matK and rbcL gene sequence data indicate that Saxifraga (Saxifragaceae) is polyphyletic
matK and rbcL gene sequence data indicate that Saxifraga (Saxifragaceae) is polyphyletic
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DOI：
10.2307/2446171
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发表时间：
1996-03-01
影响因子：
3
通讯作者：
Ferguson, K
中科院分区：
文献类型：
--
作者：
Soltis, DE;Kuzoff, RK;Ferguson, K
虎耳草属由 2400 个形态和细胞学不同的物种组成，长期以来一直被认为在分类学上非常复杂。对来自 matK 和 rbcL 的超过 2500 bp 的叶绿体序列数据进行系统发育分析，用于检查虎耳草属、Zahlbrucknera 分离属、虎耳草属和卡斯卡迪亚属各部分之间的关系，以及这些类群与其他虎耳草科意义上的关系。对 matK 和 rbcL 序列进行单独分析得出的系统发育树高度一致；因此，还对组合的 matK-rbcL 数据矩阵进行了系统发育分析。我们的分析表明虎耳草是多系的，包含两个分化良好的分支。其中一个进化枝，虎耳草属（Saxifraga sensu stricto），是该科其余成员的姐妹，由虎耳草科不规则目（Irregulares）、异形虎耳草（Heterisia）、粗叶虎耳属（Trachyphyllum）、伞形目（Cymbalaria）、中雌性（Mesogyne）、Xanrhizoon、卟啉科（Porphyrion）、纤毛科（Ciliarae）、子叶科（Cotylea）、橐吾科（Ligulatae）、虎耳草科（Saxifraga）和裸露科（Gymnogera）组成。除了 Gymnopera 之外，该分支中物种丰富的部分都是单系的。该分支的一部分是有问题的 Zahlbrucknera paradoxa，它与虎耳草部分的成员有联系。虎耳草属的第二个主要分支，Micuanthes sensu Late，包括大的Micranthes科，以及分离的Cascadia属和Merkianae科的S. tolmiei。该分支与 Heuchera、Darmera 和 Chlysosplenhm-Peltoboykinia 属群体有联系。分离属虎耳草属仅与虎耳草属有远缘关系，而是落新妇属的姐妹。单型 Oresitrope 被确认为 Darmera 属的一员。这些结果表明，用于定义虎耳草属的花特征可能只是在这些分离良好的虎耳草属谱系中是同形的。此外，虎耳草所包含的巨大细胞学多样性可能代表了虎耳草科中广泛的非整倍体和多倍体的两个独立实例。
The large genus Saxifraga, which consists of 2400 morphologically and cytologically diverse species, has long been considered taxonomically complex. Phylogenetic analysis of over 2500 bp of chloroplast sequence data derived from matK and rbcL was employed to examine relationships among sections of Saxifraga, the segregate genera Zahlbrucknera, Saxifragopsis, and Cascadia, and the relationships of these taxa to other Saxifragaceae sensu stricto. Phylogenetic trees resulting from separate analyses of the matK and rbcL sequences were highly congruent; phylogenetic analysis of a combined matK-rbcL data matrix was therefore also conducted. Our analyses indicate that Saxifraga is polyphyletic, comprising two well-differentiated clades. One clade, Saxifraga sensu stricto, is the sister to the remainder of the family and consists of Saxifraga sections Irregulares, Heterisia, Trachyphyllum, Cymbalaria, Mesogyne, Xanrhizoon, Porphyrion, Ciliarae, Cotylea, Ligulatae, Saxifraga, and Gymnogera. With the exception of Gymnopera, the species-rich sections of this clade are monophyletic, Also part of this clade is the problematic Zahlbrucknera paradoxa, which is allied with members of section Saxifraga. A second major clade of Saxifraga species, Micuanthes sensu late, comprises the large section Micranthes, as well as the segregate genus Cascadia, and S. tolmiei of section Merkianae. This clade is allied with the Heuchera, Darmera, and Chlysosplenhm-Peltoboykinia groups of genera. The segregate genus Saxifragopsis is only distantly related to species of Saxifraga, and is instead the sister to Astilbe. The monotypic Oresitrophe is confirmed as a member of the Darmera group of genera. These results suggest that the floral features used to define Saxifraga may simply be symplesiomorphic in these well-separated Saxifraga lineages. Furthermore, the enormous cytological diversity encompassed by Saxifraga likely represents two independent instances of extensive aneuploidy and polyploidy in Saxifragaceae.