A time-calibrated molecular phylogeny of the precious corals: reconciling discrepancies in the taxonomic classification and insights into their evolutionary history.
A time-calibrated molecular phylogeny of the precious corals: reconciling discrepancies in the taxonomic classification and insights into their evolutionary history.
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DOI：
10.1186/1471-2148-12-246
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发表时间：
2012-12-18
影响因子：
3.4
通讯作者：
Sánchez JA
中科院分区：
文献类型：
--
作者：
Ardila NE;Giribet G;Sánchez JA
与海山相关的动物群通常被认为是高度特有的，但导致这种特有现象的隔离和多样化过程在这些深度的记录很少。同样，由于难以获取样本，深海生物的物种界定和系统发育研究仍然很少，有时甚至存在争议。珍贵的珊瑚科 Coralliidae 内的系统发育关系在很大程度上仍未得到探索，其两个组成属（居维叶珊瑚属和副珊瑚属拜耳和凯恩斯属）的单系性尚未得到解决。传统上认为，不同物种之间的群体形式的多样性与其支撑轴形状的多样性相关，但这些特征的系统发育意义仍有待检验。因此，我们使用线粒体序列数据来评估珊瑚属和副珊瑚属的单系性以及该科中几乎所有命名类群的物种边界。对来自整个珊瑚科动物范围的物种进行了检查，包括来自南极洲、夏威夷、日本、新西兰、台湾、塔斯马尼亚、东太平洋和西大西洋的材料。对五个线粒体区域（COI、16S rRNA、ND2 和 ND3-ND6）的串联分析恢复了两个主要的珊瑚分支。一个进化枝由两个亚群组成，第一个亚群包括该属的模式种红珊瑚，以及一小群副珊瑚物种（P. japonicum 和 P. tortuosum）和 C. medea（进化枝 I-A）；另一个亚群包括六个珊瑚物种的分辨率较差的组合（C. abyssale、C. ducale、C. Imperiale、C. laauense、C. niobe 和 C. sulcatum；进化枝 I-B）。第二个主要进化枝已得到很好的解析，包括珊瑚和副珊瑚物种（C. elatius、C. kishinouyei、C. konojoi、C. niveum、C. secundum、Corallium sp.、Pararallium nix、Paracorallium thrinax 和 Paracorallium spp.）。对该分支的传统分类学研究描绘了 11 个形态种，这些形态种与一般混合圣诞聚结 (GMYC) 模型一致。多位点物种树方法还鉴定了相同的两个得到良好支持的进化枝，进化枝 I-B 在物种树 (18.0-15.9 mya) 中比在基因树 (35.2-15.9 mya) 中更新。相比之下，进化枝 II 的多样化时间在物种树 (136.4-41.7 mya) 中比在基因树 (66.3-16.9 mya) 中更古老。我们的结果没有为珊瑚科中目前公认的两个属的分类地位提供支持。鉴于副珊瑚属物种都嵌套在珊瑚属内，我们认识到珊瑚科珊瑚属珊瑚，其中包括该科的模式种，因此认为副珊瑚属是珊瑚属的初级同义词。我们建议使用 Hemicorallium Grey 属作为 I-B 进化枝（具有长杆状骨片、圆柱形自体动物和光滑轴的物种）。进化枝 I-B 中的物种界定仍不清楚，两个主要进化枝中珊瑚科物种的分子分辨率不一致。一些物种具有广泛的分布、最近的多样化时间和较低的线粒体DNA分歧，而其他物种则表现出较窄的异域分布、较早的多样化时间和较高水平的线粒体DNA分辨率。
Seamount-associated faunas are often considered highly endemic but isolation and diversification processes leading to such endemism have been poorly documented at those depths. Likewise, species delimitation and phylogenetic studies in deep-sea organisms remain scarce, due to the difficulty in obtaining samples, and sometimes controversial. The phylogenetic relationships within the precious coral family Coralliidae remain largely unexplored and the monophyly of its two constituent genera, Corallium Cuvier and Paracorallium Bayer & Cairns, has not been resolved. As traditionally recognized, the diversity of colonial forms among the various species correlates with the diversity in shape of their supporting axis, but the phylogenetic significance of these characters remains to be tested. We thus used mitochondrial sequence data to evaluate the monophyly of Corallium and Paracorallium and the species boundaries for nearly all named taxa in the family. Species from across the coralliid range, including material from Antarctica, Hawaii, Japan, New Zealand, Taiwan, Tasmania, the eastern Pacific and the western Atlantic were examined. The concatenated analysis of five mitochondrial regions (COI, 16S rRNA, ND2, and ND3-ND6) recovered two major coralliid clades. One clade is composed of two subgroups, the first including Corallium rubrum, the type species of the genus, together with a small group of Paracorallium species (P. japonicum and P. tortuosum) and C. medea (clade I-A); the other subgroup includes a poorly-resolved assemblage of six Corallium species (C. abyssale, C. ducale, C. imperiale, C. laauense, C. niobe, and C. sulcatum; clade I-B). The second major clade is well resolved and includes species of Corallium and Paracorallium (C. elatius, C. kishinouyei, C. konojoi, C. niveum, C. secundum, Corallium sp., Paracorallium nix, Paracorallium thrinax and Paracorallium spp.). A traditional taxonomic study of this clade delineated 11 morphospecies that were congruent with the general mixed Yule-coalescent (GMYC) model. A multilocus species-tree approach also identified the same two well-supported clades, being Clade I-B more recent in the species tree (18.0-15.9 mya) than in the gene tree (35.2-15.9 mya). In contrast, the diversification times for Clade II were more ancient in the species tree (136.4-41.7 mya) than in the gene tree (66.3-16.9 mya). Our results provide no support for the taxonomic status of the two currently recognized genera in the family Coralliidae. Given that Paracorallium species were all nested within Corallium, we recognize the coralliid genus Corallium, which includes the type species of the family, and thus consider Paracorallium a junior synonym of Corallium. We propose the use of the genus Hemicorallium Gray for clade I-B (species with long rod sclerites, cylindrical autozooids and smooth axis). Species delimitation in clade I-B remains unclear and the molecular resolution for Coralliidae species is inconsistent in the two main clades. Some species have wide distributions, recent diversification times and low mtDNA divergence whereas other species exhibit narrower allopatric distributions, older diversification times and greater levels of mtDNA resolution.
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