Department of Botany, University of Hawai'i, Mānoa, 3190 Maile Way, Honolulu, Hawaii, 96822, USA.
Department of Biology, San Francisco State University, 1600 Holloway Avenue, San Francisco, California, 94132, USA.
Am J Bot. 2021 Mar;108(3):505-519. doi: 10.1002/ajb2.1614. Epub 2021 Mar 5.
With over 1500 species, the globally distributed Vernonieae is one of the most successful members of the largest family of flowering plants, the Compositae. However, due to its morphological complexity and limited geographic representation in previous studies, subtribal and biogeographic relationships are unclear. Here, new DNA sequence data spanning the geographic range of the tribe provides a taxonomically robust time-calibrated phylogeny, estimates migration pathways and timing of important biogeographic events, and allows inference of environmental factors that have contributed to the success of the Vernonieae worldwide.
Phylogenetic relationships were estimated for 368 taxa representing all Vernonieae subtribes. Molecular clock and ancestral range estimation analyses provide a framework for inference of the biogeographic history of the tribe.
Relationships among the subtribes were established and correct placement determined for problematic taxa, along with the first model-based assessment of the biogeographic history of the tribe. The Vernonieae were estimated to have evolved ~50 mya. Africa was the first center of diversity, from which a single dispersal event established the monophyletic New World lineage. Long-distance dispersal from Africa and Brazil established the tribe on five continents and Oceania.
The New World lineage is monophyletic, but Old World taxa are not. New subtribal taxonomies are needed. Moquinieae are nested in Vernonieae. Long-distance dispersal from Africa beginning 45 mya was key to establishing the tribe's near-global distribution. Migration corridors created by volcanic mountain chains and iron-rich soils in Africa and the Americas promoted radiation and range expansion.
Vernonieae 是全球分布最广的成员之一，隶属于最大的开花植物科——菊科，拥有超过 1500 个物种。然而，由于其形态复杂，以及在以前的研究中地理代表性有限，亚族和生物地理关系尚不清楚。在这里，新的 DNA 序列数据跨越了该部落的地理范围，提供了一个分类学上稳健的时间校准系统发育，估计了重要生物地理事件的迁移途径和时间，并允许推断出有助于 Vernonieae 在全球范围内成功的环境因素。
对代表 Vernonieae 所有亚族的 368 个分类单元进行了系统发育关系估计。分子钟和祖先范围估计分析为推断该部落的生物地理历史提供了框架。
确定了亚族之间的关系，并确定了有问题的分类单元的正确位置，以及首次基于模型的对该部落生物地理历史的评估。Vernonieae 估计在 5000 万年前进化而来。非洲是第一个多样性中心，从那里发生了一次单一的扩散事件，建立了单系的新大陆谱系。从非洲和巴西的远距离扩散使该部落分布在五大洲和大洋洲。
新大陆谱系是单系的，但旧世界的分类单元不是。需要新的亚族分类学。Moquinieae 嵌套在 Vernonieae 中。4500 万年前从非洲开始的远距离扩散是建立该部落近全球分布的关键。由火山山脉和非洲及美洲的富铁土壤形成的迁移走廊促进了辐射和范围的扩张。
