Insects use sex pheromones as a reproductive isolating mechanism to attract conspecifics
and repel heterospecifics. Despite the profound knowledge of sex pheromones, little is known
about the coevolutionary mechanisms and constraints on their production and detection.
Using whole-genome sequences to infer the kinship among 99 drosophilids, we investigate
how phylogenetic and chemical traits have interacted at a wide evolutionary timescale.
Through a series of chemical syntheses and electrophysiological recordings, we identify 52
sex-specific compounds, many of which are detected via olfaction. Behavioral analyses reveal
that many of the 43 male-specific compounds are transferred to the female during copulation
and mediate female receptivity and/or male courtship inhibition. Measurement of phylogenetic
signals demonstrates that sex pheromones and their cognate olfactory channels evolve
rapidly and independently over evolutionary time to guarantee efficient intra- and interspecific
communication systems. Our results show how sexual isolation barriers between
species can be reinforced by species-specific olfactory signals.