J Syst Evol

• Research Article •    

The origin and dispersal of Firmiana danxiaensis among isolated specific landscapes

Su‐Fang Chen1, Wan‐Yi Zhao1, Yan‐Shuang Huang1, Kai‐Kai Meng1, Kang‐You Huang2*, Rong‐Feng Hou3, Xiao‐Ying Luo4, Zai‐Xiong Chen3, Yuan‐Qiu Li5, Ren‐Chao Zhou1, Wen‐Bo Liao1, and Qiang Fan1*   

  1. 1 State Key Laboratory of Biocontrol and Guangdong Provincial Key Laboratory of Plant Resources, School of Life Sciences, Sun Yat‐sen University, Guangzhou 510275, China;
    2 School of Environmental Science and Engineering, Sun Yat‐sen University, Guangzhou 510275, China;
    3 Administrative Committee of Danxiashan National Park, Shaoguan 512300, Guangdong, China;
    4 College of Tourism and Geography, Shaoguan University, Shaoguan 512005, Guangdong, China;
    5 Guangdong Shimentai National Nature Reserve, Qingyuan 513000, Guangdong, China
    *Authors for correspondence. Qiang Fan. E‐mail: fanqiang@mail.sysu.edu.cn; Kang‐You Huang. E‐mail: hkangy@mail.sysu.edu.cn
  • Received:2022-10-27 Accepted:2023-03-28 Online:2023-05-11

Abstract: China has the most numerous Danxia and Karst landscapes, which serve as special terrestrial islands harboring ample endemic species, though how did these endemic species spread among those isolated sites is still an unresolved issue. To address this question, we explored the phylogeographical structure and demographic history of Firmiana danxiaensis, a tree species endemic to Danxia and Karst landscapes. We collected 295 samples (28 populations) of F. danxiaensis. Plastid genomes were assembled for 25 representative samples. Sanger sequencing of four plastid regions and restriction-site-associated DNA sequencing were performed on the 28 populations. The phylogenetic tree constructed from plastid genomes and restriction site-associated DNA sequencing (RAD-seq) data supported that F. danxiaensis originated from Mount Danxia and Nanxiong Basin, spread to Karst landscapes near Yingde City, and then back to Danxia Mountain and the Nanxiong Basin. In the Nanxiong Basin, the latter arrivals captured the plastid of the former. Population analyses revealed strong population structure among and within Danxia and Karst landscapes, possibly due to low seed and pollen dispersal abilities of the species. The demographic and ecological niche modeling approaches suggested that F. danxiaensis have widely occurred in the southeast of China during the last glacial period, and later retreated to the cliffs of Danxia and Karst landscapes due to temperature rising and competition failure. The declining of the effective population size of the species throughout the postglacial period suggested that global warming, agriculture, and industrial civilizations could have affected the survival of this species, and more measures should be taken to conserve these species.

Key words: Danxia and Karst landscapes, Firmiana danxiaensis, plastid genome assembly, population genomics, RAD‐seq