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

• Published in: Journal of systematics and evolution : JSE Vol. 59; no. 3; pp. 419 - 428
• Main Authors: Low, Shook Ling, Yu, Chih‐Chieh, Ooi, Im Hin, Eiadthong, Wichan, Galloway, Alan, Zhou, Zhe‐Kun, Xing, Yao‐Wu
• Format: Journal Article
• Language: English
• Published: Beijing Wiley Subscription Services, Inc 01.05.2021
• Subjects: Araceae; Asian monsoon; Biodiversity; biodiversity hotspots; Biogeography; Endemic species; Flora; floristic region; Miocene; Monsoons; Old World tropic; peripatric speciation; Phylogeny; Seasonal variations; Speciation; Indochina
• ISSN: 1674-4918; 1759-6831
• DOI: 10.1111/jse.12689

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 aimed to investigate the biogeographic origin of the Asian paleotropical flora by tracking the speciation and diversification history of a typical tropical perennial, Typhonium sensu stricto (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 epoch, ca. 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. has 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. Typhonium s.s. originated in Indochina during the early–middle Miocene, ca. 17.24 Ma. Most of the in situ diversification within the genus Typhonium s.s. has 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 epoch. Peripatric speciation might have played an essential role in the diversification process of widely disseminated species.