Pinning down the phylogenetic position of Chaetognatha: architecture of their nervous system in comparison to potential outgroups

我们分析毛颌鱼的神经系统的进化背景，以提供新的见解，以系统发育的位置，这一分类单元（神经系统发育）。在本申请中，我们全面报告了SPP 1174“深层后生动物系统发育”第2阶段的工作进展，包括SPP中所有神经系统发育组的联合活动，如建立无脊椎动物神经解剖学术语表。我们申请第三阶段的主要目标是最终确定毛颌动物的系统发育位置。为此，我们建议将第三阶段工作的大约60%用于获取额外的神经解剖学数据，以填补在第一阶段和第二阶段变得明显的知识空白。大约40%的第三阶段工作将与其他神经系统发育组一起在联合数据矩阵中分析数据，并对形态学数据进行综合分析。更准确地说：1；由于到目前为止，我们只分析了两种毛齿鱼，我们建议扩大分类群取样范围，对其大脑结构和腹侧神经中枢可识别的神经元的排列进行广泛的比较分析，以得出毛齿鱼的代表性神经系统基础模式，为后续与其他原口动物分类群的系统发育分析和神经系统特征的正确编码奠定坚实的基础。此外，该方法将有助于研究毛齿动物的内部系统发育。2. 我们建议使用我们已经成功用于毛齿动物的全套标记来研究毛齿动物的神经系统，这是毛齿动物潜在的外类群。目的是在这个分类单元的地面模式中获得神经系统的稳定重建。这种方法对于填补矩阵神经原子数据集的现有空白至关重要，并将允许立即测试尼尔森（2001）提出的Gnathifera假说，其中毛颌类被认为是Gnathostomulida， Rotatoria和其他Gnathifera分类群的亲戚。3. 优先计划的最终目标之一是对DMP合作者编制的所有形态学数据进行综合分析，第二步是形态学和分子数据的结合。神经系统发育小组的分析将主要集中在我们亲自研究过的结构上。我们创新的数据分析方法的其他方面包括严格术语的发展和关键的字符概念化，包括对这些概念化字符的初级同源性测试。我们已经在第二阶段建立了无脊椎动物的神经解剖学术语表，从而发展了这样一个术语。形态学数据库MorphDBase在优先项目内不同形态学项目的联锁以及管理和促进组合形态学特征矩阵的生成中起着中心作用。为了建立角色矩阵，我们还将与“Protostome Tree of Life”AtoL小组的参与者进行互动。

We analyse the nervous system of Chaetognatha against an evolutionary background in order to provide new insights into the phylogenetic position of this taxon (Neurophylogeny). In this application, we thoroughly report our work progress during Phase 2 of SPP 1174 „ Deep Metazoan Phylogeny“ including joint activities of all Neurophylogeny groups in the SPP such as establishing a glossary of neuroanatomical terms in invertebrates. The major goal of our application for Phase 3 is to finally pin down the phylogenetic position of Chaetognatha. To that end, we suggest dedicating circa 60% of the Phase 3 work efforts to obtaining additional neuroanatomical data to fill gaps of knowledge that became obvious during Phase 1 and 2. Circa 40% of the Phase 3 work efforts will be directed towards the analysis of the data together with the other neurophylogeny groups in a joint data matrix and a combined analysis of morphological data. More precisely: 1. Because so far we have analyzed only two chaetognath species, we suggest extending the taxon sampling for a broad comparative analysis of brain structure and arrangement of individually identifiable neurons in the ventral nerve centre in order to work out the representative nervous system ground pattern of Chaetognatha as a solid basis for the following phylogenetic analysis with other protostomian taxa and for the correct coding of nervous system characters in the matrix. Furthermore, this approach will contribute characters to resolve chaetognath internal phylogeny. 2. We propose to use the full set of markers that we have already successfully used for the Chaetognatha to study the nervous system of Gnathostomulida, a potential outgroup of Chaetognatha. The aim is to obtain a stable reconstruction of the nervous system in the ground pattern of this taxon. This approach will be vital to fill the existing gaps in the neuronatomical data set for the matrix and will allow for an immediate test of the Gnathifera hypothesis as suggested by Nielsen (2001) in which the Chaetognatha are suggested to be relatives of Gnathostomulida, Rotatoria and other gnathiferan taxa. 3. One of the ultimate goals of the priority program is a combined analysis of all the morphological data compiled by the DMP collaborators, and in a second step the combination of morphological and molecular data. The analysis of the Neurophylogeny team will focus on structures which, primarily, we have studied in person. Other aspects of our innovative approach of data analysis include the development of a strict terminology and the critical conceptualization of characters, including a test of primary homology for these conceptualized characters. We have already development such a terminology by establishing a glossary of neuroanatomical terms for invertebrates in Phase 2. The morphological database of DMP, MorphDBase takes on a central function in the interlocking of the different morphological projects within the priority program and managing and facilitating the generation of a combined morphological character matrix. For establishing the character matrixs we will also interact with participants of the “Protostome Tree of Life” AtoL group.