Meeting Abstract
21.3 Jan. 5 Single- and multi-generational effects of atmospheric oxygen level on body size and tracheal dimensions in Drosophila melanogaster KLOK, C.J.*; KAISER, A.; LEE, W.H.; SOCHA, J.J.; HARRISON, J.F.; Arizona State University; Midwestern University; Argonne National Laboratory; Argonne National Laboratory; Arizona State University cjklok@asu.edu
Comparison of the historical records for maximal insect size and atmospheric oxygen level suggest that oxygen has influenced insect size through time. An increasing body of evidence using extant insects also suggests that atmospheric oxygen level affects many aspects of insect growth and development, especially size and tracheal investment. Many but not all insects tested show strong developmental plasticity of body size in response to atmospheric oxygen, with higher oxygen levels correlated with larger size and decreased tracheal dimensions or branching. Multi-generational exposure to variation in atmospheric oxygen level has the potential to amplify the effects of oxygen on size through natural selection. We tested this possibility by rearing Drosophila melanogaster at 10, 21, 40 and 60% oxygen for single and multiple generations, weighing the founding adults for every generation. Tracheal dimensions were determined using in vivo phase-contrast x-ray synchrotron image capturing and MATLAB M-file image analyses. Body sizes and leg tracheal dimensions did indeed respond to rearing oxygen. Normoxic flies maintained constant body sizes across multiple generations while 10% oxygen, size decreased by 7 to 10% and at higher oxygen levels male and female sizes increased by 10 and 15%, respectively. Leg tracheal diameters increased in hypoxia and decreased in hyperoxia, resulting in compensatory changes in tracheal oxygen diffusing capacity of 143% in 10% and 57% in 60% oxygen. Multi-general exposure increases the responses of insects to atmospheric oxygen level, supporting the hypothesis that oxygen has influenced insect size through the earth�s history. This research was funded by NSF grant IBN-0419704 awarded to JFH.
