Complexity in the oldest animal ecosystems

埃迪卡拉期(635-541 Ma)捕捉到复杂生命演化的一个基本阶段。这次的典型代表是埃迪卡拉生物群，这是一个全球分布的大型、软体、形态复杂的多细胞生物群，其生物亲缘关系受到强烈争议。我的研究将数据驱动的建模和先进的仪器设备与实验程序和实地工作结合在一个单一的研究计划中，针对三个基本问题：1)保存在多大程度上偏向早期生命的化石记录？2)埃迪卡拉生物群是如何发挥基本生物学功能的？3)最古老的动物生态系统有多复杂？ 在评估化石记录的保真度时，必须考虑保存偏见。我的研究小组对软组织石化进行了多学科的实验室调查，方法是设计衰变室，持续监测和报告腐烂的地质、生物和化学产物(pH、CO2、H2S、CH4、NO2等)，以及允许以最小破坏进行采样的沉积物/液体/气体提取工具。通过这种方法，我们能够识别异常石化的节奏和模式中的关键阶段，并对早期生命化石记录的保真度设定现实的限制。 为了解决Ediacara生物群的生物学功能，我将系统发育研究与功能形态相结合。我的研究小组率先使用数字重建处于虚拟海洋条件下的埃迪卡拉生物来展示替代的进食策略，甚至提出了没有化石附肢的形式的流动性。我的方法以单个物种如何在生态系统中相互作用为目标，导致对埃迪卡拉生态系统中隐藏的复杂性的评估。 由于生态系统的复杂性可以用多种方式来研究，我的实验室开发了创新的模糊生态空间建模方法，目标是生物在生态系统(即生态位)中的进化、扩展，甚至是战略地位的丧失。考虑到它们的古老，埃迪卡拉生态系统通常被解释为相对简单。然而，从我的研究中衍生出来的古生态研究表明，1)许多埃迪卡拉生物群之间的竞争性相互作用导致物种形成的可能性，2)最古老的埃迪卡拉生物群之间扩大的繁殖策略，3)随着穿透性洞穴和捕食的出现，最新的埃迪卡拉生物群的营养结构扩大，以及4)移动的埃迪卡拉生物群比先前假设的更大的多样性。纳米比亚和伊朗的有针对性的实地项目将提供必要的数据，以评估整个埃迪卡拉纪和寒武纪的生态位创造、占领和破坏是如何变化的。最终，我的研究将是评估生物相互作用和动物生命黎明时更替的规模的核心。

The Ediacaran Period (635-541 Ma) captures a fundamental stage in the evolution of complex life. Typifying this time are the Ediacara biota, a globally distributed group of large, soft-bodied, morphologically complex multicellular organisms whose biological affinities are strongly contested. My research combines data-driven modeling and advanced instrumentation with experimental procedures and field work into a single research program targeting three fundamental questions: 1) to what extent is preservation biasing the fossil record of early life? 2) How did the Ediacara biota perform basic biological functions? And 3) how complex were the oldest animal ecosystems? Preservational biases must be considered when evaluating the fidelity of the fossil record. My research group applies multidisciplinary laboratory-based investigations into soft-tissue fossilization by designing decay chambers that continuously monitor and report the geological, biological, and chemical products of decay (pH, CO2, H2S, CH4, NO2, etc.), in addition to sediment/liquid/gas extraction tools that allow for sampling with minimal disruption. Through this approach, we are able to identify key stages in the tempo and mode of exceptional fossilization, and set realistic limits on the fidelity of the fossil record of early life. In order to address the biological functions of the Ediacara biota, I combine phylogenetic studies with functional morphology. My research group has pioneered the use of digital reconstructions of Ediacaran organisms subjected to virtual oceanic conditions to demonstrate alternative feeding strategies and even propose mobility in forms that lack fossilized appendages. My approaches target how individual species interacted within an ecosystem, leading to evaluations of the hidden complexity within Ediacaran ecosystems. As ecosystem complexity can be investigated in many ways, my laboratory has developed innovative fuzzy ecospace modelling approaches that target the evolution, expansion, and even loss of strategic positions occupied by organisms within an ecosystem (i.e. niche). Given their antiquity, Ediacaran ecosystems are typically interpreted as relatively simple. However, paleoecological studies stemming from my research have demonstrated 1) the likelihood of competitive interactions between many Ediacara biota leading to speciation, 2) expanded reproductive strategies among the oldest Ediacara biota, 3) expanded trophic structure in the latest Ediacaran with the advent of penetrative burrowing and predation, and 4) a greater diversity of mobile Ediacara biota than previously hypothesized. Targeted field programs in Namibia and Iran will provide the data necessary to evaluate how niche creation, occupation, and destruction has changed throughout the Ediacaran and into the Cambrian. Ultimately, my research will be central to evaluating the magnitude of biotic interactions and turnover at the dawn of animal life.