Molecular phylogenetics and biogeography of the eastern Asian–eastern North American disjunct Mitchella and its close relative Damnacanthus (Rubiaceae, Mitchelleae)

Authors

  • Wei-Ping Huang,

    1. Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
    2. University of Chinese Academy of Sciences, Beijing, China
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  • Hang Sun,

    1. Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
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  • Tao Deng,

    1. Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
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  • Sylvain G. Razafimandimbison,

    1. Bergius Foundation, The Royal Swedish Academy of Sciences and Department of Botany, Stockholm University, Stockholm, Sweden
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  • Ze-Long Nie,

    Corresponding author
    • Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
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  • Jun Wen

    Corresponding author
    1. Department of Botany, National Museum of Natural History, MRC 166, Smithsonian Institution, Washington DC,, USA
    • Key Laboratory of Biodiversity and Biogeography, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan, China
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Corresponding authors. E-mail: wenj@si.edu; niezl@mail.kib.ac.cn

Abstract

Mitchella is a small genus of the Rubiaceae with only two species. It is the only herbaceous semishrub of the family showing a disjunct distribution in eastern Asia and eastern North America, extending to Central America. Its phylogeny and biogeographical diversification remain poorly understood. In this study, we conducted phylogenetic and biogeographical analyses for Mitchella and its close relative Damnacanthus based on sequences of the nuclear internal transcribed spacer (ITS) and four plastid markers (rbcL, atpB-rbcL, rps16 and trnL-F). Mitchella is monophyletic, consisting of an eastern Asian M. undulata clade and a New World M. repens clade. Our results also support Michella as the closest relative to the eastern Asian Damnacanthus. The divergence time between the two intercontinental disjunct Mitchella species was dated to 7.73 Mya, with a 95% highest posterior density (HPD) of 3.14−12.53 Mya, using the Bayesian relaxed clock estimation. Ancestral area reconstructions suggest that the genus originated in eastern Asia. The semishrub Mitchella appears to have arisen from its woody ancestor in eastern Asia and then migrated to North America via the Bering land bridge in the late Miocene. © 2013 The Linnean Society of London

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