Myers P, Lundrigan B, Tucker P K
Museum of Zoology, University of Michigan, Ann Arbor 48109, USA.
Mol Phylogenet Evol. 1995 Dec;4(4):372-82. doi: 10.1006/mpev.1995.1035.
Cytochrome b sequences (401 bp) were used to investigate the phylogenetic relationships of a group of South American rodents. The study focused on the tribe Oryzomyini (Family Muridae, Subfamily Sigmodontinae) and two of its genera, Oryzomys and Oligoryzomys, especially the latter. Genetic distances separating Oryzomys species average 19%, while those separating Oligoryzomys species are much smaller (mean 11%). When analyzed cladistically, cytochrome b sequences provide weak support for the monophyly of Oryzomyini, but strong evidence for paraphyly of Oryzomys. The cladogram supports the monophyly of Oligoryzomys; however, the branching pattern among its species suggests evolutionary relationships that conflict with hypotheses based on morphology and allozymes. In these taxa, sequences of nucleotides making up cytochrome b violate an important assumption of phylogenetic analysis, independence of characters. The implications of this finding are discussed for phylogeny reconstruction and the measurement of support for cladograms.
细胞色素b序列（401个碱基对）被用于研究一组南美洲啮齿动物的系统发育关系。该研究聚焦于稻鼠族（鼠科，稻鼠亚科）及其两个属，稻鼠属和小稻鼠属，尤其侧重于后者。区分稻鼠属物种的遗传距离平均为19%，而区分小稻鼠属物种的遗传距离则小得多（平均为11%）。当进行分支分析时，细胞色素b序列对稻鼠族的单系性提供了微弱支持，但对稻鼠属的并系性提供了有力证据。分支图支持小稻鼠属的单系性；然而，其物种间的分支模式表明进化关系与基于形态学和等位酶的假设相冲突。在这些分类群中，构成细胞色素b的核苷酸序列违反了系统发育分析的一个重要假设，即特征的独立性。本文讨论了这一发现对系统发育重建以及分支图支持度测量的影响。
