A rich fossil record yields calibrated phylogeny for Acanthaceae (Lamiales) and evidence for marked biases in timing and directionality of intercontinental disjunctions

More than a decade of phylogenetic research has yielded a well-sampled, strongly supported hypothesis of relationships within the large (> 4,000 species) plant family Acanthaceae. This hypothesis points to intriguing biogeographic patterns and asymmetries in sister clade diversity but, absent a time-calibrated estimate for this evolutionary history, these patterns have remained unexplored. Here, we reconstruct divergence times within Acanthaceae using fossils as calibration points, experimenting both with fossil selection and effects of invoking a maximum age prior related to the origin of Eudicots. Contrary to earlier reports of a paucity of fossils of Lamiales (an order of ~23,000 species that includes Acanthaceae) and to the expectation that a largely herbaceous to soft-wooded and tropical lineages would have few fossils, we recovered 51 reports of fossil Acanthaceae. Rigorous evaluation of these for accurate identification, quality of age assessment, and utility in dating yielded...十余年来的系统发育研究已为包含超4000个物种的大型植物科——爵床科（Acanthaceae）——构建出采样完备、支持度优异的系统发育关系假说。该假说揭示了耐人寻味的生物地理格局与姐妹支系多样性的不对称性，但由于缺乏针对该演化历程的时间校准估算结果，此类格局始终未能得到深入探究。本研究以化石作为校准点，重建爵床科的分化时间；同时开展了化石筛选试验，并评估了引入与真双子叶植物（Eudicots）起源相关的最大年龄先验所带来的影响。此前有研究称唇形目（Lamiales，一个包含爵床科、拥有约23000个物种的类群）的化石较为匮乏，且学界普遍认为以草本为主、兼具软木质特征的热带支系类群的化石记录稀少；但我们此次共检索到51份爵床科化石记录。我们对这些化石的分类鉴定准确性、年代评估质量以及定年分析的实用性开展了严格评估，最终得到……