Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.
Laboratoire de Systématique Végétale et Biodiversité, University of Geneva, Geneva, Switzerland.
PLoS One. 2018 Dec 5;13(12):e0207615. doi: 10.1371/journal.pone.0207615. eCollection 2018.
The Rubiaceae tribe Rubieae has a world-wide distribution with up to 1,000 species. These collectively exhibit an enormous ecological and morphological diversity, making Rubieae an excellent group for macro- and microevolutionary studies. Previous molecular phylogenetic analyses used only a limited sampling within the tribe or missed lineages crucial for understanding character evolution in this group. Here, we analyze sequences from two plastid spacer regions as well as morphological and biogeographic data from an extensive and evenly distributed sampling to establish a sound phylogenetic framework. This framework serves as a basis for our investigation of the evolution of important morphological characters and the biogeographic history of the Rubieae. The tribe includes three major clades, the Kelloggiinae Clade (Kelloggia), the Rubiinae Clade (Didymaea, Rubia) and the most species-rich Galiinae Clade (Asperula, Callipeltis, Crucianella, Cruciata, Galium, Mericarpaea, Phuopsis, Sherardia, Valantia). Within the Galiinae Clade, the largest genera Galium and Asperula are para- and polyphyletic, respectively. Smaller clades, however, usually correspond to currently recognized taxa (small genera or sections within genera), which may be used as starting points for a refined classification in this clade. Life-form (perennial versus annual), flower shape (long versus short corolla tube) and fruit characters (dry versus fleshy, with or without uncinate hairs) are highly homoplasious and have changed multiple times independently. Inference on the evolution of leaf whorls, a characteristic feature of the tribe, is sensitive to model choice. Multi-parted leaf whorls appear to have originated from opposite leaves with two small interpetiolar stipules that are subsequently enlarged and increased in number. Early diversification of Rubieae probably started during the Miocene in western Eurasia. Disjunctions between the Old and the New World possibly are due to connections via a North Atlantic land bridge. Diversification of the Galiineae Clade started later in the Miocene, probably in the Mediterranean, from where lineages reached, often multiple times, Africa, eastern Asia and further on the Americas and Australia.
茜草科Rubieae 族分布于世界各地，约有 1000 种。这些植物表现出巨大的生态和形态多样性，使得 Rubieae 成为宏观和微观进化研究的理想群体。以前的分子系统发育分析仅在该族内进行了有限的采样，或者错过了对该组特征进化至关重要的谱系。在这里，我们分析了来自两个质体间隔区的序列以及广泛而均匀分布的采样的形态和生物地理数据，以建立一个健全的系统发育框架。该框架是我们研究重要形态特征进化和 Rubieae 生物地理历史的基础。该族包括三个主要分支，Kelloggiinae 分支（Kelloggia），Rubiinae 分支（Didymaea，Rubia）和物种最丰富的Galiinae 分支（Asperula，Callipeltis，Crucianella，Cruciata，Galium，Mericarpaea，Phuopsis，Sherardia，Valantia）。在 Galiinae 分支中，最大的属 Galium 和 Asperula 分别是并系和多系的。然而，较小的分支通常对应于当前公认的分类群（属内的小属或部分），它们可以作为该分支中更精细分类的起点。生活型（多年生与一年生），花形（长而短的花冠管）和果实特征（干燥与肉质，有无钩状毛）高度同形，并且已经多次独立发生变化。对该族特征的叶轮演化的推断对模型选择敏感。多部分的叶轮似乎起源于具有两个小的叶柄间托叶的对生叶，随后托叶扩大并增加数量。Rubieae 的早期多样化可能始于中新世的西欧亚大陆。旧大陆和新大陆之间的间断可能是由于北大西洋陆桥的连接造成的。Galiineae 分支的多样化始于中新世晚期，可能在地中海，从那里的谱系多次到达非洲，东亚，再到美洲和澳大利亚。
