A can of worms-tracing the origins of Ecdysozoa using fossils, molecules and morphology in a Bayesian framework

外生动物包括一些最成功的无脊椎动物门，如节肢动物和线虫。然而，这一群体的其他成员今天的数量比以前少了。一个惊人的化石记录，重点是新收集的早寒武纪天狼星帕塞特的材料，可能为更好地了解祖先外生动物的性质以及这些不同的化石蠕虫与现有同类动物的关系提供了手段。人们一直在争论，这些蠕虫化石是属于这棵树的不同分支，还是主要属于它们最相似的一类，即原杆类。本项目将寻求整合化石、形态学和分子序列数据来研究外生动物的系统发育和进化。在格陵兰岛北部偏远的天狼星帕塞特发现了许多新的化石。这些新化石具有看不见的特征，可能有助于更好地了解古球虫的性质及其与生活群体的关系。以这些化石为模板，我们将探索来自不同地点的化石记录，并将它们的解剖学与现代形式进行汇编，以探索它们的系统发育位置。此外，我们将探索结合形态、分子和化石与地层年龄来共同估计系统发育和分化时间，这可能有助于揭示可能导致化石分类群错误位置的趋同进化的发生率。在思考外生动物进化的框架内，有几个层次的自由，学生可以探索不同的主题，并将项目带到新的方向。这包括探索和描述新的分类群，开发可视化和重建化石的方法，开发系统发育方法或在其他生物群体上进行比较和对比的测试方法。欢迎对项目如何发展和发展有个人观点的学生。该项目由来自布里斯托尔、巴斯、自然历史博物馆和KOPRI的主管组成。所有人都有关于动物群体和使用方法的专业知识。这些主管为讨论发现和指导候选人提供了丰富的智力和经验资源。巴斯和自然历史博物馆的邻近意味着学生将能够定期与这些导师见面，英国团队可以很容易地聚集在一起进行一天的活动来讨论这个项目。KOPRI的导师可能会去英国参加这样的聚会，但学生和首席导师会定期访问韩国，研究他们收藏的化石材料。自然历史博物馆收藏了现存的材料和化石标本，在编制系统发育分析的解剖矩阵时，可以提供有用的比较和研究。培训学生将花时间调查这些化石，学习如何解释化石，并尽可能多地利用成像技术，相机lucida绘图和元素映射揭示解剖结构。此外，学生将熟练使用R和Linux shell界面进行命令提示。该学生将前往韩国进行一段较长时间的学习。还建议参观博物馆，研究其他地方的藏品。

Project Background Ecdysozoans comprise some of the most successful invertebrate phyla, such as the arthropods and nematodes. However, other members of the group are less abundant today than they used to be. An amazing fossil record with a focus on newly collected material from the Early Cambrian Sirius Passet may provide means to better understand the nature of the ancestral ecdysozoan and how these many different fossil worms are related to their extant counterparts. It has been debated whether many of these vermiform fossils are subtending various branches of the tree or mainly the group that they resemble the most, the priapulids. This project will seek to integrate fossils, morphology and molecular sequence data to investigate the phylogeny and evolution of the Ecdysozoa. Project Aims and Methods Many new fossils have been discovered in the remote Sirius Passet in North Greenland. These new fossils feature unseen characters that may be useful in better understanding the nature of palaeoscolecid worms and their affiliation to living groups. Using these fossils as a template, we will explore the fossil record from different sites and compile their anatomy with modern forms to explore their phylogenetic placement. Furthermore, we will explore the use of combined morphology, molecules and fossils with stratigraphic ages to co-estimate phylogeny and divergence times which may help reveal incidences of convergent evolution that can result in erroneous placements of fossil taxa. Within the framework of thinking about Ecdysozoan evolution there are several levels of freedom within the student can explore different subject and take the project in new directions. These can range from exploration and description of new taxa, developing methods for visualization and reconstruction of fossils, development of phylogenetic methods or testing methods on other groups of organisms to compare and contrast with. A student with a personal perspective on how the project could evolve and develop is much welcomed. Project partners The project features supervisors from Bristol, Bath, The Natural History Museum and KOPRI. All have expertises on the group of animals and the methods used. These supervisors provide for a wealth of intellectual and experiential resource for discussion of findings and mentorship to the candidate. The proximity of Bath and the Natural History museum means that the student will be able to regularly meet these supervisors in person and the British team can easily gather for one day events to discuss the project. The supervisors at KOPRI may visit England for such gatherings, but the student and the lead supervisor will regularly visit South Korea to work on fossil material held in their collections. The Natural History Museum holds collections of extant material along with fossil specimens that may provide for useful comparisons and study when compiling the anatomical matrix for phylogenetic analysis. Training The student will be spending time investigating these fossils and learning how to interpret the fossils and reveal as much anatomy as possible using imaging techniques, camera lucida drawings and elemental mapping. Furthermore, the student will become proficient in using R and Linux shell interface for command-prompting. The student will travel to South Korea for some extended periods to work on material held there. Museum visits to study collections from other localities is also recommended.