A new Amazonian species from the Drosophila annulimana species group (Diptera, Drosophilidae) / Uma nova espécie amazônica pertencente ao grupo de espécies Drosophila annulimana (Diptera, Drosophilidae)

Drosophila caxiuana sp. nov., Drosophila subgenus, is described and illustrated. This new species was collected in the Amazonian Biome (Caquajó river, Portel, Pará, Brazil) and is an atypical species to the group due the unusual morphology of the male terminalia.

Drosophila caxiuana sp. nov., subgênero Drosophila, é descrita e ilustrada. Essa nova espécie foi coletada no Bioma Amazônico (Rio Caquajó, Portel, Pará, Brasil) e é uma espécie atípica deste grupo devido à morfologia incomum da terminália masculina.

The reaction norm for abdominal pigmentation and its curve in Drosophila mediopunctata depend on the mean phenotypic value.

The idea of a general independence between the phenotypic plasticity and the mean value of a trait is, presently, a consensus. Here, we use the reaction norm of abdominal pigmentation (number of dark spots) of Drosophila mediopunctata in response to temperature, to test this idea. We raised eight strains, bearing two different chromosomal inversions and with varying mean phenotypic values, under 11 temperatures in a thermal gradient to test for predictions concerning mean phenotypic values, chromosomal inversions, and reaction norms. Our results revealed a strong effect of different phenotypic groups and no effect of different karyotypes on reaction norms. Moreover, we found a significant negative correlation between mean phenotypic value and the curvature of the reaction norms, revealing a high dependency of the reaction norm shape on mean phenotypic value. These results clearly reject the idea of genetic independence between mean value and phenotypic plasticity, and may indicate a pattern of correlation, which may include results from other traits and species, with an importance that has not been fully appreciated.