Meeting Abstract
Variation in atmospheric oxygen over geologic time has been hypothesized to affect the evolution and physiology of insects. However, the insect fossil record is composed of mostly isolated wings, which presents challenges in interpreting the data. Therefore, understanding how wing morphology varies with atmospheric oxygen is a critical step in addressing these hypotheses. Wing veins contain tracheae that deliver oxygen to the wing and may control the patterning and morphology of the veins during development. It has previously been shown that rearing oxygen is inversely correlated with tracheal widths in the legs and bodies of insects, but wing veins remain unexplored. Therefore, we hypothesized that wing vein diameters should be inversely correlated with rearing oxygen. To this end, Drosophila melanogaster were reared from egg to adult under three different oxygen concentrations: 12%, 21%, and 31%. The wings were then dissected and imaged using a mechanical stage mounted on an inverted microscope at 40x magnification. Wing area, wing vein diameters, and wing vein lengths were all measured using ImageJ. Wing area and wing vein diameter both were inversely correlated with rearing oxygen. In a second experiment, flies were again reared in three different oxygen concentrations and then flown in all three oxygen levels to test the effect of these changes in wing morphology on flight performance. Flies performed best in the oxygen level they were reared under indicating changes in wing morphology are adaptive in response to oxygen variation. These results point to the ability to use wing morphology in the fossil record to interpret evolutionary changes. Additionally, this suggests that wing vein diameters could potentially act as a proxy for atmospheric oxygen over geologic time.
