In this study, the PI will investigate the functional significance of different wing forms and the evolution of flight in bats. Bats have been selected as the study organisms because they comprise close to 1000 species, and range in body mass from 2 to close to 2000 g, possess a diversity of wing shapes and flight modes, and are characterized by an anatomical organization (rigid bony elements interconnected by an elastic wing membrane) that is ideally suited to modeling. This project will ask: 1) how do the morphology and wing kinematics of bats affect the joint forces and moments and the skin and bone stresses developed within the wing?; 2) how do the morphology and wing kinematics of bats affect the maneuverability, structural stability and aerodynamic performance of the wing, and the mechanical power of flight?; and 3) how has bat flight, dictated by these forces and constrained by these results, evolved from non-volant mammals? These questions will be answered by accomplishing a series of interrelated objectives. A mechanically and biologically realistic computer model of a flying bat, based on the grey-headed flying fox, has been developed. This computer model is then used to generate information about the forces developed at the wing joints, the stresses in the wing bones and skin, the mechanical power of flight, the ability of the bones to withstand buckling, and the stability and maneuverability of the wing. The model will be extended to a group of species representing diverse lineages, body sizes and flight modes. This will be accomplished by obtaining detailed information about the wing motions and structure of several species by capturing high speed video sequences and detailed wing membrane strain measurements from these animals flying in a large wind tunnel. Special attention will be paid to the analysis of the effect of body size, flight mode, wing shape, flight speed, and biomechanical properties on the model outputs. Model results will be mapped onto a well-supported phylogeny of extant bats and their closest relatives to examine the evolution of flight performance within the Chiroptera. The model will then be extended to theoretical morphologies proposed for bat ancestors, and results will be used to examine the relative merits of hypotheses about the nature of the earliest bats and the origins of bat flight. Finally, the complexity of the results of this analysis require novel approaches to data visualization. Dynamic three-dimensional graphical animations will be developed to present results in a manner that will greatly increase understanding by both scientists and the general public. This 3-D visualization program will be also be implemented on the PIs web site. Supporting documentation will be used to create a web site to facilitate high school or general public level understanding of aerodynamics, animal flight, and bat evolution. This web site will be built in part by an interdisciplinary team of undergraduates, graduates, and more senior staff, and will draw on biology, engineering, and computer science.
