Easteal S
Human Genetics Group, John Curtin School of Medical Research, Australian National University, Canberra ACT.
Genetics. 1990 Jan;124(1):165-73. doi: 10.1093/genetics/124.1.165.
The rates of nucleotide substitution at four genes in four orders of eutherian mammals are compared in relative rate tests using marsupial orthologs for reference. There is no evidence of systematic variation in evolutionary rate among the orders. The sequences are used to reconstruct the phylogeny of the orders using maximum likelihood, parsimony and compatibility methods. A branching order of rodent then ungulate then primate and lagomorph is overwhelmingly indicated. The nodes of the nucleotide based cladograms are widely separated in relation to the total lengths of the branches. The assumption of a star phylogeny that underlies Kimura's test for molecular evolutionary rate variation is shown to be invalid for eutherian mammals. Excess variance in nucleotide or amino acid differences between mammalian orders, above that predicted by neutral theory is explained better by variation in divergence time than by variation in evolutionary rate.
在相对速率测试中,以有袋类直系同源基因作为参考,比较了真兽亚纲四个目哺乳动物中四个基因的核苷酸替换率。没有证据表明这些目之间的进化速率存在系统差异。利用最大似然法、简约法和相容性方法,这些序列被用于重建各目的系统发育。结果强烈表明,分支顺序为啮齿目,然后是有蹄类,接着是灵长目和兔形目。基于核苷酸的分支图的节点相对于分支的总长度相距甚远。木村分子进化速率变异测试所依据的星状系统发育假设被证明对真兽亚纲哺乳动物无效。哺乳动物目之间核苷酸或氨基酸差异的过量方差,超出中性理论预测的部分,用分歧时间的差异比用进化速率的差异能更好地解释。