Plant Diversity ›› 2023, Vol. 45 ›› Issue (02): 156-168.DOI: 10.1016/j.pld.2022.10.003

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Wind-dispersed seeds blur phylogeographic breaks: The complex evolutionary history of Populus lasiocarpa around the Sichuan Basin

Xue Lia, Markus Ruhsamb, Yi Wanga, Hong-Ying Zhanga, Xiao-Yan Fana, Lei Zhanga, Jing Wanga, Kang-Shan Maoa   

  1. a. Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, Sichuan, PR China;
    b. Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh EH3 5LR, UK
  • Received:2022-07-22 Revised:2022-10-10 Online:2023-03-25 Published:2023-06-13
  • Contact: Jing Wang,;Kang-Shan Mao,
  • Supported by:
    This project was supported by National Natural Science Foundation of China (grants 31971567 and 31622015) and Fundamental Research Funds for the Central Universities (YJ201936, SCU2020D003, SCU2021D006, SCU2022D003).

Abstract: The strength of phylogeographic breaks can vary among species in the same area despite being subject to the same geological and climate history due to differences in biological traits. Several important phylogeographic breaks exist around the Sichuan Basin in Southwest China but few studies have focused on wind-dispersed plants. Here, we investigated the phylogeographic patterns and the evolutionary history of Populus lasiocarpa, a wind-pollinated and wind-dispersed tree species with a circum-Sichuan Basin distribution in southwest China. We sequenced and analyzed three plastid DNA fragments (ptDNA) and eight nuclear microsatellites (nSSRs) of 265 individuals of P.lasiocarpa from 21 populations spanning the entire distribution range. Distribution patterns based on nSSR data revealed that there are three genetic groups in P.lasiocarpa. This is consistent with the three phylogeographic breaks (Sichuan Basin, the Kaiyong Line and the 105°E line), where the Sichuan basin acts as the main barrier to gene flow between western and eastern groups. However, the distribution pattern based on ptDNA haplotypes poorly matched the phylogeographic breaks, and wind-dispersed seeds may be one of the main contributing factors. Species distribution modelling suggested a larger potential distribution in the last glacial maximum with a severe bottleneck during the last interglacial. A DIYABC model also suggested a population contraction and expansion for both western and eastern lineages. These results indicate that biological traits are likely to affect the evolutionary history of plants, and that nuclear molecular markers, which experience higher levels of gene flow, might be better indicators of phylogeographic breaks.

Key words: Phylogeography, Sichuan basin, Populus lasiocarpa, Kaiyong line, Demographic history