Phylogenomics of myzostomids and annelids - causes and consequences of incongruence in phylogenetic analyses

然而基于单个或几个基因的分子系统发育经常导致明显的相互矛盾的信号，系统基因组学的使用被认为克服了这些问题，并且“结束不一致”在即。尽管有这些希望，随后使用系统基因组数据集对后生动物系统发育进行的分析在树的许多部分仍然存在分歧。标记间不一致的原因可能是生物学的，也可能是方法学的。以myzostomids为例，研究表明，属于不同功能类或大分子复合物的基因支持关于该类群系统发育起源的不同假设。然而，由于缺乏数据，尚无法在严格的统计框架内分析这一现象。该项目旨在利用454测序技术对网状Myzostoma cirriferum转录子进行测序。通过对这些数据的分析，我们建议研究基因的功能类别在系统发育重建中的作用。此外，计划进行模拟研究，以调查不一致信号对分析串联数据集的影响。最后，设想建立一个很好的支持的环节动物和相关的光虫类群的系统发育，特别强调粘孔虫。

Whereas molecular phylogenies based on single or a few genes often lead to apparently conflicting signals, the use of phylogenomics was thought to overcome these problems, and “ending incongruence” was in sight. Despite these hopes, subsequent analysis of metazoan phylogeny using phylogenomic datasets still disagree in many parts of the tree. Reasons for incongruence between markers might be either biological or methodological. Using myzostomids as an example, it has been shown that genes belonging to different functional classes or macromolecular complexes support different hypothesis regarding the phylogenetic origin of this group. However, due to lack of data, analysing this phenomenon in a rigorous statistical framework was not possible yet. The proposed project aims to sequence the Myzostoma cirriferum transcriptom using 454-sequencing techniques. Analysing this data, it is proposed to investigate the role of functional classes of genes on phylogeny reconstruction. Moreover, it is planned to conduct simulation studies to investigate the impact of incongruent signal on analysing concatenated datasets. Finally, it is envisaged to establish a well supported phylogeny of annelid and related lophotrochozoan taxa with special emphasis placed on the Myzostomida.