Data from: Evolution of woody life form on tropical mountains in the tribe Spermacoceae (Rubiaceae)

Spermacoceae are mainly an herbaceous group in the Rubiaceae. However, a few lineages are woody, and are found in a diverse range of habitat types. Three of the largest woody lineages (Arcytophyllum, Hedyotis, and Kadua) are characterized by their distribution in the moist tropical mountains, and have disjunct distribution patterns with respect to their closest relatives. In this study, we explore the cases of derived woodiness in these three lineages and their diversification dynamics in the tropical mountains of Asia, the Pacific, and the Americas. By combining phylogenetic results with wood anatomical studies, we estimated timing of origin of the three woody groups, inferred their ancestral traits and ancestral distribution ranges, analyzed their associations with the tropical upland habitat, and elucidated their diversification across tropical mountains.
The three woody clades originated and diversified from herbaceous ancestors in close association with the tropical upland habitat during the Miocene. The ancestral range for Asian-Pacific Hedyotis and Pacific Kadua is Africa/Madagascar and continental Asia respectively. The complex geological history of tropical Asia allowed Hedyotis to diversify faster and create narrow endemics near oceans in the highlands of Western Ghats (India), Sri Lanka, Southeast Asia including southeastern China, and New Guinea. The three major woody clades in Spermacoceae have gained their woodiness independently from one another, subsequent to colonization by their ancestors from a different geographic environment. The evolution and diversification along the tropical mountain orogeny is strongly linked with the formation of woody habit and many narrow endemic species.

耳草族（Spermacoceae）是茜草科（Rubiaceae）中以草本为主的类群，但存在少数木本支系，分布于多样的生境类型中。其中三个规模最大的木本支系——Arcytophyllum、Hedyotis与Kadua——以分布于湿润热带山地为特征，且与各自的近缘类群呈现间断分布格局。本研究针对这三个支系的衍生木本性状，以及它们在亚洲、太平洋与美洲热带山地的多样化动态展开探究。研究结合系统发育结果与木材解剖学分析，估算了这三个木本类群的起源时间，推演了其祖先性状与祖先分布区，解析了它们与热带高地生境的关联，并阐明了其在热带山地间的多样化过程。
这三个木本支系均起源于草本祖先，并于中新世时期与热带高地生境紧密关联下完成多样化过程。分布于亚太区域的Hedyotis以及太平洋区域的Kadua，其祖先分布区分别为非洲/马达加斯加与亚洲大陆。热带亚洲复杂的地质历史使得Hedyotis的多样化速率更快，并在印度西高止山脉、斯里兰卡、包括中国东南部在内的东南亚地区以及新几内亚的滨海高地形成了诸多狭域特有种。耳草族的这三个主要木本支系，均是其祖先从不同地理环境扩散定居后，各自独立演化出木本性状的。沿热带山地造山运动的演化与多样化过程，与木本习性的形成以及诸多狭域特有种的产生密切相关。