First molecular estimate of cyclostome bryozoan phylogeny confirms extensive homoplasy among skeletal characters used in traditional taxonomy
First molecular estimate of cyclostome bryozoan phylogeny confirms extensive homoplasy among skeletal characters used in traditional taxonomy
复制标题
DOI：
10.1016/j.ympev.2009.02.002
复制
发表时间：
2009-07-01
影响因子：
4.1
通讯作者：
Taylor, Paul D.
中科院分区：
文献类型：
--
作者：
Waeschenbach, Andrea;Cox, Cymon J.;Taylor, Paul D.
环口虫是窄口虫纲现存的唯一代表，窄口虫纲是一种古老的海洋苔藓动物。先前对环状苔藓虫的分支分析，完全基于骨骼特征，揭示了形态特征之间广泛的同源性。本研究首次提出了环口虫的分子系统发育，并证实了以往的同源性发现。对22个环状苔藓虫类群以及外类群（Pectinatella magnifica和Flustrellidra hispida）几乎完整的Isr和ssrDNA片段进行了测序。他们发现了三个得到充分支持的主要分支，但它们之间的关系尚不清楚。管状孢子亚目是多系的，在所有三个主要分支中都有代表。微管卟啉类斜尾虫科被分解为多系；Plagioecia与Lichenoporidae和Densiporidae归为一类，entalopholecia、Diplosolen和Cardioecia则组成了一个包括Frondiporidae和Horneridae的副葡萄亚群。Cerioporina亚目也具有多系性；密孢子虫科与斜孢子虫科和地衣孢子虫科同属一组，而异孢子虫科与细孢子虫科同属一组。不可能明确地归类于棘虫科。形态学特征映射是为了找到支持主要分支相互关系的三种可能假设之一的证据而进行的，但结果是模糊的。本研究质疑形态特征在多大程度上可以用于环孔苔藓虫的系统发育研究，无论是化石还是现存的，以及它们的形态在多大程度上是生态表型可塑性和趋同进化的结果。许多非单系分类群的发现对灭绝率评估和使用化石环口来校准分子树具有重要意义。(C) 2009爱思唯尔公司版权所有。
The Cyclostomata are the only extant representatives of the class Stenolaemata, an ancient group of exclusively marine bryozoans. Previous cladistic analyses of cyclostome bryozoans, based exclusively on skeletal characters, revealed extensive homoplasy amongst morphological traits. This study presents the first molecular phylogeny for Cyclostomata and confirms the previous findings of homoplasy. Almost complete Isr and ssrDNA fragments were sequenced for 22 taxa of cyclostome bryozoans, plus the out-group (Pectinatella magnifica and Flustrellidra hispida). Three well-supported major clades were found, but their inter relationships are unclear. Suborder Tubuliporina was polyphyletic, with representatives found in all three major clades. The tubuliporine family Plagioeciidae was resolved as polyphyletic; Plagioecia grouped with Lichenoporidae and Densiporidae, whereas Entalophoroecia, Diplosolen and Cardioecia formed a paraphyletic subgroup that included Frondiporidae and Horneridae. The suborder Cerioporina was also polyphyletic; Densiporidae grouped with Plagioecia and Lichenoporidae, whereas Heteroporidae nested in a paraphyletic subgroup of tubuliporines, with the Crisiidae forming the sister-group to this clade. Cinctiporidae could not be placed unambiguously. Morphological character mapping was performed in order to find evidence favouring one of the three possible hypotheses of inter relationships of the major clades, but the results were ambiguous. This study questions the extent to which morphological characters can be used in phylogenetic studies of cyclostome bryozoans, both fossil and extant, and how far their morphology is the result of ecophenotypic plasticity and convergent evolution. The finding of numerous non-monophyletic taxa has implications for extinction rate assessment and for the use of fossil cyclostomes to calibrate molecular trees. (C) 2009 Elsevier Inc. All rights reserved.