Phylogenomic analyses support traditional relationships within Cnidaria

Cnidaria, the sister group to Bilateria, is the most diverse group of animals in terms of morphology, lifecycles, ecology, and development. How this diversity originated and evolved is not well understood because phylogenetic relationships among major cnidarian lineages are unclear, and recent studies present contrasting phylogenetic hypotheses. Here, we use transcriptome data from 15 newly-sequenced species in combination with 26 publicly available genomes and transcriptomes to assess phylogenetic relationships among major cnidarian lineages. Phylogenetic analyses using different partition schemes and models of molecular evolution, as well as topology tests for alternative phylogenetic relationships, support the monophyly of Medusozoa, Anthozoa, Octocorallia, Hydrozoa, and a clade consisting of Staurozoa, Cubozoa, and Scyphozoa. Support for the monophyly of Hexacorallia is weak due to the equivocal position of Ceriantharia. Taken together, these results further resolve deep cnidarian r...刺胞动物门（Cnidaria）是两侧对称动物（Bilateria）的姊妹群，在形态学、生活史、生态学与发育生物学层面，是物种多样性最为丰富的动物类群。目前学界对其多样性的起源与演化机制尚未形成充分认知，究其原因，主要刺胞动物类群间的系统发育关系仍不明确，且近期相关研究提出了相互矛盾的系统发育假说。本研究整合15个新测序物种的转录组（transcriptome）数据，结合26个公开可用的基因组与转录组数据，对主要刺胞动物类群的系统发育关系展开评估。研究采用多种分区方案（partition schemes）与分子进化模型（models of molecular evolution）开展系统发育分析（phylogenetic analyses），并针对不同系统发育假说进行拓扑结构检验（topology tests），结果支持水母亚门（Medusozoa）、珊瑚虫纲（Anthozoa）、八放珊瑚亚纲（Octocorallia）、水螅虫纲（Hydrozoa），以及由十字水母纲（Staurozoa）、立方水母纲（Cubozoa）与钵水母纲（Scyphozoa）构成的演化支均为单系群（monophyly）。由于角海葵目（Ceriantharia）的系统发育位置存在歧义，六放珊瑚亚纲（Hexacorallia）的单系性支持度较弱。综上，本研究结果进一步厘清了刺胞动物的深层系统发育关系……