Fisherian runaway or runaway selection is a sexual selection mechanism proposed by the mathematical biologist Ronald Fisher in the early 20th century, to account for the evolution of ostentatious male ornamentation by persistent, directional female choice. An example is the colourful and elaborate peacock plumage compared to the relatively subdued peahen plumage; the costly ornaments, notably the bird's extremely long tail, appear to be incompatible with natural selection. Fisherian runaway can be postulated to include sexually dimorphic phenotypic traits such as behavior expressed by a particular sex.
The peacock tail in flight, the classic example of an ornament assumed to be a Fisherian runaway
Female (left) and male (right) pheasant, a sexually dimorphic species
Peacock spider males perform courtship dances that display their boldly-patterned chelicerae, legs, and abdomens. Females are cryptic brown.
The peacock, on the right, is courting the peahen, on the left.
Sir Ronald Aylmer Fisher was a British polymath who was active as a mathematician, statistician, biologist, geneticist, and academic. For his work in statistics, he has been described as "a genius who almost single-handedly created the foundations for modern statistical science" and "the single most important figure in 20th century statistics". In genetics, his work used mathematics to combine Mendelian genetics and natural selection; this contributed to the revival of Darwinism in the early 20th-century revision of the theory of evolution known as the modern synthesis, being the one to most comprehensively combine the ideas of Gregor Mendel and Charles Darwin. For his contributions to biology, Richard Dawkins proclaimed Fisher as "the greatest of Darwin's successors". He is considered one of the founding fathers of Neo-Darwinism.
Fisher in 1913
As a child
Inverforth House, North End Way NW3, where Fisher lived from 1896 to 1904. He is commemorated with a blue plaque.
The peacock tail in flight, the classic example of a Fisherian runaway
