Manipulating a seemingly non-preferred male ornament reveals a role in female choice

Abstract

Past studies of a feral South African population of guppies have shown that females use the area of orange coloration borne by males as a criterion for mate choice. However, males bear spots of other colours, the most noticeable of which is black. We investigate whether female preference can maintain the black spots of male guppies despite the apparent unimportance of black to female choice in correlative studies. When part of a male's black pigmentation is removed, his `attractiveness' to females decreases. This supports the hypothesis that in male animals with several ornaments, seemingly non-preferred ornaments can be maintained by female choice. These findings are discussed in the context of several models which account for the evolution of multiple male ornaments.