Cymbidium (Orchidaceae: Epidendroideae), with approximately 60 species, is widely-distributed across Southeast Asia, providing a nice system for studying the processes that underlie patterns of biodiversity in the region. However, its biogeographical history remains unclear because phylogenetic relationships of Cymbidium have not been well resolved. Currently, a satisfactory evolutionary framework for studying the factors driving the transition from epiphytism to terrestrialism in Cymbidium is lacking.
In a study published in Plant Diversity, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and Kunming Institute of Botany (KIB) investigated the phylogeny, diversity and biogeography of Cymbidium (Orchidaceae). They sought to provide a robust phylogeny to serve as the basis for understanding the evolutionary history and inferring the underlying drivers of the rich biodiversity of Cymbidium.
The researchers constructed a robust and relatively comprehensive plastome-based phylogeny of 56 Cymbidium species, covering all recognized sections and including around 90% of known species, with four well-resolved major clades.
Through molecular dating and biogeographical analyses, the researchers found that Cymbidium may have originated spanning northern Indo-Burma to the eastern Himalayas during the early Miocene ( about 21.10 million years ago) and rapidly diverged into four major clades during the mid-Miocene. The transition of Cymbidium to neighbouring areas (Borneo, Philippines and Sulawesi) mainly occurred during the Pliocene–Pleistocene.
Moreover, they found that the net diversification rate of Cymbidium has decreased since its origin and was positively correlated with changes in temperature and monsoon intensity. The diversification of Cymbidium coincided with monsoonal intensification in the early Miocene, while global cooling since the middle Miocene may have contributed to a steadily decreasing net diversification rate. The transition in habits may have enabled adaptation to cooler environments and colonization of northern niches.
"Our study suggests that monsoon activity and temperature change have important effects on plant diversification dynamics in Southeast Asia,” said YU Wenbin of XTBG.
Contact
YU Wenbin Ph.D Principal Investigator
Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China
E-mail: yuwenbin@xtbg.ac.cn
First published: 12 March 2024
