Phylogenomic analysis of Nereididae (Annelida)

网虫科是一组环节动物蠕虫，在世界各地的海洋、咸水或淡水栖息地都可以找到，已有650多个物种被描述。环节动物在进化发育生物学、生殖生物学和生态学中得到了广泛的研究。杜氏扁平线虫是目前研究得最多的模式生物。该物种已经建立了许多重要的实验室技术，并详细研究了参与胚胎发生、节段形成和再生、神经系统和眼睛发育的基因表达。尽管菊科是被研究得最好的环节动物分类群之一，但这个类群的系统发育到目前为止还没有得到很好的解决。然而，要研究这一重要模式的生活史、基因组和形态进化所依据的步骤，就必须了解其与其近亲的系统发育关系。该项目的主要目标是重建一个得到充分支持的斑潜蝇的系统发育。通过使用杂交靶标浓缩和随后的灯盏花属测序，将对大约65个物种和96个个体(涵盖选定物种的不同地理起源)的大约250个基因座进行系统基因组分析，这些基因座代表海鞘类的多样性。目标浓缩的诱饵将基于在该项目中产生的10个选定近海物种的一组转录本。这一系统发育将被用来检验目前的菊科分类是否与单系群一致。此外，这个系统发育框架将最终提供一个模式环节动物Dumerilii在网虫类中的稳定位置。在这一系统发育的基础上，祖先状态重建将被用来推断蠕虫的繁殖方式、生活方式和栖息地偏好的进化。

Nereididae are a group of annelid worms that can be found worldwide in marine, brackish, or freshwater habitats and more than 650 species have been described. Nereidid annelids have been extensively studied in evolutionary developmental biology, reproductive biology and ecology. The nereidid Platynereis dumerilii became the best investigated model organism of Lophotrochozoa in general. Many important laboratory techniques have been established for this species and gene expression involved in embryogenesis, segment formation and regeneration, development of the nervous system and eyes are studied in detail. Even though nereidids are one of the best investigated annelid taxa, the phylogeny of this group has not been well-resolved so far. However, knowing the phylogenetic relationships of Platynereis dumerilii to its closest relatives is necessary for studying the steps that underlie life history, genomic, and morphological evolution of this important model.The main objective of this project is to reconstruct a well-supported phylogeny for nereidids. By using hybrid target enrichment with subsequent Illumina sequencing, a phylogenomic analysis based on approximately 250 loci derived for around 65 species and 96 individuals (covering different geographic origins for selected species) representing the diversity of nereidids will be conducted. Baits for target enrichment will be based on a set of transcriptomes from 10 selected nereidid species generated within this project. This phylogeny will be used to test if the current classification of nereidids coincides with monophyletic groups. Moreover, this phylogenetic framework will finally provide a stable placement of the model annelid Platynereis dumerilii within nereidids. Based on this phylogeny, ancestral state reconstruction will be used to infer the evolution of reproductive modes, life-style and habitat preference of nereidid worms.