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Interspecific delimitation and phylogenetic origin of Pugionium (Brassicaceae)

Authors

  • Qiu-Shi YU,

    1. (Division of Molecular Ecology, Key Laboratory of Arid and Grassland Ecology, School of Life Science, Lanzhou University, Lanzhou 730000, China)
    2. (Minqin National Studies Station for Desert Steppe Ecosystem, Minqin 733300, China)
    3. (Gansu Desert Control Research Institute, Lanzhou 730070, China)
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  • Qian WANG,

    1. (Division of Molecular Ecology, Key Laboratory of Arid and Grassland Ecology, School of Life Science, Lanzhou University, Lanzhou 730000, China)
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  • Ai-Lan WANG,

    1. (Division of Molecular Ecology, Key Laboratory of Arid and Grassland Ecology, School of Life Science, Lanzhou University, Lanzhou 730000, China)
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  • Gui-Li WU,

    1. (Division of Molecular Ecology, Key Laboratory of Arid and Grassland Ecology, School of Life Science, Lanzhou University, Lanzhou 730000, China)
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  • Jian-Quan LIU

    Corresponding author
    1. (Gansu Desert Control Research Institute, Lanzhou 730070, China)
      Author for correspondence. E-mail: liujq@nwipb.ac.cn; Tel.: 86-931-891-4305; Fax: 86-931-891-4288.
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Author for correspondence. E-mail: liujq@nwipb.ac.cn; Tel.: 86-931-891-4305; Fax: 86-931-891-4288.

Abstract

Abstract Pugionium (Brassicaceae) is a small genus that occurs in central Asian deserts. The interspecific delimitation and taxonomic treatments of this genus are disputed and its phylogenetic origin remains unknown. In the present study, we examined these issues based on morphological and molecular data obtained for the first time. We used statistical methods to examine inter- and intraspecific morphological variations. The results suggest that only two species, namely P. dolabratum and P. cornutum, can be warranted for all examined populations and specimens, whereas three species (P. calcaratum, P. cristatum, and P. pterocarpum) should be incorporated into P. dolabratum. This delimitation was further supported by the molecular data: all populations of P. dolabratum, P. calcaratum, P. cristatum, and P. pterocarpum shared the same internal transcribed spacer genotype, whereas those from P. cornutum had another type. Phylogenetic analyses of Pugionium and representative genera of Brassicaceae based on ndhF sequences suggest that this genus is sister to the genus Megacarpaea, which, together, comprise a well-supported lineage with Farsetia, Lobularia, Iberis, and Ionopsidium, whereas the two other genera that were previously suggested to be closely related to this genus (Isatis and Bunias) were placed in the other lineages. We further discuss the origin of Pugionium and suggest that it probably originated in central Asia when the climate became drier from the late Miocene.

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