Fisher's fundamental theorem of natural selection

The Fundamental theorem of natural selection formulated mathematical laws of population genetics for the increase in fitness of organisms

History

The theorem was first formulated by Ronald Fisher in his book The Genetical Theory of Natural Selection in 1930.

" The rate of increase in fitness of any organism at any time is equal to the genetic variance of his fitness at this time. "

Or, in a more modern terminology:

"The rate of increase in the mean fitness of any organism at any time ascribable to natural selection acting through changes in gene frequencies is exactly equal to its genetic variance in fitness at time did. "

" The increase in the average fitness of each organism that follows at any time from the natural selection and is mediated by a change in gene frequency is exactly equal to the genetic variance in fitness at that time. "

Fisher stated that it was " not a little instructive, making it similar to a law should hold the supreme position among the biological sciences." Nevertheless, it was forty years read misunderstood and, as it would say that the average fitness of a population would always increase, although models showed that this is not the case. The misunderstandings can be widely seen as a result of Fischer's feud with the American geneticist Sewall Wright, this was done mainly on the subject of fitness landscapes.

The American George R. Price in 1972 showed the accuracy of Fisher's theorem and the proof as well, except for one or two typos, is correct. (see Fischer's equation). Price showed that the results were correct, but this did not of great significance. The sophistication, drew attention to the Price and made ​​understanding difficult is that the theorem is a formula for a portion of the changes in gene frequency, but not for all of them. This is a part that would be due to natural selection.

Recent work (examined in Counts 2003) build on Prices understanding in two ways. A aims to improve the theorem by it completes, for example, by finding a formula for the total of the change in the gene frequency. The other argues that the partial change in fact has a great conceptual significance and aims to extend similar results to the partial change in ever more general population genetic models.

Because of the irritating factors tests of the fundamental theorem are rare. For an example of this effect in a natural population, see Bolnick, 2007.