Male genital and wing morphology in the cactophilic sibling species Drosophila gouveai and Drosophila antonietae and their hybrids reared in different host plants.

Cactophilic Drosophila flies are excellent models to study adaptation to a relatively narrow spectrum of potential host plants and host-driven evolutionary diversification. Previous studies suggested a complex genetic architecture of wing and male genital morphology in phylogenetically basal species of the D. buzzatii cluster. In this work, we investigate the effect of experimental hybridization and host plant shifts on male genital and wing morphology in D. gouveai Tidon-Sklorz and Sene and D. antonietae Tidon-Sklorz and Sene, a pair of more recently derived species. We explicitly tested the hypotheses that wing and male genital morphology in interspecific hybrids depend on the host plant in which flies were grown. Our study shows that cactus hosts exert a strong effect on genital and wing morphology and that hybrids can be clearly differentiated on the basis of wing and genital morphology from both parental species. However, the extent of morphological differentiation between hybrids and pure species as well as plasticity patterns varied across organs, suggesting a complex genetic architecture for the studied traits.