Dissertation Research: Arthropod Phylogeny Based on Gene Arrangement and Other Characters from Mitochondrial DNA

布朗和拉夫罗夫9972712节肢动物门是动物界(后生动物)中最特殊的，也是最具形态多样性的。虽然它也是研究得最好的物种之一，但它的系统发育地位、单系以及主要谱系之间和内部的关系在很大程度上仍然没有解决。节肢动物在寒武纪大爆发期间最初的快速辐射之后是5亿多年的并行进化，通常是在相似的环境中；这使得根据形态特征或DNA序列比较来理清节肢动物之间的关系即使不是不可能，也是非常困难的。然而，如果我们要解释而不是简单地描述形态和发育数据，如果我们要理解导致有机多样性的过程，了解这些关系是必不可少的。本论文的目的是通过将线粒体DNA上基因的相对排列这一复杂的分子特征与DNA和氨基酸序列比较相结合，来解决一些节肢动物的关系。我们打算从节肢动物和一些相关门的13个主要谱系的代表中确定完整的线粒体DNA序列和基因排列，并将它们与之前发表的10个完整的节肢动物mtDNA进行比较。线粒体基因排列的比较已被证明是推断古代系统发育关系的有力手段，而DNA和氨基酸序列比较可能会在较新的分歧群体分享相同的基因排列时增加分辨率。这项研究还将探讨线粒体DNA进化的动力学，增加我们对线粒体基因组重排的性质和限制的了解。

Brown and Lavrov 9972712The phylum Arthropoda is the most speciose and arguably the most morphologically diverse within the Animal Kingdom (Metazoa). While it is also one of the best studied, its phylogenetic position, monophyly and the relationships among and within its major lineages are still largely unresolved. The initial rapid radiation of arthropods during the "Cambrian explosion" was followed by more than 500 million years of parallel evolution, often in similar environments; this makes it very difficult if not impossible to untangle arthropod relationships based on morphological characters or on DNA sequence comparisons. However, understanding these relationships is essential if we are to interpret rather than simply describe the morphological and developmental data, and if we are to understand the processes leading to organic diversity. The aim of this dissertation project is to resolve some of the arthropod relationships by combining a complex molecular character, the relative arrangement of genes on mitochondrial DNA (mtDNA) with DNA and amino acid sequence comparisons. We intend to determine complete mitochondrial DNA sequences and gene arrangements from 13 representatives of major lineages of arthropods and some related phyla and to compare them along with 10 previously published complete arthropod mtDNAs. The comparison of mitochondrial gene arrangements has been demonstrated to be a powerful means for inferring ancient phylogenetic relationships, while DNA and amino acid sequence comparisons may add resolution when more recently diverged groups share an identical gene arrangement. This study will also address the dynamics of mtDNA evolution, adding to our knowledge of the nature of and constraints on mitochondrial genome rearrangements.