AnnEvol - Evolution and phylogeny of Annelida based on phylogenomic data (i.e. EST libraries)

环节动物是一种古老而多样的动物类群，栖息在从深海到陆地土壤的不同栖息地。环节动物是三大分节动物类群之一，解读环节动物的进化对于我们理解分节的进化至关重要。传统上，环节动物包括多毛类（例如，沙虫）和环带虫（例如，蚯蚓和水蛭）。虽然在多毛纲中的Clitellata的位置得到了很好的支持，但它们的多毛类姐妹群是不确定的。结果表明，不分节动物门星虫门、Echiura门和Myzostomida门是环节动物辐射的一部分，但除Echiura门外，它们的环节动物姐妹分类群尚未确定。虽然更多的包容性分类单位（Scolecida，Palpata，Canalpata和Aciculata）已经提出，解决环节动物的关系一直很难使用形态或分子单或多基因数据。因此，环节动物的进化史仍然没有解决，任何关于环节动物进化的结论，就像祖先环节动物的形式一样，无论是穴居还是爬行都是有争议的。这就对使用示范物种作为祖先环节动物状况的代表提出了质疑（例如，Platynereis）。另一方面，两位申请人收集的初步数据表明，使用表达序列Taqs（= EST）库大幅增加每个分类单元的分子数据量会导致分析之间的节点支持和一致性增加。因此，在这个项目中，我们希望解决环节动物的胚胎发育使用的EST文库的基础上的单基因组方法。应使用454测序生成几种环节动物的EST文库。与特定基因的扩增相比，这增加了每个分类单元的序列信息量三到四个数量级。我们希望能有力地解决我们的分类单元采样的环节动物生命树的骨干，从而有助于关于环节动物进化的结论。

Annelida is an ancient and very diverse animal taxon inhabiting diverse habitats from the deep sea to terrestrial soils. Being one of the three animal groups with segmentation, deciphering the evolution of Annelida is crucial to our understanding of the evolution of segmentation. Traditionally, Annelida comprised polychaetes (e.g., lugworms) and clitellates (e.g., earthworms and leeches). While the placement of Clitellata within polychaetes is well supported, their polychaete sistergroup is uncertain. It has been shown that the unsegmented animal “phyla” Sipuncula and Echiura as well as Myzostomida are part of the annelid radiation, but except for Echiura their annelid sistertaxa remain undetermined. Although more inclusive taxonomic units (Scolecida, Palpata, Canalipalpata, and Aciculata) have been put forward, resolving annelid relationships has been difficult using either morphological or molecular single or multiple gene data. Thus, the phylogeny of Annelida is still unresolved and any conclusions about the evolution of Annelida, like the form of the ancestral annelid either as burrowing or as crawling are contentious. This is calling into question the use of exemplar species as representatives of the ancestral annelid condition (e.g., Platynereis). On the other hand, preliminary data gathered by the two applicants show that substantially increasing the amount of molecular data per taxon using expressed sequence taqs (= EST) libraries results in an increase in both nodal support and congruence between analyses. Therefore, in this proposed project we want to resolve the phylogeny of Annelida using a phylogenomic approach based on EST libraries. EST libraries of several annelids shall be generated using 454 sequencing. This increases the amount of sequence information per taxon by three to four orders of a magnitude in comparison to the amplification of specific genes. We expect to robustly resolve the backbone of the annelid tree of life given our taxon sampling and thus to contribute to conclusions regarding the evolution of Annelida.