Date: April 28, 2026
Guangzhou, China: South China Botanical Garden researchers uncovered the evolutionary history of Burmannia nepalensis, a fully mycoheterotrophic herb endemic to subtropical evergreen broad-leaved forests. Using plastome sequencing and nuclear microsatellites across 20 populations, the team revealed low within-population genetic diversity but strong genetic differentiation, shaped mainly by geographic isolation and Quaternary climatic fluctuations.
Species distribution modeling indicated stable climatically suitable areas during the Last Glacial Maximum (LGM), supporting multiple glacial refugia in the Nanling Mountains, Wuyi Mountains, and southwestern karst regions. Unlike the classical southward-retreat model, the species persisted in situ in northern refugia without extensive postglacial northward expansion.
Genetic analyses showed that approximately 43% of nuclear variation and 72.11% of plastid variation occurred among populations, indicating limited gene flow restricted by mountain barriers and fragmented habitats. Mantel tests and MMRR analysis confirmed significant isolation-by-distance and isolation-by-instability patterns, with little effect from current environmental differences.
Demographic reconstruction suggested post-LGM population expansion followed by a marked decline around 3,000 years ago. Bottleneck signals were detected in 75% of populations, likely caused by human-induced forest loss and habitat fragmentation rather than recent climate change.
The study highlights the vulnerability of mycoheterotrophic plants, which depend on intact forests and specific fungal symbionts. The findings support the conservation of multiple mountain refugia and emphasize protecting continuous, undisturbed forest habitats to maintain genetic integrity and evolutionary potential.
This work was supported by the National Natural Science Foundation of China, Guangdong Provincial Special Fund for Natural Resource Affairs on Ecology and Forestry Construction, and Guangxi Key Laboratory of Plant Conservation and Restoration Ecology in Karst Terrain. The full study is published in Biological Diversity.
Original Source
Shi, Miaomiao, Tong Zeng, Zhongtao Zhao, et al. 2026. "Historical Climatic Fluctuations and Geographic Isolation Shaped the Phylogeographic Patterns of a Mycoheterotrophic Species in Subtropical China," Biological Diversity: 3(1), 33–46.
https://onlinelibrary.wiley.com/doi/10.1002/bod2.70021
Keywords
Burmannia nepalensis, evergreen broad-leaved forests, glacial refugia, mycoheterotrophs, phylogeography, subtropical China
About the Author
Miaomiao Shi (First Author), PhD, and Assistant Professor, South China Botanical Garden, Chinese Academy of Sciences. Research interests mainly include plant population genetics and evolutionary biology. She has directed 4 projects supported by the National Natural Science Foundation of China and the Natural Science Foundation of Guangdong Province. She has published more than 50 academic papers in journals including Molecular Biology and Evolution, New Phytologist, Journal of Biogeography, and Annals of Botany.
Tieyao Tu (Corresponding Author), Professor and PhD Supervisor, South China Botanical Garden, Chinese Academy of Sciences. He specializes in plant taxonomy and germplasm innovation. He has led 3 NSFC projects and participated in 5 national key programs, including CAS Strategic Priority Projects and the National Key R&D Program. He has edited 4 monographs as chief editor and 3 as associate editor. With more than 70 peer-reviewed papers (30 as first author) published in top journals such as Molecular Biology and Evolution, Taxon, and Molecular Phylogenetics and Evolution, he has also established approximately 50 taxa, including one new tribe and one new genus.
Dianxiang Zhang (Corresponding Author), Professor and Distinguished Expert at the Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, and formerly a Professor and PhD Supervisor at the South China Botanical Garden, Chinese Academy of Sciences. He has long been engaged in research on plant evolutionary ecology and reproductive ecology based on taxonomic and phylogenetic studies. His main research interests include: the ecological and molecular mechanisms underlying the evolution, maintenance, and breakdown of distyly (in taxa such as Primulaceae, Rubiaceae, and Oleaceae), as well as the ecological mechanisms of interactive evolution between mycoheterotrophic plants and mycorrhizal fungi (represented by Burmanniaceae).
About the Journal
Biological Diversity (ISSN: 2994-4139) is a new open-access, high-impact, English-language journal, devoted to advancing biodiversity conservation, enhancing ecosystem services, and promoting the sustainable use of resources under global change. It features innovative research addressing the global biodiversity crisis.
