Evolutionary relationships among the eukaryotic crown taxa taking into account site-to-site rate variation in 18S rRNA
Evolutionary relationships among the eukaryotic crown taxa taking into account site-to-site rate variation in 18S rRNA
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DOI：
10.1007/pl00006266
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发表时间：
1997-12-01
影响因子：
3.9
通讯作者：
De Wachter, R
中科院分区：
文献类型：
--
作者：
Van de Peer, Y;De Wachter, R
在这项研究中，我们构建了一棵由500个小亚基核糖体RNA序列组成的自举距离树，这些序列来自属于所谓的真核生物进化之冠的生物。考虑到rRNA序列比对的单个核苷酸的替换率，我们的结果表明：(1)动物、真真菌和脊椎动物有一个共同的起源：连接这些分类群的分支被Bootstrap分析高度支持(Bootstrap Support[BS]1.90%)，(2)稻膜虫和泡虫是姐妹群(BS=75%)，(3)在肺泡内，甲鞭毛虫和蜂形复合体共享共同的祖先BS>；95%，而它们又都与纤毛虫有共同的起源(BS>；在稻草纲中，异形藻、丝孢子菌和卵菌形成一个单系群(BS>；85%)，在此之前有迷路菌和双孢子菌的连续分化。另一方面，根据18S rRNA，许多冠类之间的进化关系仍然不清楚。动物-真菌-鞭毛虫分支与氯离子、泡虫和稻草藻、红藻和几个较小生物群之间的分枝顺序在很大程度上仍未解决。当不考虑站点间速率差异时，推断的树形拓扑低于考虑18S rRNA替换率谱的树形拓扑。这主要表现为快速进化序列的错误分支。此外，当不考虑不同地点之间的不同替换率时，这些动物在大多数距离树上不再表现为单系类群。
In this study we constructed a bootstrapped distance tree of 500 small subunit ribosomal RNA sequences from organisms belonging to the so-called crown of eukaryote evolution. Taking into account the substitution rate of the individual nucleotides of the rRNA sequence alignment, our results suggest that (1) animals, true fungi, and choanoflagellates share a common origin: The branch joining these taxa is highly supported by bootstrap analysis (bootstrap support [BS] 1 90%), (2) stramenopiles and alveolates are sister groups (BS = 75%), (3) within the alveolates, dinoflagellates and apicomplexans share a common ancestor BS > 95%), while in turn they both share a common origin with the ciliates (BS > 80%), and (4) within the stramenopiles, heterokont algae, hyphochytriomycetes, and oomycetes form a monophyletic grouping well supported by bootstrap analysis (BS > 85%), preceded by the well-supported successive divergence of labyrinthulomycetes and bicosoecids.On the other hand, many evolutionary relationships between crown taxa are still obscure on the basis of 18S rRNA. The branching order between the animal-fungal-choanoflagellates clade and the chlorobionts, the alveolates and stramenopiles, red algae, and several smaller groups of organisms remains largely unresolved.When among-site rate variation is not considered, the inferred tree topologies are inferior to those where the substitution rate spectrum for the 18S rRNA is taken into account. This is primarily indicated by the erroneous branching of fast-evolving sequences. Moreover, when different substitution rates among sites are not considered, the animals no longer appear as a monophyletic grouping in most distance trees.