Two pathways for courtship behavior

The male-specific product of the fruitless gene (fru^M) in Drosophila melanogaster is necessary for all aspects of male courtship. However, previous studies have reported observations of courtship-like behaviors in males lacking fru^M when these flies are housed with other males for several days. Now, Yufeng Pan and Bruce Baker report that this experience-dependent development of courtship behaviors requires the expression of male-specific doublesex (dsx^M) in neurons that normally express both genes (Cell 156, 236–248, 2014). Males lacking fru^M that were housed for at least 1 day with other males, conspecific females or females of a different species all showed courtship behaviors toward males and females in a courtship assay. Wild-type males, however, rarely court other males, and their courtship of females is not dependent on previous social experience. The authors further demonstrated that, when dsx^M was replaced by the female-specific dsx in neurons that normally express both dsx^M and fru^M, all courtship behavior was lost. Finally, they demonstrated that genetic females expressing dsx^M also courted females. These data identify Drosophila male courtship as a genetic model for understanding the interplay between innate and acquired behavior.