DeSalle Rob, Schierwater Bernd
American Museum of Natural History, New York, Sackler Institute for Comparative Genomics, New York, NY 10024, USA.
Bioessays. 2008 Nov;30(11-12):1043-7. doi: 10.1002/bies.20842.
Metazoa are one of the great monophyletic groups of organisms. They comprise several major groups of organisms readily recognizable based on their anatomy. These major groups include the Bilateria (animals with bilateral symmetry), Cnidaria (jellyfish, corals and other closely related animals), Porifera (sponges), Ctenophores (comb jellies) and a phylum currently made up of a single species, the Placozoa. Attempts to systematize the relationships of these major groups as well as to determine relationships within the groups have been made for nearly two centuries. Many of the attempts have led to frustration, because of a lack of resolution between and within groups. Other attempts have led to "a new animal phylogeny". Now, a study by Dunn et al., using the expresssed sequence tag (EST) approach to obtaining high-throughput large phylogenetic matrices, presents an "even newer" animal phylogeny. There are two major aspects of this study that should be of interest to the general biological community. First, the methods used by the authors to generate their phylogenetic hypotheses call for close examination. Second, the relationships of animal taxa in their resultant trees also prompt further discussion.
后生动物是生物界中一个重要的单系类群。它们包括几个主要的生物类群，根据其解剖结构很容易识别。这些主要类群包括两侧对称动物（具有两侧对称的动物）、刺胞动物门（水母、珊瑚及其他亲缘关系密切的动物）、多孔动物门（海绵）、栉水母动物门（栉水母）以及目前仅由一个物种组成的扁盘动物门。近两个世纪以来，人们一直试图梳理这些主要类群之间的关系，并确定各主要类群内部的关系。由于类群之间和类群内部缺乏分辨率，许多尝试都以失败告终。其他尝试则产生了“一种新的动物系统发育树”。现在，邓恩等人的一项研究采用表达序列标签（EST）方法来获取高通量的大型系统发育矩阵，提出了“一个更新的”动物系统发育树。这项研究有两个主要方面应该会引起广大生物学界的兴趣。第一，作者用于生成其系统发育假说的方法需要仔细审视。第二，他们所得出的树状图中动物类群之间的关系也引发了进一步的讨论。
