Phylogenetic analysis of phenotypic characters and evolutionary transformations in Appendicularia (= Larvacea) and their consequences for the reconstruction of the groundplan of Chordata

附肢动物（=幼虫）表型特征和进化转变的系统发育分析及其对脊索动物纲重建的影响

• 批准号: 451041039
• 负责人: Dr. Thomas Stach
• 金额: --
• 依托单位: Forschungsgruppe Elektronenmikroskopie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/451041039?language=en
• 关键词: Phylogenetic; analysis; phenotypic; characters; evolutionary

Chordata comprises three monophyletic animal taxa: tunicates (= Tunicata), lancelets (= Cephalochordata), and vertebrates (= Craniota). With approximately 2700 species, tunicates show a bewildering diversity of life-history strategies and body plans; many species live attached to the substrate as sessile organisms, others float freely in the plankton, and some display spectacular polymorphisms between generations. Recent phylogenomic and morphology-based phylogenies concur in positioning Appendicularia (= Larvacea) as sister group to the remaining tunicates. This puts Appendicularia with approximately 70 species in a key position to elucidate tunicate evolution, because primitive traits can be expected to occur preferentially in appendicularians. Modern morphological studies are almost exclusively restricted to one species – Oikopleura dioica – impeding a reliable assessment of the disparity within this phylogenetically important group of animals. For the members within the deep-sea genus Bathochordaeus not even light microscopical modern investigations exist. The recent phylogenomic analyses comprise but a single appendicularian species, older molecular phylogenies based on 18S rDNA-sequences included up to three species of a single family. In the proposed project specimens of 13 appendicularian species of all three families will be morphologically analyzed in detail. A major goal is the conceptualization of a data matrix for cladistic analysis based on digital anatomies and immunohistological analyses combined with confocal laser scanning microscopy. Wherever possible, these analyses will be complemented by transmission electron microscopic investigation. In this way, the following goals will be achieved:(1) The morphological disparity of this key taxon will be sampled and documented according to modern standards.(2) Primary homology hypotheses of a maximum number of characters will be formulated.(3) For the first time, a morphology based phylogenetic hypothesis based on a transparent cladistic analysis will be suggested.(4) Hypotheses of the functional morphology of organ systems can be proposed based on the ultrastructural analyses.(5) Evolutionary transformations will be reproducibly explained in all organ systems.(6) A cladistic reconstruction of the ground pattern in the last common ancestor of Appendicularia will be achieved.(7) Implications for evolutionary scenarios of higher taxa Tunicata, Olfactores (= Tunicata + Craniota), and Chordata grounded in these cladistic analyses will be discussed.

脊索动物包括三个单系动物分类群：被囊动物（=被囊动物）、矛形动物（=鲸脊索动物）和脊椎动物（=颅动物）。被囊类约有2700种，它们的生活史策略和身体结构呈现出令人眼花缭乱的多样性;许多物种作为固着生物附着在基底上生活，其他物种在浮游生物中自由漂浮，有些物种在世代之间表现出壮观的多态性。最近的基因组学和形态学为基础的arrhogenies同意在定位Aphellularia（=幼虫）作为姐妹组，其余的被囊动物。这使得约有70个物种的附囊动物处于阐明被囊动物进化的关键位置，因为可以预期原始特征优先发生在附囊动物中。现代形态学研究几乎仅限于一个物种- Oikopleura dioica -阻碍了对这一重要的遗传学动物群体内差异的可靠评估。对于深海属Bathochordaeus的成员，甚至不存在光学显微镜的现代研究。最近的基因组分析包括，但一个单一的approximularian物种，旧的分子遗传学的基础上，18 S rDNA序列，包括多达三个物种的一个单一的家庭。在拟议的项目标本的13个appropriularian物种的所有三个家庭将进行详细的形态分析。一个主要目标是概念化的数据矩阵的分支分析的基础上，数字解剖和免疫组织学分析结合共聚焦激光扫描显微镜。在可能的情况下，这些分析将通过透射电子显微镜研究进行补充。通过这种方式，将实现以下目标：（1）根据现代标准对该关键分类群的形态差异进行采样和记录。(2)最大数量的字符的主要同源性假设将制定。(3)第一次，一个形态学为基础的系统发育假说的基础上，一个透明的分支分析将建议。(4)根据超微结构的分析，可以提出器官系统的功能形态学假说。(5)进化转化将在所有器官系统中得到可重复的解释。(6)在最后一个共同祖先的Apperimularia的地面模式的支序重建将实现。(7)高等类群被囊动物，嗅觉动物（=被囊动物+颅门），并在这些分支分析的脊索动物接地的进化情景的影响进行了讨论。