Collaborative Research: Oxygen, Ecology and the Cambrian radiation of Animals

合作研究：氧气、生态和动物的寒武纪辐射哈佛大学戴维·约翰斯顿和斯克里普斯海洋研究所丽莎·莱文5.4亿年前的寒武纪辐射是地球历史上最重要的进化事件之一，在此期间，所有主要的动物身体结构都出现在化石记录中。近年来，这一事件的假设触发因素集中在捕食行为的增加和世界海洋中氧气含量的增加上。我们建议检验这些假设之间的联系。我们假设食肉动物（以动物为食的动物）的高需氧量是关键的联系。该假说概述了食肉动物（动物吃其他动物）受到低水平大气氧气的限制。随着前寒武纪晚期的地球过渡到更含氧的状态，这种生活方式（食肉）和最终的寒武纪大爆发随之而来。在这里，我们将测试这一假设的生物学和地质学预测。氧气限制动物食肉性的生物学预测，将通过构建和分析一个已发表的海洋底栖动物调查数据库，对每种动物的进食方式进行编码，并检查氧气水平和其他环境参数如何影响进食行为来验证。在加拿大西北部的Ogilvie、Wernecke和Mackenzie山脉的壮观新元古代地层记录中，通过生成沉积地球化学数据（重点是铁、碳和硫），将主要对氧气在前寒武纪-寒武纪边界附近增加的地质预测进行验证。总之，这两项对寒武纪辐射的综合因果假设的测试将为这一重要的地质生物学事件提供新的见解。这项拨款为培养两个层次的研究人员提供资金。首先，该基金将为一名博士后学者提供资金，该学者将在斯克里普斯和哈佛大学的首席研究员之间工作，以实现该提案的目标。这位博士后学者还将与海洋科学教育卓越中心合作，在伯奇水族馆的海洋科学展望系列中发表一篇公开演讲。这些讲座广泛分发（每年向1500万家庭广播，约20万次网络观看），将有助于向公众传播现代全球海洋汇编的结果，并展示古代海洋如何为应对现代海洋学变化提供信息。第二，两名本科生，一名来自哈佛大学，另一名来自本科院校，将通过这项资助获得加拿大西北部的实地经验和沉积地球化学的实验室经验。

Collaborative Research: Oxygen, Ecology and the Cambrian radiation of AnimalsDavid Johnston, Harvard UniversityLisa Levin, Scripps Institute of OceanographyThe Cambrian radiation, during which essentially all major animal body plans appeared in the fossil record ~540 million years ago, is one of the most important evolutionary events in Earth history. In recent years, hypothesized triggers for this event have focused on a rise in predation and increased levels of oxygen in the world's oceans. We propose to test the linkage between these hypotheses. We postulate that the high oxygen demand of carnivory (animals feeding on animals) is the key linkage. The hypothesis outlines that carnivory (animals eating other animals) was limited by low levels of atmospheric oxygen. As the late Precambrian Earth transitioned to a more oxygenated state, this lifestyle (carnivory) and ultimately the Cambrian explosion ensued. Here, we will test both the biological and geological predictions of this hypothesis. The biological prediction, that oxygen limits carnivory in animals, will be tested by constructing and analyzing a database of published marine bottom dwelling animal surveys, coding how each animal feeds, and examining how oxygen levels and other environmental parameters affect feeding behavior. The geological prediction, that oxygen increased near the Precambrian-Cambrian boundary, will primarily be tested by generating sedimentary geochemical data (focusing on iron, carbon and sulfur) from the spectacular Neoproterozoic stratigraphic record of northwestern Canada in the Ogilvie, Wernecke and Mackenzie Mountains. Together, these two tests of this integrative causal hypothesis for the Cambrian radiation will provide new insight into this important geobiological event. This grant provides funding to train two levels of researchers. First, the grant provides funding for a post-doctoral scholar who will work between the Principal Investigators at Scripps and Harvard to accomplish the goals of the proposal. The post-doctoral scholar will also will work with the Center for Ocean Sciences Education Excellence to deliver a filmed public lecture in the Perspectives on Ocean Sciences series at the Birch Aquarium. These are widely distributed talks (broadcast to 15 million homes; ~200,000 web views per year) and will be instrumental in disseminating the results of the modern global ocean compilation to the public and demonstrating how ancient oceans can inform responses to modern oceanographic change. Second, two undergraduate students, one from Harvard and one from an undergraduate-oriented institution, will gain both field experience in northwest Canada and lab experience in sedimentary geochemistry through this grant.