Department of Natural History Science, Graduate School of Science, Hokkaido University, N10 W8, Sapporo 060-0810, Japan.
Mol Phylogenet Evol. 2013 May;67(2):303-10. doi: 10.1016/j.ympev.2013.02.016. Epub 2013 Feb 27.
We reconstructed kinorhynch phylogeny using maximum-likelihood and Bayesian analyses of nuclear 18S and 28S rRNA gene sequences from 30 species in 13 genera (18S) and 23 species in 12 genera (28S), representing eight families and both orders (Cyclorhagida and Homalorhagida) currently recognized in the phylum. We analyzed the two genes individually (18S and 28S datasets) and in combination (18S+28S dataset). We detected four main clades (I-IV). Clade I consisted of family Echinoderidae. Clade II contained representatives of Zelinkaderidae, Antygomonidae, Semnoderidae, Centroderes, and Condyloderes, the latter two currently classified in Centroderidae; within Clade II, Zelinkaderidae, Antygomonidae, and Semnoderidae comprised a clade with strong nodal support. Clade III contained only two species in Campyloderes, also currently classified in the Centroderidae, indicating polyphyly for this family. Clades I-III, containing all representatives of Cyclorhagida included in the analysis except for Dracoderes abei, formed a clade with high nodal support in the 28S and 18S+28S trees. Clade IV, resolved in the 18S and 18S+28S trees with high nodal support, contained only species in order Homalorhagida, with the exception of the cyclorhagid Dracoderes abei. Order Cyclorhagida as it currently stands is thus polyphyletic, and order Homalorhagida paraphyletic. Our results indicate that Dracoderidae has been misplaced in Cyclorhagida based on homoplasious characters. Our analyses did not resolve the relationships among Clades I-III within Cyclorhagida. Neither gene alone nor the combined dataset resolved all nodes in trees, indicating that additional markers will be needed to reconstruct kinorhynch phylogeny.
我们使用最大似然法和贝叶斯分析，对来自 13 属的 30 种（18S）和 12 属的 23 种（28S）的核 18S 和 28S rRNA 基因序列进行了kinorhynch 系统发育重建，这些物种代表了目前在门中认可的两个目（Cyclorhagida 和 Homalorhagida）的 8 个科。我们分别分析了这两个基因（18S 和 28S 数据集）和合并分析（18S+28S 数据集）。我们检测到四个主要分支（I-IV）。分支 I 由 Echinoderidae 科组成。分支 II 包含 Zelinkaderidae、Antygomonidae、Semnoderidae、Centroderes 和 Condyloderes 的代表，后两者目前被归类为 Centroderidae；在分支 II 中，Zelinkaderidae、Antygomonidae 和 Semnoderidae 组成了一个具有强烈节点支持的分支。分支 III 仅包含 Campyloderes 中的两个物种，也目前被归类为 Centroderidae，表明该科为多系起源。包含除 Dracoderes abei 以外的所有分析中 Cyclorhagida 代表的分支 I-III，在 28S 和 18S+28S 树中形成了一个具有高节点支持的分支。分支 IV 在 18S 和 18S+28S 树中以高节点支持的方式解决，仅包含 Homalorhagida 目中的物种，除了 cyclorhagid Dracoderes abei 以外。因此，目前的 Cyclorhagida 目是多系起源的，而 Homalorhagida 目是并系起源的。我们的结果表明，基于同形特征，Dracoderidae 在 Cyclorhagida 中的位置不正确。我们的分析没有解决 Cyclorhagida 内的 I-III 分支之间的关系。单独的基因或组合数据集都没有解决树中的所有节点，这表明需要额外的标记来重建 kinorhynch 系统发育。
