This theory accounts for the maintenance of a polymorphism (i.e., two or more alleles for the same trait) by means of stabilising selection. Natural selection does not create genetic variation, but instead removes it (by directional selection) or preserves it (by stabilising selection). In the first case, the outcome is a transient polymorphism and in the second a balanced polymorphism. Examples of balanced polymorphisms include birthweight and adult height, and in such cases heterozygotes have greater fitness than homozygotes. However, most polymorphisms are adaptively neutral and confer no selective advantage on either transient or balanced polymorphisms. <\/p>\n
See Polymorphism<\/a>, Theory of natural selection<\/a><\/p>\n <\/body><\/html><\/p>\n","protected":false},"excerpt":{"rendered":" This theory accounts for the maintenance of a polymorphism (i.e., two or more alleles for the same trait) by means of stabilising selection. Natural selection does not create genetic variation, but instead removes it (by directional selection) or preserves it (by stabilising selection). In the first case, the outcome is a transient polymorphism and in … <\/p>\n