Duthieeae, a new tribe of grasses (Poaceae) identified among the early diverging lineages of subfamily Pooideae: molecular phylogenetics, morphological delineation, cytogenetics and biogeography
Duthieeae, a new tribe of grasses (Poaceae) identified among the early diverging lineages of subfamily Pooideae: molecular phylogenetics, morphological delineation, cytogenetics and biogeography
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DOI：
10.1080/14772000.2010.544339
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发表时间：
2011-03
影响因子：
1.9
通讯作者：
J. Schneider;G. Winterfeld;M. Hoffmann;M. Röser
中科院分区：
文献类型：
--
作者：
J. Schneider;G. Winterfeld;M. Hoffmann;M. Röser
禾本科是禾本科中最大的亚科之一，近年来对禾本科的系统发育进行了深入的研究。为了研究Pooideae的早期进化分裂，我们使用了大量的不确定位置的属样本，其中一些以前没有在分子系统发育中研究过，并补充了该亚科其他谱系的代表。在叶绿体matK-3'trnK和细胞核ITS分子序列的基础上，增加了形态学、细胞遗传学和生物地理学分析。根据叶绿体DNA数据，在早期分支中发现了一个新的和有良好支持的谱系。它由Phaenosperma和一个更大的属群组成，包括Anisopogon、Danthoniastrum、duthia、Metcalfia、Pseudodanthonia（包括在ITS和形态学上）、Sinochasea和Stephanachne。根据结构特征，我们建议将Phaenosperma保留在单型部落Phaenospermateae下，并将其他属容纳在一个新的部落duthieae下，该部落在形态上以幼胚性的小穗特征划分。Megalachne和Podophorus不是早期分化的Pooideae谱系的一部分，而是属于Aveneae/Poeae复合体。讨论了duthieae的形态特征，特别是Stipeae，并揭示了两个部落之间的一致差异。划分了杜鹃属和杜鹃属的主要谱系。对典型类群的细胞遗传学调查证实，高染色体碱基数在早期分化谱系中普遍存在，但染色体大小的变化比以前报道的要大。生态地理分析指出，温暖和潮湿的环境是Phaenosperma和Duthieeae祖先的生物气候生态位，而Duthieeae对寒冷和干旱的适应只发生在Duthieeae的一部分，但明显不如广泛分布且物种丰富的Stipeae部落成功。在北半球山区分布的贫种或单型属duthieae和在澳大利亚分布的异角亚纲（Anisopogon）显示出孑遗的特征。
The phylogeny of Pooideae, one of the largest subfamilies of grasses, has been intensively studied during the past years. To investigate the early evolutionary splits in Pooideae we used a broad sample of genera with uncertain placement, some of which have not been studied in molecular phylogenetics before, complemented by representatives from other lineages of this subfamily. Morphological, cytogenetic and biogeographical analyses were added to the molecular sequence work on chloroplast matK–3’trnK and nuclear ITS. According to chloroplast DNA data, a new and well-supported lineage was identified among the early branches. It consisted of Phaenosperma and a larger group of genera encompassing Anisopogon, Danthoniastrum, Duthiea, Metcalfia, Pseudodanthonia (inclusion resting on ITS and morphology), Sinochasea and Stephanachne. Based on structural characters we suggest to keep Phaenosperma under the monotypic tribe Phaenospermateae and to accommodate the other genera under a new tribe Duthieeae, which is morphologically well-defined by synapomorphic spikelet features. Megalachne and Podophorus were not part of the early diverging Pooideae lineages but belong to the Aveneae/Poeae complex. Morphological characteristics of Duthieeae are discussed with respect especially to Stipeae and reveal consistent differences between both tribes. The genera of Duthieeae and the major lineages of Stipeae are keyed. A cytogenetic survey of exemplary taxa corroborates high chromosome base numbers as prevailing within the early diverging lineages of Pooideae, but chromosome sizes are more highly varied than previously reported. Ecogeographical analyses point to warm and humid conditions as the ancestral bioclimatic niche of Phaenosperma and Duthieeae, whereas adaptation to cold and drought occurred only in a part of Duthieeae but was obviously less successful than in the widespread and much more species-rich tribe Stipeae. The distribution of Duthieeae with species-poor or monotypic genera in mountains of the northern hemisphere and Anisopogon as an outlier in Australia suggests relict character.