Reassessment of homology of morphological characters in tetractinellid sponges based on molecular data
Reassessment of homology of morphological characters in tetractinellid sponges based on molecular data
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DOI：
10.1080/106351598260761
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发表时间：
1998-09-01
影响因子：
6.5
通讯作者：
Tillier, S
中科院分区：
文献类型：
--
作者：
Chombard, C;Boury-Esnault, N;Tillier, S
在海绵动物中，就像在其他组织简单的分类群中一样，形态特征的评价和使用是困难的。从28 S rRNA基因5'端开始的前850个核苷酸的系统发育分析在此用于评估用于Tetractinellida亚类分类的骨针的同源性。得到了一棵支持度很好的MP树。研究的9种Tetractinellida的单系证实了tetraxon megasclere作为Tetractinellida的形态突触。两个物种被重新分配，Penares helleri作为Geodiidae，现在被认为已经失去了sterraster microscleres，和Stryphnus mucronatus到Streptosclerophorida。扫描电子显微镜观察到的马钱子微石细胞的形态与链石细胞同源的假说相一致，证实了这种重新分配。另外两个联会形态被证实在tetractinellid分支，同时存在的tetraxon megasclere和aster-type microsclere（Astrophorida）和链巩膜的损失和持续的euaster s.s.微石藻（真星藻目），通过重新分配的Stryphnus mucronatus证明。链索菌微球不能在同源性方面进行评估，因为链索菌可能是并系的（尽管这些节点不支持可靠的bootstrap比例），与目前公认的分类相反。
In sponges, as in other taxa with simple organization, the evaluation and use of morphological characters is difficult. Phylogenetic analysis of the first 850 nucleotides from the 5' end of the 28S rRNA gene is used here to assess the homology of spicules used in the classification of the subclass Tetractinellida. A single well-supported MP tree was obtained. The monophyly of the nine Tetractinellida species studied confirms the tetraxon megasclere as a morphological synapomorphy for the Tetractinellida. Two species are reallocated, Penares helleri as a Geodiidae, now thought to have lost sterraster microscleres, and Stryphnus mucronatus to the Streptosclerophorida. SEM micrographs of Stryphnus microscleres show that the morphology of the sanidasters is Compatible with the hypothesis that they are homologous with streptoscleres and confirm this reallocation. Two other synapomorphies are confirmed within the tetractinellid clade, the simultaneous presence of tetraxon megasclere and aster-type microsclere (Astrophorida) and the loss of the streptosclere and persistence of the euaster s.s. microscleres (Euastrophorida) evidenced by the reallocation of Stryphnus mucronatus. The streptosclere microscleres cannot be evaluated in terms of homology because Streptosclerophorida may be paraphyletic (although these nodes are not supported by reliable bootstrap proportions) contrary to the currently accepted classification.