Craniofacial Biomechanics in Camelids: In vivo and Comparative Studies in Form and Function

骆驼的头面部生物力学：形态和功能的活体和比较研究苏珊·H·威廉姆斯俄亥俄大学骨科医学院哺乳动物的咀嚼或咀嚼器官为了解灭绝和活着的哺乳动物的进化、行为、饮食和生态提供了一个窗口。以前的研究已经深入到这些领域，为哺乳动物的咀嚼形式提供了适应性、功能性和生物力学方面的解释。本研究以羊驼(Lama Pacos)和山羊(Capra Hircus)为模型，采用综合分析的方法来研究反胃或咀嚼偶蹄动物时饲喂器具的形态与功能之间的关系。将使用肌电图仪来记录颌肌的行为，使用应变仪技术来了解下颌和面部骨骼是如何在外力的作用下加载的，并使用视频记录来记录由于颌骨肌肉收缩而产生的颌骨运动，从而探索咀嚼和其他进食行为的动力学。这些数据将与口腔行为数据以及来自解剖、组织分析和成像研究的比较解剖学和形态学数据相结合。这项研究的一个主要组成部分将集中在摄食动力学和咀嚼器官的解剖如何随着摄食行为和消化生理的正常个体发育变化而变化。由于包括兔子和猪在内的非反胃哺乳动物也有类似的数据，因此将对不同物种进行比较，以突出与消化策略相关的咀嚼器官发展中可能的适应和限制。在这项研究中收集的数据也将被用来解决关于颌骨形态和生长之间关系的假设，在其常规功能环境的背景下。在羊驼和山羊身上，这种功能环境由高度重复的咀嚼行为组成，与反省相关的咀嚼行为在三到四个月大的时候就开始了，很久以前就达到了成年的咀嚼形态。有趣的是，羊驼及其近亲在成年下巴形态上不同于山羊和所有其他反胃的偶蹄目动物。在前者中，下颌骨两半之间的关节在个体发育过程中早期骨化，而在后者中，该关节在一生中保持开放和活动。这些差异被认为与下颌负荷环境的差异与成人咀嚼行为有关。因此，这项研究将检验关于重复性机械因素与下颌结构和发育差异的作用的假设。这项研究的更广泛的影响包括为研究生生涯开始的少数族裔女科学家PI提供额外的培训，以及为俄亥俄(OU)和俄亥俄州立大学(OSU)的本科生和研究生提供跨学科的教育和培训机会。这些学生将接受实验和比较功能形态和生物力学的方法论和概念方法方面的培训。学生还将参与传播这项研究的结果，方法是在专业会议上发表演讲，并在生物力学、进化和功能形态以及古生物学领域的专业期刊上合作发表文章。最后，这项研究计划将通过为体内和体外菌株分析提供基础设施和专业知识，并通过这笔赠款加强俄亥俄大学和俄亥俄州立大学之间的学术和研究关系，扩大俄亥俄大学的功能形态学和生物力学培训的范围。

Craniofacial biomechanics in camelids: in vivo and comparative studies in form and functionSusan H. WilliamsOhio University College of Osteopathic MedicineThe mammalian masticatory or chewing apparatus provides a window into the evolution, behavior, diet and ecology of extinct and living mammals. Previous research has tapped into each of these realms to offer adaptive, functional and biomechanical explanations of mammalian masticatory form. In this study, an integrative approach will be used to understand the relationship between form and function of the feeding apparatus in ruminating, or cud-chewing, artiodactyls using alpacas (Lama pacos) and goats (Capra hircus) as models. The dynamics of mastication and other feeding behaviors will be explored using electromyography to record the behavior of jaw muscles, strain gauge techniques to understand how the mandible and facial skeleton are loaded by external forces, and video recordings to document jaw movements produced by contraction of the jaw muscles. These data will be integrated with data on oral behaviors and with comparative anatomical and morphological data derived from dissections, histological analyses and imaging studies.A major component of this study will focus on how feeding dynamics and the anatomy of the masticatory apparatus change in concert with normal ontogenetic changes in feeding behavior and digestive physiology. As similar data are available for non-ruminating mammals, including rabbits and pigs, comparisons will be made across species to highlight possible adaptations and constraints in the development of the masticatory apparatus associated with digestive strategies. Data collected in this study will also be used to address hypotheses regarding the relationship between jaw form and growth in the context of its routine functional environment. In alpacas and goats, this functional environment consists of highly repetitive chewing behaviors associated with rumination beginning around three to four months of age, well before adult masticatory morphology is attained. Interestingly, alpacas and their close relatives differ from goats and all other ruminating artiodactyls in adult jaw morphology. In the former, the joint between the two halves of the mandible ossifies early during ontogeny whereas in the latter this joint remains patent and mobile throughout life. These differences are thought to be related to differences in loading environment of the mandible associated with adult masticatory behaviors. Thus, this study will test hypotheses regarding the role of repetitive mechanical factors in relation to differences in structure and growth of the mandible.The broader impacts of this study include additional training for the PI, a minority female scientist at the start of her post-graduate career, and interdisciplinary educational and training opportunities for undergraduate and graduate students at two universities, Ohio (OU) and Ohio State University (OSU). These students will receive training in methodological and conceptual approaches in experimental and comparative functional morphology and biomechanics. Students will also participate in disseminating the results of this study by presenting at professional meetings and collaborating on publications for professional journals in the fields of biomechanics, evolutionary and functional morphology, and paleontology. Finally, this research program will broaden the scope of functional morphology and biomechanics training at Ohio University by contributing infrastructure and expertise for in vivo and in vitro strain analysis and by enhancing academic and research relationships between OU and OSU through this grant.