J Syst Evol ›› 2020, Vol. 58 ›› Issue (2): 159-173.DOI: 10.1111/jse.12490

• Research Articles • Previous Articles     Next Articles

Divergence and hybridization in the desert plant Reaumuria soongarica

Yong Shi1,2, Xia Yan1,3, Heng-Xia Yin1,4, Chao-Ju Qian1, Xing-Ke Fan1,5, Xiao-Yue Yin1,5, Yu-Xiao Chang6, Cheng-Jun Zhang2*, and Xiao-Fei Ma1*   

  1. 1Key Laboratory of Stress Physiology and Ecology in Cold and Arid Regions, Northwest Institute of Eco‐Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
    2Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China
    3Key Laboratory of Eco‐hydrology of Inland River Basin, Northwest Institute of Eco‐Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
    4State Key Laboratory of Plateau Ecology and Agriculture, Qinghai University, Xining 810016, China
    5University of Chinese Academy of Sciences, Beijing 100049, China
    6Agricultural Genomes Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
  • Received:2018-09-29 Accepted:2019-02-25 Online:2019-03-07 Published:2020-03-01


Speciation is widely accepted to be a complex and continuous process. Due to complicated evolutionary histories, desert plants are ideal model systems to understand the process of speciation along a continuum. Here, we elucidate the evolutionary history of Reaumuria soongarica (Pall.) Maxim., a typical desert plant that is wildly distributed across arid central Asia. Based on variation patterns present at nine nuclear loci in 325 individuals (representing 41 populations), we examined the demographic history, patterns of gene flow, and degree of ecological differentiation among wild R. soongarica. Our findings indicate that genetic divergence between the ancient western and eastern lineages of R. soongarica occurred approximately 0.714 Mya, probably due to the Kunlun–Yellow River tectonic movement and the Naynayxungla glaciation. Later, multiple hybridization events between the western and eastern lineages that took place between 0.287 and 0.543 Mya, and which might have been triggered by the asynchronous historical expansion of the western and eastern deserts, contributed to the formation of a hybrid northern lineage. Moreover, despite continuing gene flow into this population from its progenitors, the northern lineage maintained its genetic boundary by ecological differentiation. The northern lineage could be an incipient species, and provides an opportunity to study the continuous process of speciation. This study suggests that two opposite evolutionary forces, divergence and hybridization, coexisting in the continuous speciation of the desert plant R. soongarica in a short time. Moreover, we provide evidence that this continuous speciation process is affected by geological events, climatic change, and ecological differentiation.

Key words: arid central Asia, ecological speciation, glaciation, hybrid speciation, Quaternary, speciation continuum