Journal of Systematics and Evolution

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  • 收稿日期:2020-04-18 接受日期:2020-12-18

The diversification of the northern temperate woody flora – a case study of the Elm family (Ulmaceae) based on phylogenomic and paleobotanical evidence

Qiuyue Zhang1, 2, 6, Min Deng3, Yanis Bouchenak-Khelladi4, Zhekun Zhou1, 2, 5, Guangwan Hu7,8, Yaowu Xing1, 2*   

  1. 1Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Xishuangbanna, Yunnan 666303, China

    2Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Xishuangbanna, Yunnan 666303, China

    3School of Ecology and Environmental Science, Yunnan University, Kunming 650500, China

    4Université de Bourgogne Franche-Comté, UMR Biogéosciences CNRS 6282, 6 boulevard Gabriel, 21000 Dijon, France

    5Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China

    6University of Chinese Academy of Sciences, Beijing 100049, China

    7Key Laboratory of Plant Germplasm Enhancement and Specialty Agriculture, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China

    8Sino-Africa Joint Research Center, Chinese Academy of Sciences, Wuhan 430074, China

  • Received:2020-04-18 Accepted:2020-12-18

Abstract: Ulmaceae are 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 comprising the family 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 shows 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.

Key words: Biogeography, Diversification, Fossil, Phylogeny, Temperate biome, Ulmaceae