Gaut B S, Muse S V, Clark W D, Clegg M T
Department of Botany and Plant Sciences, University of California, Riverside 92521.
J Mol Evol. 1992 Oct;35(4):292-303. doi: 10.1007/BF00161167.
We subjected 35 rbcL nucleotide sequences from monocotyledonous taxa to maximum likelihood relative rate tests and estimated relative differences in rates of nucleotide substitution between groups of sequences without relying on knowledge of divergence times between taxa. Rate tests revealed that there is a hierarchy of substitution rate at the rbcL locus within the monocots. Among the taxa analyzed the grasses have the most rapid substitution rate; they are followed in rate by the Orchidales, the Liliales, the Bromeliales, and the Arecales. The overall substitution rate for the rbcL locus of grasses is over 5 times the substitution rate in the rbcL of the palms. The substitution rate at the third codon positions in the rbcL of the grasses is over 8 times the third position rate in the palms. The pattern of rate variation is consistent with the generation-time-effect hypothesis. Heterogenous rates of substitution have important implications for phylogenetic reconstruction.
我们对来自单子叶植物类群的35个rbcL核苷酸序列进行了最大似然相对速率测试，并在不依赖类群间分歧时间知识的情况下，估计了序列组之间核苷酸替换速率的相对差异。速率测试表明，单子叶植物中rbcL基因座存在替换速率层次结构。在所分析的类群中，禾本科植物的替换速率最快；其次是兰目、百合目、凤梨目和棕榈目。禾本科植物rbcL基因座的总体替换速率是棕榈科植物rbcL替换速率的5倍多。禾本科植物rbcL第三个密码子位置的替换速率是棕榈科植物第三个位置速率的8倍多。速率变化模式与世代时间效应假说一致。替换速率的异质性对系统发育重建具有重要意义。
