The genome of Drosophila subpulchrella and the evolution of fresh fruit feeding in Drosophila suzukii: a comparative genomics approach

Drosophila suzukii is an invasive fruit fly pest that is spreading across temperate regions of North America and Europe. This species is characterized by a peculiar ecology, whereby females use a serrated ovipositor to lay eggs under the skin of fresh ripe fruits on which larvae feed. The genetic bases of such ecological and behavioral traits are starting to be investigated, for instance by combining genome-wide molecular evolution studies with ecological and behavioral observations. To increase the power of these analyses, we produced a draft genome and the transcriptome of D. subuplchrella, the closest known non-pest sister species of D. suzukii. Our comparative evolutionary analyses reveal a complex evolutionary history characterised by an initial speciation no older than 2 million years ago with past and possibly ongoing genetic admixtures between the two species. Moreover, the results indicate that two species share most of the chemosensory gene repertoire, indicating a progressive modification in the suzukii subgroup toward the peculiar D. suzukii feeding and oviposition behaviour. Finally, we could disentangle the evolutionary dynamics of Wolbachia symbionts in the two species. Our results indicate that comparative genomics between closely related species is particularly powerful when studying species-specific adaptations and ecological traits, which could be particularly relevant when defining management of invasive species.