HERITABLE VARIATION IN A PLUMAGE INDICATOR OF VIABILITY IN MALE GREAT TITS PARUS-MAJOR

THE idea that female birds choose mates on the basis of genetic quality is a contentious issue in sexual selection1,2 because empirical evidence is lacking3,4. Females mating with attractive males may obtain direct benefits such as high quality parental4-6 or breeding resources7, or indirect benefits such as offspring of high genotypic quality8-11. This debate could be resolved if the traits associated with attractiveness in males have a high heritability, and correlate with the viability of their offspring. Here I report the results of a cross-fostering experiment in great tits in which parents raised unrelated young. This showed that the plumage trait associated with attractiveness in males was heritable, and that the viability of male offspring was correlated with the plumage traits of their putative father. These results show that females mating with attractive male great tits realize an indirect fitness advantage.