Dissertation Research: Molecular Systematic Studies of the Placement of Carnivora Within Eutherian Mammals

本研究拟考察食肉目以及其他几个类群在现存的18目真兽哺乳动物中的位置。DNA序列数据将从四个不同的基因座收集：细胞色素B、泛素、组蛋白H3和致癌基因K-ras。使用来自几个不同基因座的核苷酸序列数据，而不是一个大基因的所有序列，可以比较密码子偏差、进化速度和基因间系统发育信号的保留，同时避免任何一个基因座的进化特性。每个目将由至少两个分类群代表，这些分类群将根据先前的系统分析选择尽可能多样化。将采用一种简约的方法结合降低饱和位点的权重来分析数据。此外，分子信息将在单独的分析中与相关的形态学数据相结合。系统发育取样、多基因座的使用和全信息分析相结合，使迄今为止关于许多哺乳动物目之间关系的模棱两可的信息有可能得到更好的理解，并使目前的哺乳动物分子进化理论得到更好的检验和扩展。

This study proposes to examine the placement of the order Carnivora as well as several other groups, among the eighteen extant orders of eutherian mammals. DNA sequence data will be gathered from four different loci: Cytochrome B, Ubiquitin, Histone H3, and the oncogene K-ras. The use of nucleotide sequence data from several different loci, rather than all the sequence of one large gene, yields comparisons of codon bias, rate of evolution, and retention of phylogenetic signal between genes as well as avoiding the evolutionary, peculiarities of any one locus. Each order will be represented by at least two taxa, which will be chosen to be as diverse as possible based on prior systematic analyses. A parsimony approach combined with down- weighting of saturated sites will be used to analyze the data. Additionally, molecular information will be combined with the pertinent morphological data in a separate analysis. This combination of phylogenetic sampling, use of multiple loci, and total information analysis makes it likely that the so far equivocal information on relationships of many of the mammalian orders will be better understood and that current theories of mammalian molecular evolution will be better tested and expanded.