98.6 Saturday, Jan. 7 Wing Reduction and Flight Biomechanic in Stick Insects (Insecta: Phasmatodea) ZENG, Yu*; DUDLEY, Robert; Univ. of California, Berkeley; Univ. of California, Berkeley email@example.com
Many unresolved questions in insect flight evolution relate to the transition between flightless and flying insects. Functional analysis of transitional forms using anatomical intermediates may help to explain how complex morphology and biomechanical features evolved. The stick insects exhibit a wide spectrum of wing size variation, and our recent study revealed diverse flight performances associated with these wings. The venation and membrane morphology were quantitatively studied in wings of different sizes, and the results showed a continuous structural reduction and simplification along the size gradient. Assisted with high-speed filming and motion analysis, we examined the biomechanics of flight performed with different wings, from full flapping capacity to parachuting with winglets. In wings of reduced sizes, we found rudimentary wing kinematics, specialized behavior and distinctive aerodynamic features different from typical flapping wings. Comparison among different flight modes suggested a transitional pattern in the aerodynamic functions coupled with relative wing size. Our results demonstrated a connection between intermediate wing morphology and various forms of gliding flight in an arboreal context. The adaptive significance of these wing designs may help to understand the evolutionary transitions between flightless and volant forms.