Meeting Abstract
P3.98 Sunday, Jan. 6 Comparative anatomy of flight and contour feathers in aquatic birds JOHNSON, K.E.*; ANDRUS, C.J.; MIDDLETON, K.M.; California State University San Bernardino; Western University of Health Sciences; University of Missouri katiejay1987@gmail.com
The evolutionary transition from aerial to aquatic flight in penguins and alcids involved long-appreciated and well-studied changes in anatomy and physiology, and prior studies have addressed locomotor kinematics and muscle physiology in these clades. For underwater flight, the wing, including feathers, must be stiff enough to resist a fluid reaction force sufficiently large for propulsion in a dense and viscous fluid. Recent discoveries of basal penguins with anatomically “modern” feather morphology have highlighted the need for a better understanding of feather biomechanics and evolution. To explore the role of the physical environment in shaping the mechanical design of feathers, we compared cross-sectional anatomy of flight and contour feathers in fourteen species of seabirds, including aerial fliers, foot-propelled divers, wing-propelled divers, and flightless wing-propelled divers. Serial histological sections of the feather rachis were measured to determine cross-sectional areas and indices of flattening and resistance to bending and torsion. Two measurements, including aspect ratio (a measure of dorsoventral flattening) and standardized resistance to torsion, reveal that penguin contour feathers are significantly flatter and more resistant to torsion than closely related or ecologically similar birds, even after accounting for phylogenetic relationships. Despite differences in ecology, flight feathers showed similar scaling patterns across species, when corrected for rachis position. Short feathers are geometrically and biomechanically similar to the same lengths of the distal ends of large feathers. These results suggest a general mechanism for feather construction in which feather length is the main determinant of geometry. (NSF DEB 0949945)
