Conservation and diversification of mating behavior patterns among three sibling species in the Drosophila subobscura species subgroup

Behavioral traits are known to evolve rapidly, often even preceding morphological or physiological changes. However, the genomic and neural bases for such rapid behavioral changes remain to be clarified. Drosophila subobscura is a rare example of a species that performs nuptial gift giving, while the mating behaviors of the other two members of the subobscura species subgroup, D. madeirensis and D. guanche, remain largely unstudied. In the present study, we characterize and compare mating behaviors of three sibling species of the subobscura species subgroup, with the aim of providing a starting point for investigating the neural mechanisms underlying reproductive behavioral divergence in the subobscura subgroup. We find that D. madeirensis males exhibit a rich repertoire of courtship behaviors—very similar to that of D. suboscura—including tapping, midleg swinging, proboscis extension and nuptial gift giving. In contrast, D. guanche males perform only tapping and lack the other premating displays, yet they still copulate successfully. We postulate that female promiscuity has promoted the loss of multiple components of the male courtship repertoire in D. guanche. The relatively recent divergence among these species (∼1.72 Myr between D. guanche and other two species) suggests that only a few genomic and neural changes underpin the striking differences in mating behavior within the subobscura species subgroup. This system offers a promising platform for uncovering the mechanistic basis of rapid behavioral evolution.