Understanding the formation of Mediterranean–African–Asian disjunctions: evidence for Miocene climate-driven vicariance and recent long-distance dispersal in the Tertiary relict Smilax aspera (Smilacaceae)

Authors

  • Chen Chen,

    1. Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, China
    2. Laboratory of Systematic & Evolutionary Botany and Biodiversity, Institute of Plant Sciences, and Conservation Center for Gene Resources of Endangered Wildlife, Zhejiang University, Hangzhou, China
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    • These authors contributed equally to this work.
  • Zhe-Chen Qi,

    1. Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, China
    2. Laboratory of Systematic & Evolutionary Botany and Biodiversity, Institute of Plant Sciences, and Conservation Center for Gene Resources of Endangered Wildlife, Zhejiang University, Hangzhou, China
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    • These authors contributed equally to this work.
  • Xi-Hui Xu,

    1. Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, China
    2. Laboratory of Systematic & Evolutionary Botany and Biodiversity, Institute of Plant Sciences, and Conservation Center for Gene Resources of Endangered Wildlife, Zhejiang University, Hangzhou, China
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    • These authors contributed equally to this work.
  • Hans Peter Comes,

    1. Department of Organismic Biology, Salzburg University, Salzburg, Austria
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  • Marcus A. Koch,

    1. Department of Biodiversity and Plant Systematics and Botanical Garden and Herbarium Heidelberg (HEID), Center for Organismal Studies (COS) Heidelberg, Heidelberg University, Heidelberg, Germany
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  • Xin-Jie Jin,

    1. Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, China
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  • Cheng-Xin Fu,

    Corresponding author
    1. Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, China
    2. Laboratory of Systematic & Evolutionary Botany and Biodiversity, Institute of Plant Sciences, and Conservation Center for Gene Resources of Endangered Wildlife, Zhejiang University, Hangzhou, China
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  • Ying-Xiong Qiu

    Corresponding author
    1. Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, China
    2. Laboratory of Systematic & Evolutionary Botany and Biodiversity, Institute of Plant Sciences, and Conservation Center for Gene Resources of Endangered Wildlife, Zhejiang University, Hangzhou, China
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Summary

  • Tethyan plant disjunctions, including Mediterranean–African–Asian disjunctions, are thought to be vicariant, but their temporal origin and underlying causes remain largely unknown. To address this issue, we reconstructed the evolutionary history of Smilax aspera, a hypothesized component of the European Tertiary laurel forest flora.
  • Thirty-eight populations and herbarium specimens representing 57 locations across the species range were sequenced at seven plastid regions and the nuclear ribosomal internal transcribed spacer region. Time-calibrated phylogenetic and phylogeographic inferences were used to trace ancestral areas and biogeographical events.
  • The deep intraspecific split between Mediterranean and African–Asian lineages is attributable to range fragmentation of a southern Tethyan ancestor, as colder and more arid climates developed shortly after the mid-Miocene. In the Mediterranean, climate-induced vicariance has shaped regional population structure since the Late Miocene/Early Pliocene. At around the same time, East African and South Asian lineages split by vicariance, with one shared haplotype reflecting long-distance dispersal.
  • Our results support the idea that geographic range formation and divergence of Tertiary relict species are more or less gradual (mostly vicariant) processes over long time spans, rather than point events in history. They also highlight the importance of the Mediterranean Basin as a centre of intraspecific divergence for Tertiary relict plants.

Ancillary