Doctoral Dissertation Improvement: The Influence of development and homology on hominin molar morphological diversity

------博士论文改进：发育和同源性对古人类臼齿形态多样性的影响牙齿特征经常用于古人类（人类及其化石近亲）的物种诊断和系统发育重建。对牙齿的研究也在重建古人类饮食，以及最近人类种群之间的生物关系方面发挥了重要作用。然而，牙齿的变异不仅是系统发育和功能相互作用的结果，而且是控制牙齿形态发生的发育过程的结果。有趣的是，发育在古人类牙列形态多样性中的作用通常被忽视。由博士候选人Alejandra Ortiz（纽约大学）在Shara Bailey博士的指导下进行的研究将调查人类牙齿形态的进化是如何形成的。具体来说，该项目将检查从大量臼齿样本中提取的几个牙齿特征，以探索同源性的发展基础（定义为由于共同祖先而产生的相似性），并确定我们谱系成员的发育整合模式。通过检查特征同源性和独立性，这种综合方法将试图识别高系统发育价的牙齿特征，并帮助解决与过去人类系统发育假设的模糊性相关的人类学长期问题。发育信息的使用也将有助于未知古人类标本的分类鉴定。高分辨率微计算机断层扫描（microCT）将分别用于牙釉质-牙本质交界处和牙釉质外表面的牙齿内表面和外表面的可视化。这项研究将在大约500个臼齿上进行，这些臼齿被分配给来自泛人属、南方古猿、类人猿和人属的许多物种。数据将通过视觉评估、三维几何形态计量学、线性测量和面积测量进行定性和定量分析。该项目将促进科学界的国际合作，并为本科生提供培训机会。对该项目的支持将鼓励生物科学领域的多样性，因为共同负责人是一名来自科学界代表性不足群体的女性。重要的是，该项目将有助于开发微型ct扫描的虚拟集合，其使用将最大限度地减少数据收集错误，并限制对脆弱化石材料的操纵。这些微型ct扫描将根据与参与博物馆的个别协议向公众开放。此外，从这个项目中获得的度量数据将在网上免费提供。由于与人类进化有关的问题是公众广泛关心的问题，这项研究的结果将在学术会议上提出，并在技术和大众出版物中传播。该项目将寻求在多个研究领域之间建立联系，包括牙科人类学、古人类学、系统学和进化发育生物学。

------Award Abstract #1341148Doctoral Dissertation Improvement: The Influence of development and homology on hominin molar morphological diversityDental features are frequently used in species diagnoses and phylogenetic reconstructions of hominins (humans and their fossil relatives). The study of teeth has also played an important role in reconstructing hominin diets, as well as biological relationships among recent human populations. However, dental variation is the result of not only phylogenetic and functional interactions, but also the developmental processes controlling tooth morphogenesis. Interestingly, the role of development on the morphological diversity in the hominin dentitions has generally been overlooked. Research by doctoral candidate Alejandra Ortiz (New York University), under the supervision of Dr. Shara Bailey, will investigate how development has shaped the evolution of hominin tooth forms. Specifically, this project will examine several dental traits drawn from a large sample of molars in order to explore the developmental basis of homology (defined as similarity due to common ancestry) and determine patterns of developmental integration in members of our lineage. By examining trait homology and independence, this integrative approach will attempt to identify dental features of high phylogenetic valence and help solve the long-standing problem in anthropology associated with the ambiguity of past hominin phylogenetic hypotheses. The use of developmental information will also contribute to the taxonomic identification of unknown hominin specimens.High-resolution micro-computed tomography (microCT) will be used to visualize the internal and external surface of teeth at the enamel-dentine junction and outer enamel surface, respectively. This research will be undertaken in approximately 500 molars assigned to a number of species from the genera Pan, Australopithecus, Paranthropus and Homo. Data will be analyzed both qualitatively and quantitatively via visual assessments, three-dimensional geometric morphometrics, and linear and area measurements.This project will promote international collaboration within the scientific community and provide training opportunities for undergraduate students. Support for this project will encourage diversity within the biological sciences, as the co-PI is a female from an underrepresented group in science. Importantly, this project will contribute to the development of a virtual collection of microCT scans, the use of which will minimize data collection errors and limit the manipulation of fragile fossil material. These microCT scans will be available for public access according to individual agreements with participating museums. Furthermore, metric data derived from this project will be made freely available online. Since questions related to human evolution are of broad public interest, results of this study will be presented at academic conferences, as well as disseminated in technical and popular publications. This project will seek to create linkages among multiple fields of research, including dental anthropology, paleoanthropology, systematics and evolutionary developmental biology.