Plant Diversity ›› 2021, Vol. 43 ›› Issue (06): 462-471.DOI: 10.1016/j.pld.2021.04.002

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Evolutionary history of a desert perennial Arnebia szechenyi (Boraginaceae): Intraspecific divergence, regional expansion and asymmetric gene flow

Meng-Jiao Fua, Hai-Yang Wua, Dong-Rui Jiab, Bin Tiana,c   

  1. a Key Laboratory for Forest Resources Conservation and Utilization in the Southwest Mountains of China, Ministry of Education, Southwest Forestry University, Kunming 650224, China;
    b School of Ecology and Environmental Science&Yunnan Key Laboratory for Plateau Mountain Ecology and Restoration of Degraded Environments, Yunnan University, Kunming 650091, China;
    c CAS Key Laboratory for Plant Diversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China
  • Received:2021-02-07 Revised:2021-04-07 Online:2021-12-25 Published:2022-01-11
  • Contact: Dong-Rui Jia, Bin Tian
  • Supported by:
    We are grateful to Dr. Jun-Wei Ye for assistant on data analysis. We thank Dr. Yuan-Wen Duan for help during the field survey. This study was supported by the National Natural Science Foundation of China (41861008), Science Foundation of Yunnan Education Department (2018JS347), and the Ten-thousand Talents Program of Yunnan Province (YNWR-QNBJ-2020).

Abstract: The complex interactions of historical, geological and climatic events on plant evolution have been an important research focus for many years. However, the role of desert formation and expansion in shaping the genetic structures and demographic histories of plants occurring in arid areas has not been well explored. In the present study, we investigated the phylogeography of Arnebia szechenyi, a desert herb showing a near-circular distribution surrounding the Tengger Desert in Northwest China. We measured genetic diversity of populations using three maternally inherited chloroplast DNA (cpDNA) fragments and seven bi-paternally inherited nuclear DNA (nDNA) loci that were sequenced from individuals collected from 16 natural populations across its range and modelled current and historical potential habitats of the species. Our data indicated a considerably high level of genetic variation within A. szechenyi and noteworthy asymmetry in historical migration from the east to the west. Moreover, two nuclear genetic groups of populations were revealed, corresponding to the two geographic regions separated by the Tengger Desert. However, analysis of cpDNA data did not show significant geographic structure. The most plausible explanation for the discrepancy between our findings based on cpDNA and nDNA data is that A. szechenyi populations experienced long periods of geographic isolation followed by range expansion, which would have promoted generalized recombination of the nuclear genome. Our findings further highlight the important role that the Tengger Desert, together with the Helan Mountains, has played in the evolution of desert plants and the preservation of biodiversity in arid Northwest China.

Key words: Asymmetric gene flow, Cytonuclear discordance, Desert growth, Intraspecific divergence