Fisherian runaway
（重定向自Runaway sexual selection）
![The peacock tail in flight, the classic example of a Fisherian runaway](/Images/godic/202502/08/Peacock_Flying4129.jpg")
![Ronald Fisher](/Images/godic/202502/08/R._A._Fischer4129.jpg")
![Female (left) and male (right) common pheasant, a sexually dimorphic species by which morphological traits vary between sexes](/Images/godic/202502/08/Male_and_female_pheasant4129.jpg")
![The peacock, on the right, is courting the peahen, on the left.](/Images/godic/202502/08/Peacock_courting_peahen4129.jpg")
Fisherian or Fisher's runaway, first proposed by Ronald Fisher in the early 20th century, is a hypothesized genetic sexual selection mechanism for the evolution of exaggerated male ornamentation (a subtype secondary sexual characteristic) observed in numerous species that produce offspring through sexual reproduction; based upon female choice, the preference or attraction of females for ornamented male mates.