Phylogenomic analyses unravel annelid evolution
Phylogenomic analyses unravel annelid evolution
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DOI：
10.1038/nature09864
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发表时间：
2011-03-03
期刊：
影响因子：
64.8
通讯作者：
Bleidorn, Christoph
中科院分区：
文献类型：
--
作者：
Struck, Torsten H.;Paul, Christiane;Bleidorn, Christoph
环节动物，即环状蠕虫，是一个高度多样化的动物门，包括超过15,000种已描述的物种，构成了从潮间带到深海的主要底栖大型动物。一个健全的环节动物系统发育将塑造我们对动物身体计划进化的理解，并阐明双边地面模式。传统上，环节动物被分为两大类：cliitellata（蚯蚓和水蛭）和polychaetes（刚毛蠕虫），但最近的证据表明，其他曾经被认为是独立门的分类群（Sipuncula， Echiura和Siboglinidae（也称为Pogonophora））应该包括在环节动物中（1-4）。然而，我们对环节动物的深层进化关系仍然知之甚少，需要对环节动物的进化史进行有力的重建。在这里，我们展示了34个环节动物分类群的系统基因组分析，使用了47,953个氨基酸位置，恢复了一个很好的支持系统发育的主要分裂。我们的研究结果恢复了该树基部的毛翼类、粘孔类和绢孔类，尽管粘孔类的位置由于其长枝而仍然不确定。剩下的分类群分为两个分支：Errantia（包括模式环节动物Platynereis）和Sedentaria（包括cliitellata）。祖先的特征重建表明，这些进化支表现出对错误或久坐生活方式的适应，伴随着蠕动运动、旁足和感觉知觉等形态特征的改变。最后，环节动物的生活史特征似乎是系统发育上的信息。
Annelida, the ringed worms, is a highly diverse animal phylum that includes more than 15,000 described species and constitutes the dominant benthic macrofauna from the intertidal zone down to the deep sea. A robust annelid phylogeny would shape our understanding of animal body-plan evolution and shed light on the bilaterian ground pattern. Traditionally, Annelida has been split into two major groups: Clitellata (earthworms and leeches) and polychaetes (bristle worms), but recent evidence suggests that other taxa that were once considered to be separate phyla (Sipuncula, Echiura and Siboglinidae (also known as Pogonophora)) should be included in Annelida(1-4). However, the deep-level evolutionary relationships of Annelida are still poorly understood, and a robust reconstruction of annelid evolutionary history is needed. Here we show that phylogenomic analyses of 34 annelid taxa, using 47,953 amino acid positions, recovered a well-supported phylogeny with strong support for major splits. Our results recover chaetopterids, myzostomids and sipunculids in the basal part of the tree, although the position of Myzostomida remains uncertain owing to its long branch. The remaining taxa are split into two clades: Errantia (which includes the model annelid Platynereis), and Sedentaria (which includes Clitellata). Ancestral character trait reconstructions indicate that these clades show adaptation to either an errant or a sedentary lifestyle, with alteration of accompanying morphological traits such as peristaltic movement, parapodia and sensory perception. Finally, life history characters in Annelida seem to be phylogenetically informative.