Meeting Abstract

79.6  Monday, Jan. 6 11:15  Oxygen Modulates Density Effects on Body Size in Drosophila melanogaster BIDDULPH, T.A.*; HARRISON, J.F.; Arizona State University; Arizona State University tbiddulp@asu.edu

Larval crowding has been shown to reduce body size in Drosophila melanogaster but the mechanisms responsible for this effect remain unclear. While nutritional limitation and larval competition are two factors that likely play an important role in the determination of body size, it may be possible that hypoxia occurs in the media at high densities and this might be a factor in the density effect on body size. To partially test this hypothesis, Drosophila melanogaster were reared in 10, 21, or 30 kPa oxygen at three densities from egg to adult. Adults were collected during the first two days after eclosion began in each treatment and were starved for one day with agar gel to prevent desiccation before their masses were recorded. There was a significant interaction between oxygen and density on adult body mass (two-factor ANOVA, N=146, p > 0.0000001). At low densities, as seen in prior studies, hypoxia suppressed body size while hyperoxia had no effect, but at high densities hyperoxia increased body size and hypoxia had no effect. These results demonstrate that oxygen needs to be considered as a potential major factor in causing the reduction of body size in Drosophila melanogaster at high densities, and suggest that larval crowding causes hypoxia in the media. This study was funded by the SOLUR Program at ASU as well as NSF IOS 1122157 and NSF 0938047.