CAREER: Evolutionary biomechanics and functional morphology of salamander locomotion

职业：蝾螈运动的进化生物力学和功能形态

• 批准号: 2340080
• 负责人: Sandy Kawano
• 金额: $ 106.7万
• 依托单位: George Washington University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-07-01 至 2029-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2340080&HistoricalAwards=false
• 关键词: CAREER; Evolutionary; biomechanics; functional; morphology

How tetrapods, four footed animals, became terrestrial was a pivotal event in vertebrate evolution that set the stage for the diversification of tetrapods thereafter. The locomotor capabilities of early tetrapods are often modeled with extant salamanders since the latter have a generalized tetrapod body plan. Yet, salamanders exhibit tremendous morphological diversity across environments, providing a framework to assess the mechanical requirements for terrestrial locomotion by comparing morphological change across carefully matched evolutionary lineages. The greater effects of gravity may impose biomechanical constraints that preclude certain salamanders from moving on land, but the habitat that salamanders occupy differs between developmental strategies. Metamorphosis involves the development of an animal across two or more distinct life stages but can be biphasic (aquatic larvae to terrestrial adults) or multi-phasic (aquatic larvae to terrestrial juveniles to aquatic adults) whereas direct development remains in one environment. Thus, biomechanical constraints may be stronger in terrestrial direct developers than biphasic metamorphers since the former do not experience an aquatic stage. This project will integrate physiology, engineering, and evolutionary biology to examine how the interplay between habitat preference and developmental strategy affects the relationship between the structure and function of tissues (e.g., bones) and whole-organism performance (e.g., locomotion). Students will receive research training through a new Course-Based Undergraduate Research Experience on Organismal Form and Function and Professional Research Experience for Post-baccalaureates in Biology program to broaden the participation of learners from historically excluded communities. In addition, “Salamander Safaris” will be hosted during Amphibian Week to promote the participation of girls in STEM. Locomotion places some of the highest physical demands (‘loads’) on bones and failure to withstand loads could cause fractures or even death in an animal, yet how bones evolved to support the loads imposed by aquatic vs. terrestrial environments is not well understood. Phylogenetic comparisons of whole-bone mechanics across ecologically diverse species will advance knowledge of how habitat and developmental strategy has shaped the evolutionary morphology of salamander limb bones. Investigators will quantify in vivo bone loading during terrestrial walking through synchronized 3D kinematics and kinetics. Investigators will then apply these loading data to collect the first dynamic measures of limb bone strength by integrating mechanical property testing and 3D digital image correlation. Finally, they will combine these techniques to examine how bone mechanics is affected by water-land and land-water transitions within a lifetime by comparing juveniles and adults from species with different developmental strategies (i.e., direct, biphasic, multiphasic). Bone strength is predicted to be highest in terrestrial direct developers lowest in paedomorphic aquatic salamanders, and intermediate in biphasic metamorphic salamanders. Stronger bones likely assist terrestrial species to withstand internal (muscle) and external (ground reaction forces) loads and then transfer this energy into propulsion. Compared to the femur, the humerus is expected to evolve at faster rates based on the multi-functional role of forelimbs (e.g., digging, reproduction, locomotion) that is likely less constrained compared to hindlimbs whose primary role is for generating propulsion. Findings from this work will contribute new insights into the mechanical requirements of becoming terrestrial.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

四足动物如何变成陆地动物是脊椎动物进化中的一个关键事件，为此后四足动物的多样化奠定了基础。早期四足动物的运动能力通常以现存的蝾螈为模型，因为后者有一个广义的四足动物身体计划。然而，蝾螈在不同的环境中表现出巨大的形态多样性，通过比较仔细匹配的进化谱系的形态变化，提供了一个评估陆地运动机械要求的框架。重力的更大影响可能会施加生物力学限制，阻止某些蝾螈在陆地上移动，但蝾螈占据的栖息地因发育策略而异。变态涉及动物跨越两个或两个以上不同生命阶段的发育，但可以是双相的（水生幼虫到陆生成虫）或多相的（水生幼虫到陆生幼体到水生成虫），而直接发育仍然在一个环境中。因此，生物力学约束可能是更强的陆生直接开发商比双相变质，因为前者没有经历水生阶段。该项目将整合生理学，工程学和进化生物学，以研究栖息地偏好和发育策略之间的相互作用如何影响组织结构和功能之间的关系（例如，骨）和整个生物体性能（例如，运动）。学生将通过一个新的课程为基础的本科生研究经验的有机体的形式和功能和专业研究经验后学士学位在生物学计划接受研究培训，以扩大从历史上被排斥的社区学习者的参与。此外，“蝾螈之旅”将在两栖动物周期间举办，以促进女孩参与STEM。运动对骨骼提出了一些最高的物理要求（“负载”），无法承受负载可能导致动物骨折甚至死亡，但骨骼如何进化以支持水生环境与陆地环境施加的负载尚不清楚。系统发育比较生态多样的物种的全骨力学将推进栖息地和发展战略如何塑造蝾螈肢骨的进化形态学的知识。研究者将通过同步的3D运动学和动力学量化在陆地行走期间的体内骨负荷。然后，研究人员将应用这些载荷数据，通过整合力学性能测试和3D数字图像相关性来收集肢体骨强度的第一个动态测量值。最后，他们将联合收割机结合这些技术，通过比较具有不同发育策略（即，直接的、双相的、多相的）。骨强度预测是最高的陆地直接开发者最低的幼态水生蝾螈，和中间的双相变质蝾螈。更强壮的骨骼可能有助于陆地物种承受内部（肌肉）和外部（地面反作用力）负荷，然后将这种能量转化为推进力。与股骨相比，基于前肢的多功能作用（例如，挖掘、繁殖、运动），其与主要作用是产生推进力的后肢相比可能较少受到限制。这项工作的结果将有助于对陆地机械要求的新见解。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。