Aerodynamics, Wing Biomechanics, and the Evolutionary Diversification of the Chiroptera

在这项研究中，PI将研究蝙蝠不同翅膀形式的功能意义和飞行进化。之所以选择蝙蝠作为研究对象，是因为蝙蝠有近1000种，体重从2克到2000克不等，拥有多种翅膀形状和飞行模式，并且具有非常适合建模的解剖组织（由弹性翼膜连接的刚性骨骼元素）。该项目将提出以下问题：1)蝙蝠的形态和翅膀运动学如何影响关节力和力矩以及翅膀内形成的皮肤和骨骼应力？2)蝙蝠的形态和翅膀运动学如何影响翅膀的机动性、结构稳定性和气动性能，以及飞行的机械动力；3)在这些力量的支配和这些结果的约束下，蝙蝠的飞行是如何从非飞行的哺乳动物进化而来的？这些问题将通过完成一系列相互关联的目标来回答。基于灰头飞狐的飞行蝙蝠的机械和生物逼真的计算机模型已经开发出来。然后，这个计算机模型被用来生成有关机翼关节处受力、翼骨和翼皮受力、飞行的机械动力、翼骨抗屈曲的能力以及机翼的稳定性和可操作性的信息。该模型将扩展到代表不同血统、体型和飞行方式的一组物种。这将通过捕获高速视频序列和从这些动物在大型风洞中飞行的详细翼膜应变测量来获得有关几个物种的翅膀运动和结构的详细信息来完成。我们会特别注意分析体型、飞行模式、翅膀形状、飞行速度和生物力学特性对模型输出的影响。模型结果将被映射到现存蝙蝠及其近亲的一个有充分支持的系统发育上，以研究翼目动物飞行性能的进化。然后，该模型将扩展到蝙蝠祖先提出的理论形态学，结果将用于检验关于最早蝙蝠的性质和蝙蝠飞行起源的假设的相对优点。最后，这种分析结果的复杂性需要新的数据可视化方法。将开发动态三维图形动画，以一种将大大增加科学家和公众理解的方式来呈现结果。这个三维可视化程序也将在PIs网站上实施。支持性文件将用于创建一个网站，以促进高中或普通公众对空气动力学、动物飞行和蝙蝠进化的理解。这个网站将由一个由本科生、研究生和更资深的工作人员组成的跨学科团队部分建立，并将利用生物学、工程学和计算机科学。

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.