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.