Wing plastic response to temperature variation in two distantly related Neotropical Drosophila species (Diptera, Drosophilidae)

Phenotypic plasticity has been described for morphological and life-history traits in many organisms. In Drosophila, temperature drives phenotypic change in several traits, but few Neotropical species have been studied and whether the phenotypic variation associated with plasticity is adaptive remains unclear. Here, we studied the phenotypic response to temperature variation in the distantly related Neotropical species Drosophila mercatorum Patterson and Wheeler, 1942 and Drosophila willistoni Sturtevant, 1916. We evaluate if wing shape variation follows that observed in the Neotropical species Drosophila cardini Sturtevant, 1916: round wings at lower temperatures and narrower wings at higher temperatures. The variation in egg–adult development time and in wing size, shape, and allometry was described using reaction norms and geometric morphometrics. In both species, development time and wing size decreased with increasing temperature and wing allometry showed that size explained ≈10% of the shape variation. Wing shape, however, exhibited contrasting responses. At higher temperatures, D. mercatorum developed slightly slender wings, following the pattern previously found for D. cardini, whereas D. willistoni developed plumper and shorter wings, supporting previous studies on Drosophila melanogaster Meigen, 1830. We conclude that all traits studied here were influenced by temperature, and that wing shape seems also to be influenced by phylogeny.