Molecular phylogenetics of gnathostomous (jawed) fishes: old bones, new cartilage
Molecular phylogenetics of gnathostomous (jawed) fishes: old bones, new cartilage
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DOI：
10.1046/j.1463-6409.2001.00067.x
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发表时间：
2001-10-01
影响因子：
2.5
通讯作者：
Janke, A
中科院分区：
文献类型：
--
作者：
Arnason, U;Gullberg, A;Janke, A
软骨鱼类（软骨鱼类）传统上被认为是有颌脊椎动物的早期分支。为了研究一些关键的软骨鱼类的关系，我们已经测序的线粒体基因组的holocephalan嵌合体monstrosa（鼠鱼）和基底galeomorph物种Heterodontus francisci（角鲨），并分析了它们与相应的数据集的其他几个软骨鱼类，硬骨鱼，腔棘鱼，非洲肺鱼和bichir。树的生根点是使用明确的外群，海七鳃鳗，海文昌鱼或棘皮动物。系统发育分析确定单系软骨鱼类在一个终端的位置在鱼树，贷款不支持传统上接受的基础位置软骨鱼类之间现存的gnathostomes。研究结果表明，软骨特征现存软骨鱼类是胚胎条件的保留，因此代表了衍生的，而不是原始的系统发育和发育阶段。同样，分析表明，开放的鳃缝的新塞拉（鲨鱼和射线）构成了一个派生的状态相比，鳃盖（鳃盖）的特点硬骨鱼和holocephalans。这些分析并不支持所谓的角鲨/盔鲨假说，该假说认为蝙蝠形动物（鲨鱼，鳐）是从最近的鲨目动物（鲨鱼）中产生的。与鱼类和颚口类进化的共同理解不一致的是，有肺的两个分类群，非洲肺鱼和bichir，在鱼类树中处于基础位置。这些发现对各种脊椎动物，特别是鱼类，分支的分类命名法的系统发育有效性提出了质疑。
Cartilaginous fishes (chondrichthyans) have traditionally been taken as an early offshoot among jawed vertebrates. To examine some crucial chondrichthyan relationships, we have sequenced the mitochondrial genomes of the holocephalan Chimaera monstrosa (ratfish) and the basal galeomorph species Heterodontus francisci (horn shark) and analysed them together with the corresponding data set of several other chondrichthyans, teleosts, the coelacanth, the African lungfish and the bichir. The rooting point of the tree was established using unequivocal outgroups, the sea lamprey , the sea lancelet or echinoderms. The phylogenetic analyses identified monophyletic Chondrichthyes in a terminal position in the piscine tree, lending no support to the traditionally accepted basal position of cartilaginous fishes among extant gnathostomes. The findings suggest that the cartilage characterizing extant chondrichthyans is a retention of an embryonic condition, thus representing a derived rather than a primitive phylogenetic and developmental stage. Similarly, the analyses suggest that the open gill slits of neoselachians (sharks and rays) constitute a derived state compared to the operculum (gill cover) characterizing bony fishes and holocephalans. The analyses did not support the so-called Squalea/Galea hypothesis which posits that batomorphs (sharks, rays) have arisen from recent selachians (sharks). Inconsistent with the common understanding of piscine and gnathostome evolution, the two taxa having lungs, the African lungfish and the bichir, had a basal position in the piscine tree. The findings put into question the phylogenetic validity of the taxonomic nomenclature attributed to various vertebrate, notably piscine, clades.