A Phylogeny of Major Metazoan Radiations

9807100布朗，韦斯动物线粒体DNA(MtDNA)是一个小的，非染色体的基因组，通常约16kb，包含37个基因。主要动物群体之间的mtDNA比较发现了几个共性：1)除了一些线虫mtDNA，以及其他单一蛋白编码基因(ATP8)外，基因含量是不变的，由37个基因组成。2)基因排列通常在长时间的进化过程中保持不变。3)对特定基因排列的选择很少。4)大量潜在的基因重排使得不同谱系的融合变得不太可能。5)除了少数例外，基因排列在主要群体中似乎是稳定的，但在他们之间是可变的。所有这些特征使得线粒体基因排列的比较成为推断古代系统发育关系的有力手段。从这些比较中，我们已经能够推断出几个更高级别的进化关系，对于这些关系，所有其他类型的数据都是模棱两可的。我们打算确定一种动物的完整线粒体DNA序列和基因安排，这些动物分别代表以下每一个类群：甲壳动物类群Rympedia和Maxillopoda，多足类，五足目，Priapula，Phoronida，Etorecta，腕足类类群关节类和无节类，软体动物类群头足类和Scapopoda，环节动物类类Pogonophora，Sipuncula，Echiura，Nematatoda和Platyhelmints。我们将比较这些分支，以及许多已发表的基因排列，以及比较DNA和推断的氨基酸序列，以推断较高后生动物类群之间的进化关系。

9807100 Brown, Wes Mitochondrial DNA (mtDNA) of animals is a small, extrachromosomal genome typically about 16 kilobases and containing 37 genes. MtDNA comparisons among major animal groups suggest several generalities: 1) With the exception of some cnidarian mtDNAs, and otherwise for a single protein-encoding gene (ATP8), gene content is invariant, consisting of 37 genes. 2) Gene arrangements commonly remain unchanged over long periods of evolutionary time. 3) There is little selection for particular gene arrangements. 4) The great number of potential gene rearrangements makes convergence in different lineages unlikely. 5) With few exceptions, gene arrangements seem stable within major groups, but variable between them. All of these characteristics make the comparison of mitochondrial gene arrangements a powerful means for inferring ancient phylogenetic relationships. From these comparisons we have been able to infer several higher level evolutionary relationships for which all other types of data had been equivocal. We intend to determine the complete mitochondrial DNA sequences and gene arrangements of an animal representing each of the following groups: The crustacean groups Remipedia and Maxillopoda, Myriapoda, Pentastoma, Priapula, Phoronida, Ectoprocta, the brachiopod groups Articulata and Inarticulata, the mollusk groups Cephalopoda and Scaphopoda, the annelid groups Polychaeta and Hirudinea, Pogonophora, Sipuncula, Echiura, Nematoda, and Platyhelminthes. We will compare these cladistically, along with many published gene arrangements, as well as compare DNA and inferred amino acid sequences in order to infer evolutionary relationships among higher metazoan groups.