Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (1): 1-11.DOI: 10.3773/j.issn.1005-264x.2009.01.001

• Research Articles •     Next Articles

MATERNAL DIVERGENCE AND PHYLOGEOGRAPHICAL RELATIONSHIPS BETWEEN HIPPOPHAE GYANTSENSIS AND H. RHAMNOIDES SUBSP. YUNNANENSIS

CHENG Kai1,2, SUN Kun3, WEN Hong-Yan4, ZHANG Min1, JIA Dong-Rui2, LIU Jian-Quan2,*()   

  1. 1College of Agriculture, Sichuan Agricultural University, Ya’an, Sichuan 625014, China
    2MOE Key Laboratory of Arid and Grassland Ecology, School of Life College, Lanzhou University, Lanzhou 730000, China
    3College of Life Sciences, Northwest Normal University, Lanzhou 730070, China
    4Management Office of Utilization and Innovation of Biological Resources, Lijiang, Yunnan 674100, China
  • Received:2007-12-06 Accepted:2008-03-04 Online:2007-12-06 Published:2009-01-30
  • Contact: LIU Jian-Quan

Abstract:

Aims In order to understand complex speciation, it is critically important to investigate the corresponding genetic divergence and lineage sorting between close species or taxa distributed in parapatric regions. Our aim was to outline the distribution of the maternally inherited chloroplast haplotypes of Hippophae gyantsensis and H. rhamnoides subsp. yunnanensis and construct their phylogeographic relationships. The former species occurs in central and west Tibet, while the latter is distributed in northwest Yunnan and west Sichuan. These taxa are distinguished by leaf shape, trichomes and fruits.
Methods We sequenced trnL-F and trnS-G DNA fragments for 109 trees of 14 populations from these two taxa.
Important findings A total of 11 chlorotypes were identified, seven in H. gyantsensis and six in H. rhamnoides subsp. yunnanensis, with two shared. Phylogenetic and Nested Clade Analysis analyses further suggested that the divergence of these haplotypes is highly inconsistent with morphological differentiation of the two taxa, suggesting complex maternal lineage sorting between them. These findings refute the previous systematic placements of H. gyantsensis within the genus. However, the available data could not distinguish between two alterative hypotheses regarding origin of this species: homoploid hybrid versus allopatric speciation. In addition, the unique haplotypes recovered in separate populations within each of two taxa suggest that multiple refugia might have maintained both across their distributional ranges during the Last Glacial Maximum.

Key words: Hippophae rhamnoides subsp. yunnanensis, H. gyantsensis, cpDNA, trnL-F, trnS-G, lineage sorting, speciation, glacial refugia