Meeting Abstract

P1.97  Friday, Jan. 4  Effects of Wind Speed on Floral Motion Characteristics LANDRIGAN, J*; SPRAYBERRY, JDH; Muhlenberg College; Muhlenberg College jl242050@muhlenberg.edu

Plant-pollinator relationships are classical systems for examining coevolution. In hovering pollinators, the biomechanical structure of flowers may impact fitness. Previous work has found that Manduca sexta not only feed-from and track horizontally-moving flowers better than looming flowers, they actively prefer to feed from horizontally-moving flowers. This naïve preference implies a potential selective force on hawkmoth-pollinated flowers. A preliminary motion analysis showed that these flowers exhibit more motion in the horizontal rather than the looming axis. A more thorough investigation of this system requires a deeper understanding of floral motions. The characteristics of floral motion (frequency, amplitude and direction) are influenced by morphological features (stem structure, physical organization of inflorescences, inflorescence shape, etc.). Although engineering theory predicts that frequency of floral motions will be dominated by stem properties (such as length and stiffness) rather than wind speed, the effects of floral structure may be more complex. This project examined the effect of wind speed on floral motions by filming flowers in a wind tunnel at 1, 5, & 10 m/s. Flower videos were digitized and resultant position traces were filtered, perspective corrected, then subjected to an FFT to produce their amplitude spectra. Results were variable across species, but indicated that frequency of flower motion is not necessarily constant across wind speeds. This variability implies that floral morphology (beyond stem length and stiffness) impacts floral motion characteristics. These data will allow for a better understanding and analysis of companion data on natural floral motions, as environmental wind conditions are difficult to characterize.