Ulmaceae is a woody family widespread in northern temperate forests. Despite the ecological importance of this family, its phylogeny and biogeographic history are poorly understood. In this study, we reconstruct phylogenetic relationships within the family and infer spatio-temporal diversification patterns based on chloroplast genome (complete cpDNA) and nuclear ribosomal DNA sequences (nrDNA). The seven Ulmaceae genera are resolved in two main clades (temperate vs. tropical) by both cpDNA and nrDNA sequences. The temperate clade includes four genera, Hemiptelea, Zelkova, Planera, and Ulmus. The relationships among Planera and other genera are controversial because of inconsistent topologies between plastid and nuclear data. The tropical clade includes three genera ((Ampelocera, Phyllostylon), Holoptelea). Molecular dating and diversification analyses show that Ulmaceae originated in the Early Cretaceous (ca. 110–125 Ma) with the main lineages establishing from the Late Cretaceous to the early Eocene. The diversification rate slowed during the middle to the late Paleogene (ca. 23–45 Ma), followed by a rapid diversification of the East Asian temperate group in the Neogene, congruent with a global cooling event. The ancestral state optimization analysis suggests an East Asian origin of the temperate Ulmaceae clade during the Paleocene, which is consistent with the fossil record. Both phylogenomic and fossil evidence support East Asia as a center of origin and diversification for the temperate woody lineages.

中文翻译：

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北部温带木本植物区系的多样化——基于系统发育和古植物学证据的榆科（榆科）案例研究

榆科是广布于北部温带森林的木本科。尽管这个家庭的生态重要性，它的系统发育和生物地理历史知之甚少。在这项研究中，我们重建了家族内的系统发育关系，并基于叶绿体基因组（完整的 cpDNA）和核核糖体 DNA 序列（nrDNA）推断时空多样化模式。cpDNA 和 nrDNA 序列在两个主要进化枝（温带与热带）中解析了 7 个榆科属。温带进化枝包括四个属，半翅目属、榉属、刨花属和榆属。Planera之间的关系由于质体和核数据之间的拓扑结构不一致，其他属存在争议。热带进化枝包括三个属 (( Ampelocera , Phyllostylon ), Holoptelea）。分子测年和多样化分析表明，榆科起源于早白垩世（约110-125 Ma），主要谱系建立于晚白垩世至始新世早期。在古近纪中晚期（约 23-45 Ma），多样化速度放缓，随后在新近纪东亚温带组迅速多样化，与全球变冷事件相一致。祖先状态优化分析表明，古新世温带榆科进化枝起源于东亚，这与化石记录一致。系统发育和化石证据都支持东亚作为温带木本谱系的起源和多样化中心。