Corliss J O
Department of Zoology, University of Maryland, College Park 20742.
Biosystems. 1988;21(3-4):323-31. doi: 10.1016/0303-2647(88)90029-9.
Although the assumption has long been made that the Ciliophora arose from flagellates, limited progress has been made in determining exactly what extant group - flagellate or other - may best resemble the ancestral "preciliate" assemblage. The distinctiveness of the ciliates and of the many protist phyla containing flagellated stages in their life cycles makes the recognition of potentially homologous features difficult. The suggestion that there may be a phylogenetic relationship between dinoflagellates and ciliates, while seeming unlikely from consideration of a number of specialized characters, is attracting increased attention. This is because some basic similarities (possibly shared derived characters) are characteristic of many species from both groups: cortical alveoli, tubular mitochondrial cristae, kinetidal systems, acentric mitoses with persisting nuclear envelope, functional cytostome, extrusomes (mucocytsts and explosive trichocysts), locomotory organelles, and small subunit rRNAs (close structural similarity values). But many questions remain unanalyzed or unanswered, and caution is still advisable in drawing any firm conclusions about the evolutionary closeness of ciliates and dinoflagellates.
尽管长期以来人们一直认为纤毛虫纲起源于鞭毛虫，但在确定究竟哪个现存类群——鞭毛虫类或其他类群——可能最类似于祖先的“前纤毛虫”组合方面，进展有限。纤毛虫以及许多在生命周期中含有鞭毛阶段的原生生物门的独特性，使得识别潜在的同源特征变得困难。虽然从一些特化特征来看，甲藻和纤毛虫之间可能存在系统发育关系这一观点似乎不太可能，但却越来越受到关注。这是因为两组中的许多物种都具有一些基本相似性（可能是共同的衍生特征）：皮层小泡、管状线粒体嵴、动体系统、具有持续核膜的无中心有丝分裂、功能性胞口、排出体（黏液泡和爆发性刺丝泡）、运动细胞器以及小亚基核糖体RNA（结构相似性值相近）。但许多问题仍未得到分析或解答，在就纤毛虫和甲藻的进化亲缘关系得出任何确凿结论时仍需谨慎。
