A multi-locus analysis of phylogenetic relationships within cheilostome bryozoans supports multiple origins of ascophoran frontal shields
A multi-locus analysis of phylogenetic relationships within cheilostome bryozoans supports multiple origins of ascophoran frontal shields
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DOI：
10.1016/j.ympev.2011.07.005
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发表时间：
2011-11-01
影响因子：
4.1
通讯作者：
Lavery, Shane D.
中科院分区：
文献类型：
--
作者：
Knight, Sarah;Gordon, Dennis P.;Lavery, Shane D.
苔藓虫目的系统发育关系目前还不确定，提出了许多形态假说，但很少用独立的分子分析手段进行验证。这项研究使用了91种唇口苔藓虫(34种新测序)的线粒体和核起源的5个基因座的DNA序列数据。这极大地提高了分类覆盖率和该目分子分析中使用的基因座数量，并使人们能够更深入地了解切口目的进化史。对单个基因座进行了最大似然和贝叶斯分析，同时采用了分区多基因座方法，以及基于形态假设的一系列拓扑测试。综上所述，这些都提供了一套完整的唇形目的系统发育分析。根据这些结果，对该目的进化史进行了推断，并根据从分子数据获得的独立证据讨论了提出的形态假说。亚目天牛目被证明是非单系的，并且Ascus及其相关结构似乎有多个起源，涉及到层序的扩展。这进一步得到了由额盾形态所定义的四个阿司匹林等级(棘骨形态/棘晶、海马形态/裸囊、丘状/鞭状、麻风/麻风)中每一级内缺乏单性的支持。Chorizopora在系统发育上与Hippothohaidae不同，为裸囊体额屏蔽型的多重起源提供了强有力的证据。进一步的证据支持的形态假说，麻风前盾的多个尺骨来源，使用一套逐步的拓扑假设检验和多位点系统发育检查相结合。(C)2011 Elsevier Inc.保留所有权利。
Phylogenetic relationships within the bryozoan order Cheilostomata are currently uncertain, with many morphological hypotheses proposed but scarcely tested by independent means of molecular analysis. This research uses DNA sequence data across five loci of both mitochondrial and nuclear origin from 91 species of cheilostome Bryozoa (34 species newly sequenced). This vastly improved the taxonomic coverage and number of loci used in a molecular analysis of this order and allowed a more in-depth look into the evolutionary history of Cheilostomata. Maximum likelihood and Bayesian analyses of individual loci were carried out along with a partitioned multi-locus approach, plus a range of topology tests based on morphological hypotheses. Together, these provide a comprehensive set of phylogenetic analyses of the order Cheilostomata. From these results inferences are made about the evolutionary history of this order and proposed morphological hypotheses are discussed in light of the independent evidence gained from the molecular data.Infraorder Ascophorina was demonstrated to be non-monophyletic, and there appears to be multiple origins of the ascus and associated structures involved in lophophore extension. This was further supported by the lack of monophyly within each of the four ascophoran grades (acanthostegomorph/spinocystal, hippothoomorph/gymnocystal, umbonulomorph/umbonuloid, lepraliomorph/lepralioid) defined by frontal-shield morphology. Chorizopora, currently classified in the ascophoran grade Hippothoomorpha, is phylogenetically distinct from Hippothoidae, providing strong evidence for multiple origins of the gymnocystal frontal shield type. Further evidence is produced to support the morphological hypothesis of multiple umbonuloid origins of lepralioid frontal shields, using a step-wise set of topological hypothesis tests combined with examination of multi-locus phylogenies. (C) 2011 Elsevier Inc. All rights reserved.