Data from: Rapid divergence of wing volatile profiles between subspecies of the butterfly Pieris rapae (Lepidoptera: Pieridae)

Complex signaling traits such as pheromone profiles can play an important
role in the early stages of reproductive isolation between populations.
These signals can diverge along multiple trait axes, and signal receivers
are often sensitive to subtle differences in signal properties. In the
Lepidoptera, prior research has highlighted that natural selection can
drive rapid chemical signal divergence, for instance via mate recognition
to maintain species boundaries. Much less is known about the occurrence of
such changes for predominantly sexually-selected chemical signals, such as
those released by many male lepidopterans. We evaluated the divergence in
male and female wing volatile profiles between two recently-isolated
subspecies of the pierid butterfly Pieris rapae: Pieris rapae rapae and
Pieris rapae crucivora. In laboratory settings, these subspecies exhibit
strong pre-mating isolation, with females rejecting males of the opposite
subspecies despite the fact that males direct equivalent courtship effort
toward females of either subspecies. Using gas chromatography-mass
spectrometry, we analyzed the volatile chemical profiles of individual
males and females of each subspecies. We find that males of each
subspecies differ in their wing volatile profiles, including quantitative
differences in a male sex pheromone, ferrulactone. In contrast, female
wing volatiles profiles have diverged significantly less. These
sex-specific patterns suggest that male chemical profiles may play a role
in the observed pre-mating isolation between these two subspecies,
providing support for future investigations of sexually-selected chemical
traits in population divergence.