Testosterone-induced male traits in female puffs (Philomachus pugnax): autosomal inheritance and gender differentiation

A balanced polymorphism in male mating behaviour exists in male ruffs. with no obvious parallel expression in females. Pedigree data of male phenotype s support an autosomal model of inheritance, in contrast to sex-linked inhe ritance patterns found in other taxa with sex-limited alternative mating st rategy polymorphisms. We tested this model by inducing male courtship behav iour in gonad-intact female ruffs, using subcutaneous testosterone implants that produced physiological concentrations of testosterone. The implants r apidly induced in females both types of male mating behaviour, an increase in body mass typical of pre-breeding males, and the growth of normally male -limited breeding plumage. As predicted under an autosomal model, the distr ibutions of induced male behaviour types in females paralleled those of the ir brothers and half-brothers, and were inconsistent with sex-linked models . Effects were reversible, and experimental females bred normally in subseq uent years. Our results show that genotype-specific male characteristics ca n be induced by testosterone in female adults that have presumably not unde rgone neural organization for them early in life, showing direct use of gen etic information in intra- and intersexual differentiation.