Data from: A nonrandom subset of olfactory genes is associated with host preference in the fruit fly Drosophila orena

Specialization onto different host plants has been hypothesized to be a
major driver of diversification in insects, and traits controlling
olfaction have been shown to play a fundamental role in host preferences.
A diverse set of olfactory genes control olfactory traits in insects, and
it remains unclear whether specialization onto different hosts is likely
to involve a nonrandom subset of these genes. Here, we test the role of
olfactory genes in a novel case of specialization in Drosophila orena. We
report the first population-level sample of D. orena on the West African
island of Bioko, since its initial collection in Cameroon in 1975, and use
field experiments and behavioral assays to show that D. orena has evolved
a strong preference for waterberry (Syzygium staudtii). We then show that
a nonrandom subset of genes controlling olfaction-–those controlling
odorant-binding and chemosensory proteins–-have an enriched signature of
positive selection relative to the rest of the D. orena genome. By
comparing signatures of positive selection on olfactory genes between D.
orena and its sister species, D. erecta we show that odorant-binding and
chemosensory have evidence of positive selection in both species; however,
overlap in the specific genes with evidence of selection in these two
classes is not greater than expected by chance. Finally, we use
quantitative complementation tests to confirm a role for seven olfactory
loci in D. orena’s preference for waterberry fruit. Together, our results
suggest that D. orena and D. erecta have specialized onto different host
plants through convergent evolution at the level of olfactory gene family,
but not at specific olfactory genes.