Data from: Divergence of cuticular hydrocarbons in two sympatric grasshopper species and the evolution of fatty acid synthases and elongases across insects

Cuticular hydrocarbons (CHCs) play a major role in the evolution of
reproductive isolation between insect species. The CHC profiles of two
closely related sympatric grasshopper species, Chorthippus biguttulus and
C. mollis, differ mainly in the position of the first methyl group in
major methyl-branched CHCs. The position of methyl branches is determined
either by a fatty acid synthase (FAS) or by elongases. Both protein
families showed an expansion in insects. Interestingly, the FAS family
showed several lineage-specific expansions, especially in insect orders
with highly diverse methyl-branched CHC profiles. We found five putative
FASs and 12 putative elongases in the reference transcriptomes for both
species. A dN/dS test showed no evidence for positive selection acting on
FASs and elongases in these grasshoppers. However, one candidate FAS
showed species-specific transcriptional differences and may contribute to
the shift of the methyl-branch position between the species. In addition,
transcript levels of four elongases were expressed differentially between
the sexes. Our study indicates that complex methyl-branched CHC profiles
are linked to an expansion of FASs genes, but that species differences can
also mediated at the transcriptional level.