Meeting Abstract

P3.49  Jan. 6  Intra- and interspecific variation in flight morphology and kinematics of alpine bumblebees DILLON, M. E.*; DANIEL, T. L.; HUEY, R. B.; University of Washington, Seattle; University of Washington, Seattle; University of Washington, Seattle dillonm@u.washington.edu

Alpine conditions pose distinct challenges to flying animals because cold air, lower oxygen availability, and reduced air density can substantially impair the physiology and biomechanics of flight. Nonetheless, bumblebees (genus Bombus) thrive on mountains and are typically important pollinators of distinctive alpine floras. The decline in air density at higher elevations imposes an aerodynamic limit to flight because aerodynamic forces produced by wing flapping are directly proportional to air density. Bumblebees could compensate for the altitudinal decline in air density through changes in morphology and wingbeat kinematics. Specifically, longer wings, and greater wing area relative to body size would both help to counteract the increase in induced power associated with reduced air density at high altitude. Similarly, bumblebees could increase wing beat frequency or stroke amplitude to fly at high altitudes. To test these hypotheses, we measured morphology and flight kinematics of bumblebees collected across a large altitudinal gradient in central California (Yosemite N.P.). Intraspecific comparisons suggested that bumblebees have longer wings relative to body size, lower wing loading, and increased stroke amplitude at high altitudes. Interspecific comparisons (not corrected for phylogenetic relatedness) also provide support for these trends. A recent molecular phylogeny will allow us to repeat the analysis using phylogenetic independent contrasts.