J Syst Evol

• Research Articles •    

Extensive Miocene speciation in and out of Indochina: the biogeographic history of Typhonium sensu stricto (Araceae) and its implication for the assembly of Indochina flora

Shook Ling Low1,2, Chih-Chieh Yu1,2, Im Hin Ooi3, Wichan Eiadthong4, Alan Galloway5, Zhe-Kun Zhou1,2,6, Yao-Wu Xing1,2*   

  1. 1CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, Yunnan, China
    2Center of Plant Ecology, Core Botanical Gardens, Chinese Academy of Sciences, Xishuangbanna 666303, Yunnan, China
    3Biodiversity Management Section, Penang Botanic Gardens Department, 10350 Pulau Pinang, Malaysia
    4Department of Forest Biology, Faculty Forestry, Kasetsart University, 50 Ngamwongwan Road, Ladyao subdistrict, Jattujak, Bangkok 10900, Thailand;
    5P.O. Box 37456, Raleigh, NC 27627, USA
    6Key Laboratory for Plant Diversity and Biogeography of East Asia, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650204, China
  • Received:2020-03-25 Accepted:2020-08-31

Abstract: The Asian paleotropical flora is characterized by abundance of endemic species, high biodiversity, and complex geological and climatic histories. However, the main driving mechanism underlying such high tropical biodiversity remains unclear. Hence, the present study aims to investigate the biogeographic origin of the Asian paleotropical flora by tracking the speciation and diversification history of a typical tropical perennial, Typhonium s.s. (Araceae), using a time-calibrated whole-plastome phylogeny. In particular, we tested whether the Asian paleotropic region is a macroevolutionary source or sink. We observed that Typhonium s.s. originated in Indochina during the early-middle Miocene, approximately 17.24 Ma [95% highest posterior density (HPD): 12.83 ̶ 21.99 Ma]. Most of the in situ diversification within the genus Typhonium s.s. have been underway since 14.73 Ma, with an accelerated lineage diversification at ca. 15-17 Ma, which may have been triggered by the intensification of the Asian monsoon system around the middle Miocene. Furthermore, the underground tuberous stem of Typhonium s.s. might have played an essential role in the adaptation to the seasonality caused by the monsoon in Indochina. Our results also suggested that peripatric speciation may be important in the diversification of T. trilobatum and T. roxburghii. This study provides a framework for studies in biogeography and evolution of the Asian paleotropical flora.

Key words: Asian monsoon, biodiversity hotspots, floristic region, Old World Tropic, peripatric speciation