Collaborative Research: Systematics and Adaptation of the Thaliacea (Tunicata): A Genetic and Morphological Study

海樽纲（Thaliacea）是被囊动物的一个纲，包括三组远洋被囊动物，Pyrosomida，Doliolida和Salpida。它们都是自由游动的全浮游生物，有着复杂的生活史和惊人的能力，就像浮游生物中的滤食草食动物一样。这三个目分布于世界各地，但总共不到100种。在某些情况下，表型变异混淆了以前的系统分类工作，并在许多看似世界性的形式中留下了隐藏物种的可能性。现有的分类和系统发育都是基于数量有限的形态特征，这已经不足以解决许多问题的属和种的水平上的关系。初步的遗传证据表明，海樽纲是单系内的被囊纲和海鞘，doliolids和pyrosomes是很好的约束单系的目的。然而，序数以下的关系尚不清楚，经典和分子树之间已经出现了一些冲突。尽管海樽纲分布于全球，具有明显的生态学意义，但今天很少有科学家从事海樽纲生物学的任何方面的研究。部分原因可能是非专业人员难以识别物种，特别是因为标本经常在收集过程中损坏。该项目汇集了两名分子动物学家和一名海樽纲动物生态学和生活史专家。该研究小组将寻求协调形态和遗传数据，以根据所描述的尽可能多的物种的数据（可能至少70%），为海樽纲动物开发一个系统发育。由于这些群体相当小，这是一个可行的目标，不仅可以实现一个得到充分支持的共识系统发育和分类，而且还可以对纲进行专题处理，这对非专家的物种鉴定很有用。拟议研究的更广泛影响包括为全球海洋浮游动物普查提供成果，并为生物海洋学家提供海樽纲的实用识别指南。该项目将支持WHOI的博士后研究员，并涉及康涅狄格大学的本科生。项目目标和结果将通过世界卫生组织或康涅狄格大学的一个或多个网站广泛提供。

The Thaliacea is a class of Tunicata comprising three groups of pelagic tunicates, the Pyrosomida, Doliolida and Salpida. All are free-swimming holoplanktonic organisms with complex life histories and prodigious capabilities as filter-feeding herbivores in the plankton. These three orders have worldwide distributions yet together number fewer than 100 described species. In some cases phenotypic variability has confused prior efforts at systematic classification and left open the possibility of cryptic species among many seemingly cosmopolitan forms. Existing classifications and phylogenies are all based on a limited number of morphological characters, which have been inadequate to resolve many questions about relationships at the genus and species level. Preliminary genetic evidence suggests that the Thaliacea are monophyletic within the Tunicata andthat salps, doliolids and pyrosomes are well-constrained monophyletic orders. However relationships below the ordinal are unclear, with some conflicts already arising between classical and molecular trees. Despite their global distribution and apparent ecological significance there arefew scientists today working on any aspect of Thaliacean biology. Partly this may be due to the difficulty for non-specialists in identifying species, particularly as specimens are often damaged in collection. This project brings together two molecular zoologists and one expert in Thaliacean ecology and life history. The research team will seek to reconcile morphological and genetic data to develop a phylogeny for the Thaliacea, based on data from as many of the described species as can be obtained, probably at least 70%. Because these groups are fairly small, this is a feasible goal, and will enable not only a well-supported consensus phylogeny and classification, but also a monographic treatment of the Class that will be useful for species identification by nonexperts. Broader impacts of the proposed research include the contribution of results to the global Census of Marine Zooplankton and the provision of a practical identification guide to Thaliacea for biological oceanographers. The project will support a postdoctoral investigator at WHOI and involve undergraduate students at the University of Connecticut. Project objectives and results will be made widely available via one or more websites hosted at WHOI or the University of Connecticut.