge) nous fera l'honneur de faire une conférence sur THE FUNDAMENTAL THEOREM OF NATURAL SELECTION.WHAT IT IS AND WHAT IT IS NOT.
R.A.Fisher’s Fundamental Theorem of Natural Selection is the centre-piece of his 1930 book The Genetical Theory of Natural Selection. A modern wording is:
The rate of change in the mean fitness of a population ascribable to natural selection acting through changes in gene frequency is equal to its genic variance in fitness.
For many years the name of the Theorem was misappropriated to apply to the change in the mean fitness without the qualification and it was criticized as false or at best an approximation. When it began to be understood as applying only to that part of the change in mean fitness caused by gene-frequency change the explanation was couched in discrete time, which created further problems of interpretation. Here we point out that Fisher’s treatment is actually in continuous time, is exact, and we give his proof.
Even under its correct interpretation the Theorem has been held to have an optimization interpretation, but Fisher was opposed to this on the grounds that in nature the environment of a gene (which in his view includes the rest of the genome) is in a state of flux. It is a descriptive theorem and not a dynamic one. Attempts to capture the essence of natural selection by maximisation arguments, whether in Sewall Wright’s original form, or by more recent variants involving entropy or information (either Shannon’s or Fisher’s), do not correspond to Fisher’s thinking.
Sa conférence sera suivie d'un commentaire par Jean Gayon, Professeur à l'Université Panthéon-Sorbonne et directeur de l'IHPST puis d'une discussion avec le public.