S1-4.2 Jan. 5 From Vogelian Imagination to Gaseous Machinations: Animal Flight Performance in Variable-Density Air DUDLEY, Robert; Univ. of California, Berkeley firstname.lastname@example.org
Animal flight performance is typically studied at or near sea level within the contemporary atmosphere. Experimental alteration of the physical composition of gas mixtures, however, permits construction of novel flight media and the non-invasive manipulation of flight biomechanics and physiology. For example, replacement of atmospheric nitrogen with various noble gases yields a ten-fold variation in air density at a constant oxygen concentration. Normoxic reduction in air density elicits extraordinary biomechanical effort from flying animals; hummingbirds and euglossine orchid bees hovering in helium:oxygen gas mixtures demonstrate exceptionally high levels of power output. The physical effects of variable air density and oxygen availability across altitudinal gradients also strongly influence patterns of morphological and physiological adaptation in volant taxa. Furthermore, geophysical data suggest that both oxygen concentrations and total atmospheric pressure have changed dramatically during defining periods of metazoan evolution. In particular, global variation in atmospheric composition and density during the late Paleozoic may have influenced the initial evolution and subsequent diversification of pterygote insects, as well as the contemporaneous and taxonomically widespread phenomenon of arthropod gigantism.