CAREER: Establishing Links between Musculoskeletal Morphology and the Biomechanics of Bipedal Hopping in Desert Environments

在它们的环境中运动是大多数动物的基本特征(例如，跑步、游泳、飞行)，动物如何执行这一任务的机制直接影响进化的成功，因为运动涉及到有效的防御、寻找配偶和觅食。几个世纪以来，生物力学研究为开发和测试假说提供了基础，假说范围从陆地运动的一般控制原则到四肢和肌肉的形式和功能之间的特定关系。然而，这些研究中的绝大多数是在实验室的跑步机和跑道上进行的，这些跑步机和跑道与动物实际生活的环境几乎没有相似之处。为了真正了解动物的肌肉和骨骼解剖与运动能力之间的关系，有必要了解在动物的自然环境中执行的任务的机械需求。理解自然栖息地中的这些关系仍然是一个重要的挑战。因此，这项研究的目的是通过一系列实验来检验解剖学和运动表现之间的关系，目的是详细了解不同肌肉是如何参与运动任务的。实验将揭示肌肉和骨骼的特定特征如何影响特定肌肉在机械挑战的自然环境中移动时的功能。这项研究的结果将促进对单个肌肉的功能作用的了解，这在比较生物力学研究中是罕见的，并为更好地理解机械能如何通过复杂的肌肉骨骼系统传递奠定了基础。应用这一知识可以改进自主机器人、下肢假肢和其他人类运动增强装置的设计。本研究的目的是以沙漠袋鼠为动物模型，阐明沙漠环境中肌肉骨骼形态与两足跳跃动力学的关系。人们普遍认为，两足跳跃之所以进化，是因为它提供了与夸张的后肢形态相关的运动性能优势(例如，更快的最高速度、更高的耐力、加速能力)；然而，并不是所有的跳跃物种都具有特定的优势。为了实现拟议的目标，这项研究将包括野外栖息地使用的分析、实验室步态动力学、活体肌肉动力学以及详细的计算机建模和模拟。这将是第一次将所有这些方法结合在一起的研究，以全面了解肌肉骨骼形态和性能之间的关系。这一强大的综合方法将被用于实现两个具体的研究目标：1)量化沙漠毛虫在其自然环境中在基质和地形上跳跃的机械需求；2)阐明肌肉骨骼形态与栖息地利用之间的关系。拟议的研究结果将以一种以前不可能的方式，在自然条件下的运动能力与肌肉骨骼形态和肌肉功能之间建立直接联系。对动物如何以及为什么跳跃的理解将推动进化生物学、比较解剖学和生物力学领域的发展，并导致自主机器人、下肢假肢和其他运动增强设备的设计改进。这项建议支持一项教育计划，以开发一门实地课程，为学生提供机会，通过研究驱动的、基于现场的栖息地利用、功能形态和行为分析，整合他们所学到的生态学和进化知识。本课程多年的行为和栖息地使用数据将为解释形态和生物力学结果提供更广泛的背景。

Movement through their environments is a fundamental characteristic of most animals, (e.g., running, swimming, flying) and the mechanics of how animals perform this task have direct implications for evolutionary success because locomotion is involved with defense, finding mates, and foraging for food in efficient ways. For centuries, biomechanics research has provided a foundation for developing and testing hypotheses ranging from general governing principles of terrestrial locomotion to specific relationships between form and function of limbs and muscles. However, the vast majority of these studies have been conducted in laboratories on treadmills and tracks that bear little resemblance to the environments in which animals actually live. To truly understand the relationship between an animal's muscular and skeletal anatomy and locomotor performance, it is necessary to understand the mechanical demands of the tasks performed in the animal's natural environment. Understanding these relationships in natural habitats remains an important challenge. Therefore, the goal of this study is to examine the relationships between anatomy and locomotor performance through a series of experiments aimed at understanding in detail how different muscles contribute to movement tasks. Experiments will reveal how specific features of muscles and skeletons impact the function of particular muscles during locomotion in mechanically challenging natural environments. The outcomes of this research will advance knowledge about the functional roles of individual muscles, a topic that is rare in comparative biomechanics studies, and lay the groundwork for a better understanding of how mechanical energy is transferred through complex musculoskeletal systems. Application of this knowledge can lead to improvements in the design of autonomous robots, lower limb prosthetics, and other human locomotor enhancement devices.The purpose of this research is to elucidate the relationships between musculoskeletal morphology and bipedal hopping dynamics in desert environments using desert kangaroo rats (D. deserti) as an animal model. It is generally believed that bipedal hopping has evolved because it provides a locomotor performance advantage (e.g., faster top speed, higher endurance, acceleration capacity) related to exaggerated hind limb morphology; however a specific advantage has not been identified for all hopping species. To achieve the proposed objectives, this study will incorporate analyses of habitat use in the field, gait dynamics in the lab, in-vivo muscle dynamics and detailed computer modeling and simulations. This will be the first study to combine all of these methods to provide a comprehensive understanding of the relationships between musculoskeletal morphology and performance. This powerful, integrated approach will be used to pursue two specific research objectives: 1) Quantify the mechanical demands of bipedal hopping on substrates and terrain utilized by D. deserti in their natural environment and, 2) Elucidate the relationship between musculoskeletal morphology and habitat use. The outcomes of the proposed research will establish direct links between locomotor performance under natural conditions and musculoskeletal morphology and muscle function in a way that has not been previously possible. An enhanced understanding of how and why animals hop will advance the fields of evolutionary biology, comparative anatomy, and biomechanics, and lead to improvements in the design of autonomous robots, lower limb prosthetics, and other locomotor enhancement devices. This proposal supports an Educational Plan to develop a field course to provide an opportunity for students to integrate what they have learned about ecology and evolution through research-driven, field-based analyses of habitat use, functional morphology, and behavior. Data for behavior and habitat use from multiple years of this course will provide a broader context for interpreting morphological and biomechanical results.