Elucidating deep-level phylogenetic relationships in Saxifragaceae using sequences for six chloroplastic and nuclear DNA regions
Elucidating deep-level phylogenetic relationships in Saxifragaceae using sequences for six chloroplastic and nuclear DNA regions
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DOI：
10.2307/3298639
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发表时间：
2001-01-01
影响因子：
1.9
通讯作者：
Arroyo, MK
中科院分区：
文献类型：
--
作者：
Soltis, DE;Kuzoff, RK;Arroyo, MK
为了阐明Suxifragaceae内深层次的关系，我们分析了6个DNA区域的序列数据集，其中4个代表叶绿体基因组（rbcL，matK，trnL-trnF，psbA-trnH），2个来自核基因组（ITS和26 S rDNA的扩展片段）。每个分类单元的序列长度为6676 bp，叶绿体和核基因组的序列长度分别为4559 bp和1878 bp。叶绿体和核树的结果非常一致，这促使了对一个组合的六基因数据集的分析。简约性和最大似然方法的应用产生了类似的拓扑结构。使用不同的ITS比对和排除难以比对的ITS区域对最终的基于核的拓扑结构或来自六个基因分析的最短树几乎没有影响。阐明了火地岛特有的两个单型属（虎耳草属和虎耳草属）的亲缘关系。虎耳草属（Saxifragella）是北温带虎耳草属（Saxifraga s.）str.;虎耳草是卡斯卡迪亚的姐妹，卡斯卡迪亚是俄勒冈州和华盛顿特有的属。从东亚或北美洲西部到南美洲的长距离扩散可能在形成这些和其他类似的科中的disjuctions方面发挥了重要作用。一些支持良好的分支存在，包括虎耳草。str. Micranthes，虎耳草属/落新妇属，金腰属/Peltoboyknia，以及Boykinia和Heuchera类群。额外字符的使用大大提高了分辨率，并在深层提供了内部支持。虎耳草科包括两个主要谱系：虎耳草属。str.（包括虎耳草属）和所有其他属的家庭（heucheroids）。这种主要的分裂伴随着一般的地理和形态的差异。而虎耳草S.主要分布于北极至高山，而Heucheroid分支则主要分布于温带。虎耳草属str.有一个相对统一的花的形态（通常辐射对称; 5萼片，5花瓣，10雄蕊，2心皮），而heucheroid分支包括辐射对称和左右对称的形式，以及在萼片，花瓣，雄蕊和心皮的数量变化。两种虎耳草的深层关系。str.和heucheroid分支得到很好的解决和支持。提供了该科的系统发育分类。
To elucidate relationships at deep levels within Suxifragaceae we analyzed phylogenetically a data set of sequences for six DNA regions, four representing the chloroplast genome (rbcL, matK, trnL-trnF, psbA-trnH) and two from the nuclear genome (ITS and expansion segments of the 26S rDNA). A total of 6676 bp was aligned per taxon, 4559 bp and 1878 bp from the chloroplast and nuclear genomes, respectively. Chloroplast and nuclear trees agreed closely, prompting analysis of a combined, six-gene data set. Application of both parsimony and maximum likelihood methods yielded similar topologies. The use of different ITS alignments and the exclusion of hard-to-align ITS regions had little impact on either the final nuclear-based topology, or the shortest trees from the analysis of six genes. The affinities of two monotypic genera (Saxifragella and Saxifragodes) endemic to Tierra del Fuego were elucidated. Saxifragella is an early branching member of the North Temperate genus Saxifraga s. str.; Saxifragodes is sister to Cascadia, a genus endemic to Oregon and Washington. Long-distance dispersal from east Asia or western North America to South America may have played an important role in forming these and other similar disjuctions in the family. A number of well-supported clades are present, including Saxifraga s. str. Micranthes, Saxifragopsis/Astilbe, Chrysosplenium/Peltoboyknia, and the Boykinia and Heuchera groups. The use of additional characters has provided greatly increased resolution and internal support at deep levels. Saxifragaceae comprise two major lineages: Saxifraga s. str. (including Saxifragella) and all other genera of the family (the heucheroids). This major split is accompanied by general biogeographical and morphological differences. Whereas Saxifraga s. str. is largely arctic to alpine in occurrence, the heucheroid clade is largely temperate in distribution. Saxifraga s. str. has a relatively uniform floral morphology (generally actinomorphic; 5 sepals, 5 petals, 10 stamens, 2 carpels), whereas the heucheroid clade encompasses actinomorphic and zygomorphic forms, as well as variation in the number of sepals, petals, stamens, and carpels. Deep-level relationships within both Saxifraga s. str. and the heucheroid clade are well resolved and supported. A phylogenetic classification of the family is provided.