PHYLOGENETICS OF SEED PLANTS - AN ANALYSIS OF NUCLEOTIDE-SEQUENCES FROM THE PLASTID GENE RBCL
PHYLOGENETICS OF SEED PLANTS - AN ANALYSIS OF NUCLEOTIDE-SEQUENCES FROM THE PLASTID GENE RBCL
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DOI：
10.2307/2399846
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发表时间：
1993-01-01
影响因子：
1.9
通讯作者：
ALBERT, VA
中科院分区：
文献类型：
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作者：
CHASE, MW;SOLTIS, DE;ALBERT, VA
我们分别对来自475种和499种种子植物的DNA序列进行了两次探索性简约分析，这些植物代表了所有主要分类群。数据完全来自叶绿体基因rbcL，它编码核酮糖 - 1,5 - 二磷酸羧化酶/加氧酶（RuBisCO或RuBPCase）的大亚基。我们使用了两种不同的状态转换假设，得出了两组分支图：（i）对499个分类单元的分析采用等权重；（ii）在对475个分类单元的分析中，采用一种对字符内的颠换和转换以及字符间的密码子位置进行差异加权的方法。这些结果与其他分子以及形态分支系统学研究之间的一致性程度表明，rbcL序列变异包含适合在这种分类取样水平上进行系统发育分析的历史证据。由于所呈现的拓扑结构必然是近似的，并且无法对内部支持进行充分评估，因此这些结果应从其预测价值的角度进行评估，并用于指导未来的分子和形态研究。在这两次分析中，买麻藤目的三个属被归为一类，作为开花植物的姊妹群，而特殊的水生植物金鱼藻（金鱼藻科）是所有其他开花植物的姊妹群。所确定的几个主要谱系与至少一些近期的被子植物分类方案，特别是达尔格伦和索恩的方案，吻合得很好。被子植物中最基部的分支是明显多系的木兰亚纲（按克朗奎斯特的定义）的目。该拓扑结构最显著的特征是主要的划分不是单子叶植物与双子叶植物的划分，而是与一般花粉类型相关的划分：单沟花粉与三沟花粉。五桠果亚纲和金缕梅亚纲是仅有的严重多系的亚纲；对后者的研究作为一个例子，展示了如何利用这些广泛的分析来聚焦更具局限性的研究。一个广义界定的蔷薇亚纲对于菊亚纲和五桠果亚纲是并系的。石竹亚纲在475个分类单元的分析中是单系的，且源自蔷薇亚纲内部，但在499个分类单元的研究中是由广义界定的菊亚纲和蔷薇亚纲组成的一个类群的姊妹群。
We present the results of two exploratory parsimony analyses of DNA sequences from 475 and 499 species of seed plants, respectively, representing all major taxonomic groups. The data are exclusively from the chloroplast gene rbcL, which codes for the large subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO or RuBPCase). We used two different state-transformation assumptions resulting in two sets of cladograms: (i) equal-weighting for the 499-taxon analysis; and (ii) a procedure that differentially weights transversions over transitions within characters and codon positions among characters for the 475-taxon analysis. The degree of congruence between these results and other molecular, as well as morphological, cladistic studies indicates that rbcL sequence variation contains historical evidence appropriate for phylogenetic analysis at this taxonomic level of sampling. Because the topologies presented are necessarily approximate and cannot be evaluated adequately for internal support, these results should be assessed from the perspective of their predictive value and used to direct future studies, both molecular and morphological. In both analyses, the three genera of Gnetales are placed together as the sister group of the flowering plants, and the anomalous aquatic Ceratophyllum (CeratophyUaceae) is sister to all other flowering plants. Several major lineages identified correspond well with at least some recent taxonomic schemes for angiosperms, particularly those of Dahlgren and Thorne. The basalmost clades within the angiosperms are orders of the apparently polyphyletic subclass Magnoliidae sensu Cronquist. The most conspicuous feature of the topology is that the major division is not monocot versus dicot, but rather one correlated with general pollen type: uniaperturate versus triaperturate. The Dilleniidae and Hamamelidae are the only subclasses that are grossly polyphyletic; an examination of the latter is presented as an example of the use of these broad analyses to focus more restricted studies. A broadly circumscribed Rosidae is paraphyletic to Asteridae and Dilleniidae. Subclass Caryophyllidae is monophyletic and derived from within Rosidae in the 475-taxon analysis but is sister to a group composed of broadly delineated Asteridae and Rosidae in the 499-taxon study.