NSF Postdoctoral Fellowship in Biology FY 2019: Mammals in the water: the loss of mastication in marine carnivores

这项行动资助了2019财年的NSF生物学博士后研究奖学金，扩大了生物学中代表性不足的群体的参与。该研究金支持研究员的一项研究和培训计划，该计划将增加在生物学领域代表性不足的群体的参与。海洋哺乳动物代表了化石记录的教科书范例，记录了随着时间的推移，由生态变化驱动的重大物理变化。为了促进它们从陆地生活到水中生活的过渡，海洋哺乳动物在进食策略上发生了重大变化。食肉海洋哺乳动物缺乏适合咀嚼的专门臼齿：这是陆地哺乳动物的标志。相反，它们的牙齿减少或缺失。返回海洋环境是否会导致食肉哺乳动物齿系的减少和丧失？水下进食时咀嚼是低效的还是无效的？该项目将研究食肉哺乳动物从陆地到海洋过渡的喂养例子，以了解环境的变化如何驱动齿系的变化。该研究员将与密歇根大学古生物学博物馆合作，展示海洋哺乳动物的摄食多样性。该研究员将指导来自代表性不足群体的学生，并制作双语教材，用于教授海洋摄食的演变。回到海洋的哺乳动物经历了戏剧性的形态变化，类似于恐龙的鳞片到羽毛和四足动物的鳍到四肢。这项研究解决了有关哺乳动物摄食系统选择性压力的大规模问题，并将确定咀嚼丧失背后的生态驱动因素：更专业的摄食策略（抽吸，刺穿和过滤器摄食）的关键前体。这项研究将：对牙齿进行形状分析，以量化牙齿表型的多样性，并确定简化的实例（目标-1）;进行穿刺测试，以测量特定牙齿形态的性能（目标-2）;并使用时间校准的系统发育分析将这些结果置于进化背景下（目标-3）。它将测试以下假设：（H1）鲸类和鳍足类会聚在重叠的牙齿表型上;（H2）两个分支独立地简化和减少它们的牙齿随着时间的推移;（H3）每个牙齿表型都能够有效咀嚼;（H4）咀嚼的丧失与牙齿的减少和/或简化暂时相关;（H5）咀嚼功能的丧失是对海洋摄食的一种进化适应。这项研究将整合化石和现代数据，将特定形态与生态性能联系起来，这对于理解复杂结构从简单元素的演变至关重要。该研究员将指导来自代表性不足的群体的学生，并制作双语教材，用于教授海洋喂养的演变。该奖项反映了NSF的法定使命，并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，被认为值得支持。

This action funds an NSF Postdoctoral Research Fellowship in Biology for FY 2019, Broadening Participation of Groups Under-represented in Biology. The fellowship supports a research and training plan for the Fellow that will increase the participation of groups underrepresented in biology. Marine mammals represent textbook examples of the fossil record documenting major physical transformations driven by changing ecology through time. To facilitate their transition from life on land to in the water, marine mammals undergo major shifts in feeding strategies. Carnivorous marine mammals lack the specialized molars adapted for chewing: a hallmark of land mammals. Instead, they have reduced or absent teeth. Does the return to a marine environment select for a reduction and loss of dentition in carnivorous mammals? Is chewing inefficient or ineffective for underwater feeding? This project will study feeding examples across the land to sea transition for carnivorous mammals to understand how changes in environment drive changes in dentition. The fellow will work with the University of Michigan Museum of Paleontology to showcase feeding diversity in marine mammals. The fellow will mentor students from underrepresented groups and produce bilingual educational materials for teaching the evolution of marine feeding. Mammals returning to the ocean undergo dramatic morphological changes akin to scales to feathers in dinosaurs and fins to limbs in tetrapods. This research addresses large-scale questions about selective pressures on mammalian feeding systems and will identify the ecological drivers behind the loss of mastication: a critical precursor to more specialized feeding strategies (suction, piercing, and filter-feeding). This study will: perform shape analyses of teeth to quantify the diversity of dental phenotypes and identify instances of simplification (objective-1); conduct puncture tests to measure the performance of specific dental morphologies (objective-2); and place these results in an evolutionary context using time calibrated phylogenetic analyses (objective-3). It will test the following hypotheses: (H1) cetaceans and pinnipeds converge on overlapping dental phenotypes; (H2) both clades independently simplify and reduce their dentition through time; (H3) each dental phenotype is capable of effective mastication; (H4) the loss of mastication is temporally linked to the reduction and/or simplification of teeth; and (H5) the loss of mastication is an evolutionary adaptation for marine feeding. This research will integrate fossil and modern data to link specific morphologies to ecological performance, which is critical to understanding the evolution of complex structures from simple elements. The fellow will mentor students from underrepresented groups and produce bilingual educational materials for teaching the evolution of marine feeding.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.