Molecular phylogenetics, morphology and a revised classification of the complex genus Saxifraga (Saxifragaceae)
Molecular phylogenetics, morphology and a revised classification of the complex genus Saxifraga (Saxifragaceae)
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DOI：
10.12705/646.4
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发表时间：
2015-12-31
期刊：
影响因子：
3.4
通讯作者：
Hoffmann, Matthias H.
中科院分区：
文献类型：
--
作者：
Tkach, Natalia;Roeser, Martin;Hoffmann, Matthias H.
虎耳草属是虎耳草科中物种最丰富、分类最复杂的属，是北半球温带至极地气候带以及山地至高山植被带的特征组成部分。该属包含 440 多个物种，在生长形式、营养和生殖特征以及花粉粒和种子的微形态方面表现出显着的多样性。使用包括几乎所有公认的虎耳草亚属、部分和亚类（总共 254 个物种）的代表在内的大型分类单元集，以及广泛的外群类群覆盖范围，我们推断了虎耳草内部的进化关系，探索了虎耳草先前分类处理之间显着不一致的原因，估计了经常用于分类的性状的同质性程度，评估了杂交在该属进化中的作用，最后，提供了一个基于系统发育的框架来修改其分类法。基于核核糖体内转录间隔区 (ITS) 和质体 trnL-trnF DNA 标记的系统发育树，包括 460 多个新生成的序列，通常高度一致，但在单个进化枝（虎耳草组）内除外，其中不完整的谱系排序和可能的异源多倍体物种形成发挥着重要的进化作用。虎耳草的主要谱系由来自两个细胞器的 DNA 标记一致解析，并且大多具有强大的节点支持。我们的分子系统发育结果支持对虎耳草内至少 13 个部分和 9 个亚部分的识别。这些谱系的一部分与先前公认的属下类群非常吻合，而其他谱系则有不同的描述。通过分子系统发育学鉴定的一些类群仅通过不同形态特征的组合来表征。通常，微形态特征相对较好地支持系统发育树中的进化枝。我们在这里为三个非通用绰号提供新的等级，即教派。虎耳草亚科。穿心莲科及其亚科。蛛形纲和组。卟啉亚科。方节。最后，我们的研究确定了虎耳草属中剩余的分类学不确定性。
Saxifraga, the most species-rich and taxonomically complex genus of Saxifragaceae, is a characteristic component of temperate to polar climatic zones and of montane to alpine vegetation belts in mountain ranges of the Northern Hemisphere. The genus encompasses more than 440 species, which display notable diversity in growth form, vegetative and reproductive characters, as well as in micromorphology of pollen grains and seeds. Using a large taxon set including representatives attributed to nearly all recognised subgenera, sections and subsections of Saxifraga (altogether 254 species), as well as a broad coverage of outgroup taxa, we inferred evolutionary relationships within Saxifraga, explored the reasons of the striking inconsistencies between previous taxonomic treatments of Saxifraga, estimated the degree of homoplasy in characters frequently employed for classification, assessed the role of hybridisation in the evolution of the genus and, finally, provided a phylogeny-based framework upon which to revise its taxonomy. The phylogenetic trees based on nuclear ribosomal internal transcribed spacer (ITS) and plastid trnL-trnF DNA markers, including more than 460 newly generated sequences, were generally highly congruent, except within a single clade (sect. Saxifraga), in which incomplete lineage sorting and presumably allopolyploid speciation plays an important evolutionary role. Major lineages of Saxifraga are concordantly resolved by the DNA markers from both organelles with mostly strong node support. Our molecular phylogenetic results support the recognition of at least 13 sections and 9 subsections within Saxifraga. A part of these lineages agrees well with previously recognised infrageneric groupings, whereas others are differently delineated. Some of the groups identified by molecular phylogenetics are characterised only by the combination of different morphological characters. Frequently, micromorphological characters support the clades in the phylogenetic tree comparatively well. We here provide new ranks for three infrageneric epithets, namely for sect. Saxifraga subsect. Androsaceae and subsect. Arachnoideae and sect. Porphyrion subsect. Squarrosae. Finally, our study identifies remaining taxonomic uncertainties within Saxifraga.