Recent Topics Posters
Mertz, Meredith L. , Schwendemann, Andrew B. , Wang, George , Thatcher, Scott L. , Osborn, Jeffrey M. .
Computational Modeling of Flight Characteristics for Extant and Fossil Saccate Pollen Grains.
THE present study continues investigation into the adaptive significance of saccate pollen through correlation of structural and aerodynamic features. Sacci, or air-filled bladders, are common features of pollen grains of many anemophilous gymnosperms. Recent studies indicate that sacci of some extant conifer pollen function hydrodynamically upon arrival at the pollination drop. Sacci have also been thought to add significant surface area, yet minimal mass, to grains, thereby increasing dispersal distance during wind pollination. However, no published studies have tested this hypothesis. The goal of this study is to develop a mathematical model for pollen settling speeds, and refine the techniques used to verify that model. A computational model based on structural characters of pollen grains has been developed using electron microscopy, mathematical modeling, and the saccate pollen of three extant conifers (Pinus, Falcatifolium, Dacrydium). The model calculates terminal settling velocities based on structural characters of the pollen grains, including: lengths, widths, and depths of the main body and sacci; angle of saccus rotation; saccus wall thicknesses, endoreticulations, intine, and exine; and surface ornamentation. The resolution of the model has been strengthened using more accurate drag coefficients based on the geometry of each pollen grain, and error propagation methods have helped define the limits of the model. Improved stroboscopic photography techniques, using digital photography and image analysis, have aided in the validation of the model. Moreover, bi-saccate pollen grains caught on scanning electron microscopy stubs during stroboscopic photography have verified the modelís assumptions about grain flight orientation and have enhanced interpretation of the stroboscopic images. The mathematical model, based on structural characters, permits flight properties to be measured without physically testing pollen, allowing the flight dynamics of fossil pollen to be investigated. Several fossils have been studied, including non-saccate (Monoletes), mono-saccate (Gothania), and bi-saccate (Pteruchus, Caytonanthus, Pinus) pollen types.
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1 - Truman State University, Biology Department, Division Of Science, 100 E Normal Street, Kirksville, Missouri, 63501-4221, USA
2 - Truman State University, Division of Mathematics and Computer Science, 100 E. Normal Street, Kirksville, Missouri, 63501-4221, USA
Presentation Type: Recent Topics Poster
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM