Data from: Dispersal largely explains the Gondwanan distribution of the ancient tropical clusioid plant clade

PREMISE OF THE STUDY: The clusioid clade (Malpighiales) has an ancient fossil record (∼90 Ma) and extant representatives exhibit a pantropical distribution represented on all former Gondwanan landmasses (Africa, Australia, India, Madagascar, and South America) except Antarctica. Several biogeographers have hypothesized that the clusioid distribution is an example of Gondwanan vicariance. Our aim is to test the hypothesis that the modern distribution of the clusioid clade is largely explained by Gondwanan fragmentation. METHODS: Using a four gene, 207-taxon data set we simultaneously estimated the phylogeny and divergence times of the clusioid clade using a Bayesian Markov chain Monte Carlo approach. Ancestral Area Reconstructions (AARs) were then conducted on a distribution of 1000 trees and summarized on a reduced phylogeny. KEY RESULTS: Divergence time estimates and AARs revealed only two or four cladogenic events that are potentially consistent with Gondwanan vicariance, depending on the placement of the ancient fossil Paleoclusia. In contrast, dispersal occurred on > 25% of the branches, indicating the current distribution of the clade likely reflects extensive recent dispersal during the Cenozoic (< 65 Ma), most of which occurred after the beginning of the Eocene (∼56 Ma). CONCLUSIONS: These results support growing evidence that suggests many traditionally recognized angiosperm clades (families and genera) are too young for their distributions to have been influenced strictly by Gondwanan fragmentation. Instead, it appears that corridors of dispersal may be the best explanation for numerous angiosperm clades with Gondwanan distributions.研究背景：克鲁西亚类群（Clusioid clade，隶属于金虎尾目Malpighiales）拥有古老的化石记录（约90 Ma），其现生类群呈泛热带分布格局，除南极洲外，涵盖了所有前冈瓦纳大陆地块（非洲、澳大利亚、印度、马达加斯加及南美洲）。多位生物地理学者曾提出假说，认为该类群的现代分布是冈瓦纳隔离分化的典型案例。本研究旨在验证“克鲁西亚类群的现代分布格局主要由冈瓦纳大陆碎裂事件所主导”这一假说。 研究方法：本研究采用包含4个基因位点、207个分类单元的数据集，通过贝叶斯马尔可夫链蒙特卡洛（Bayesian Markov chain Monte Carlo）方法同时估算克鲁西亚类群的系统发育关系与分化时间。随后，基于1000棵系统发育树集合开展祖先区域重建（Ancestral Area Reconstructions，简称AARs），并将分析结果整合至简化后的系统发育树中进行汇总。 主要结果：分化时间估算与祖先区域重建结果显示，仅存在2或4次符合冈瓦纳隔离分化假说的分支发生事件，具体数量取决于古老化石类群古克鲁西亚属（Paleoclusia）的系统发育位置。与之形成鲜明对比的是，超过25%的系统发育分支发生过扩散事件，表明该类群的现代分布格局更可能反映了新生代（距今<65 Ma）时期广泛的近期扩散活动，其中绝大多数发生在始新世初期（约56 Ma）之后。 结论：本研究结果进一步支撑了日益增多的证据链，即诸多传统界定的被子植物类群（科与属）的演化时间过短，其分布格局无法完全由冈瓦纳大陆碎裂事件来解释。相较而言，扩散廊道假说似乎更能解释众多呈冈瓦纳分布格局的被子植物类群的起源与分布现状。