Intra-sexual selection in Drosophila

Epigamic selection includes the major part of what Darwin meant by sexual selection, and is introduced to apply to characters which increased the fertility of a given mating and therefore had a selective value for the species as a whole.

Abstract

SINCE Darwin first wrote on the subject in 1871, sexual selection has been generally accepted as one of the basic facts of biology.The evidence in its favour seems, however, to be mainly circumstantial.Its existence has usually been inferred from sex differences depending on what are called secondary sexual characters which are supposed to have arisen as results of that selection.Such an approach has its dangers, and Huxley (1938) has made important criticisms of the original concept of sexual selection.He has shown that a large number of characters which have been attributed to sexual selection are unconnected with competition for mates.This is particularly the case in monogamous birds which offer some of the most striking examples of secondary sexual differences.In the first place monogamy,