Species richness is not only spatially heterogeneous along latitude, but also among the hyperdiverse tropical floras. However, there are few studies to clarify the species richness patterns in tropical terrestrial orchids.

In a study published in Molecular Phylogenetics and Evolution, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) and their collaborators tried to reveal the temporal and spatial dynamics of tropical terrestrial orchids, and clarify the main factors of species richness disparity among tropic floras through its evolutionary history.

The researchers reconstructed the phylogenetic relationships and evolutionary history of Collabieae, and combined climate and distribution data to discuss the potential influencing factors of the global species richness disparity among tropical floras.  

The researchers collected 127 species in 21 genera (represented 88% genera and 26% species) of the tribe Collabieae in orchid family, and employed 24 plastid markers and two nuclear regions to reconstruct the most comprehensively sampled phylogenetic tree of Collabieae to date. They also combined climate and distribution data to discuss the potential influencing factors of the global species richness disparity among tropical floras.  

Based on empirical samplings and simulated complete samplings respectively, the researchers further investigated the biogeography, diversification processes and niche evolutionary rates of Collabieae.  

They found that the Collabieae originated on Asia and independently spread to other tropics. Both the net diversification and niche evolutionary rates of Asian lineages were higher than those of African and Oceanian lineages.Precipitation was the principal environmental factor, combined with that Asian lineage has experienced more stable and humid climate, which may contribute to the high diversification rate in Asia of Collabieae. 

“We thus deemed that different net diversification rate is the main driver for species richness disparity, integrated with different colonization times,” said LUO Yan of XTBG. 

Contact 

LUO Yan  Ph.D  

Center for Integrative Conservation, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, Mengla, Yunnan 666303, China                

E-mail: luoyan@xtbg.org.cn   

Available online: 16 June, 2023