SEX-LINKED HERITABILITY OF A SEXUALLY SELECTED CHARACTER IN A NATURAL-POPULATION OF POECILIA-RETICULATA (PISCES, POECILIIDAE) (GUPPIES)

The relative extent of orange-pigmented spots in the colour patterns of male guppies, Poecilia reticulata, has previously been shown to be a basis for female choice. Parent-offspring and half-sib breeding experiments and selection experiments were conducted to determine if heritability of this character is maintained in the face of apparent sexual selection. The results demonstrate strong heritability of orange area. High father-son regression slopes, strong response to selection and a relatively small dam component of variance indicate that this character has Y-linked inheritance. This result for a quantitative character is in agreement with earlier work showing Y-linked inheritance of particular colour pattern elements in guppies. The high heritability of orange area suggests that this trait is probably not an indicator of fitness variation as postulated by some 'good genes' models for the evolution of female mate choice but that it does have the potential for further evolutionary change and elaboration.