Mate choice

Mate choice or intersexual selection is an evolutionary process in which selection, normally of a male mate by a female chooser, is dependent on the attractiveness of his phenotypic traits. It is one of two components of sexual selection (the other being intrasexual selection). Charles Darwin first introduced his ideas on sexual selection in 1871 but they were initially rejected. Ronald Fisher then developed the idea in his 1915 paper The evolution of sexual preference outlined the Fisherian runaway theory in 1930. Advances in genetic and molecular biology techniques have accompanied major progress in this field recently.

Five currently recognized mechanisms, which can co-occur, and for each of which there are many examples, explain the evolution of mate choice.

In systems where mate choice exists, one sex is competitive with same-sex members and the other sex is choosy (selective when it comes to picking individuals to mate with). In most species, females are the choosy sex that discriminate amongst competitive males but there are several examples of reversed roles (see below).