ECR Feature: Yun Liu on the influence of elevation on bioregionalisation

Yun Liu is a PhD student at the Chinese Academy of Science’s Institute of Botany. She has a keen interest in phylogeography, specifically in plants. Yun shares her recent work on the incorporation of elevation into bioregionalisation classifications of the Sino-Himalaya flora.

Yun Liu

Name. Yun Liu

Personal links. ResearchGate

Institute. Institute of Botany, Chinese Academy of Sciences

Academic life stage. PhD student

Major research themes. Phylogeny, bioregionalisation, phylofloristics, biogeography

Current study system. Currently, my major research focus is on the spatial and temporal evolution of the Sino-Himalayan flora. The Sino-Himalaya is one of the most biodiverse mountain regions on Earth, harbouring a complex diversity of floristic elements and various endemic and endangered species. The biodiversity of the Sino-Himalaya bears the signature of deep-time evolutionary and ecological processes, a history well worth preserving, especially against habitat destruction and climate change. However, the origin and evolution of the unique biota is poorly understood, even though this information is crucial to enhance our understanding of the evolution of mountain biodiversity. Exploring the evolutionary history of the Sino-Himalayan flora is a cool but challenging task.

Representative plant groups in the Sino-Himalayan flora. (A) Allium yuanum (B) Pedicularis mussoti (C) Meconopsis speciosa (D) Saussurea obvallata (E) Aconitum flavum (F) Saussurea inversa (G) Primula sinensis (H) Rhododendron chamaethomsonii (I) Gentiana arethusae var. delicatula. The photos of A, B, C, G, H, and I were taken by Jianfei Ye; the photos of D, E, F were taken by Ze Wei.

Recent publication in JBI. Liu, Y., Ye, J. F., Hu, H. H., Peng, D. X., Zhao, L. N., Lu, L. M., … & Chen, Z. D. Influence of elevation on bioregionalisation: A case study of the Sino-Himalayan flora. Journal of Biogeography. (Link here)

Motivation behind this work. Our work on the Sino-Himalayan flora focuses on its bioregionalisation, that is the classification of biota into hierarchical biogeographical areas (e.g. kingdoms, regions, subregions) according to the spatial distribution of taxa (e.g. families, genera, species). In recent years, significant progress has been made in the field of bioregionalisation by incorporating evolutionary information from phylogenetic trees, instead of solely emphasising the importance of endemic taxa or using taxonomic dissimilarity. However, only a few studies have considered the effect of vertical gradients (elevation) on the bioregionalisation of montane regions. The complex topography and large elevational gradients in the Sino-Himalayan area provide an ideal system to test the influence of elevation on bioregionalisation.

The Hengduan Mountains with a broad elevational range and Faxon fir, Abies fargesii var. faxoniana (Rehder & E. H. Wilson) Tang S. Liu, forest in the Kangding county, western Sichuan, China. Photograph by Jianfei Ye.

Methods. We compiled distribution data and elevation ranges of angiosperms in the Sino-Himalaya and adjacent areas and reconstructed a species-level phylogenetic tree of 19,313 angiosperm species. The area was divided into 398 grid cells, each 1×1°. Nine datasets of different elevation ranges were then used to delineate the flora of the Sino-Himalaya and adjacent areas using the phylogenetic dissimilarity approach.
Although several studies have considered the effect of elevation on the bioregionalisation of montane regions, no study has provided adequate methodological detail to incorporate elevation data into the bioregionalisation of areas with broad elevational gradients. In this study, we built a regionalisation scheme of the Sino-Himalayan flora by combining phylogenetic and elevation data.

Major results. Our study of bioregionalisation in montane regions has moved from a two-dimensional (latitude and longitude) to a three-dimensional (latitude, longitude, and elevation) perspective. It provides novel insights into the regionalisation of the Sino-Himalayan flora and highlights the importance of incorporating elevation data in the bioregionalisation of mountainous areas. The integration of elevation helped to identify boundaries of finer biogeographical units (regions and/or subregions) within the flora. By incorporating both elevational and phylogenetic information, we were able to identify eight distinct subregions nested within the Yunnan Plateau, Hengduan Mountains, and East Himalaya regions in the Sino-Himalaya area. The bioregionalisation scheme helps us to understand the origin and evolution of the Sino-Himalayan flora and explore the spatial and temporal distribution patterns of biodiversity. It provides basic units for broad-scale ecological and evolutionary studies and spatially explicit frameworks for making conservation planning.

Complex topography of the giant Galongla Mountain in Bomê County, Xizang. Photograph by Jianfei Ye.

Unexpected challenges. One challenge was the reconstruction of a species-level phylogenetic tree of 19,313 angiosperm species. We had to align sequences and then manually adjust them to fit homology criteria. This process was very time consuming and required a lot of patience. To study the effects of elevation on bioregionalisation, we used segmentation analysis to obtain sub-datasets of different elevation gradients. We divided the elevation range of species, extracted species from each elevation range, and then compared regionalisation results based on datasets of different elevation ranges to reveal the influence of elevation on bioregionalisation.

Next steps. Our regionalisation scheme of the Sino-Himalayan flora revealed the distribution patterns of biodiversity and provided us a spatially explicit framework for the future research. Therefore, the next step is to focus on the evolutionary history of the Sino-Himalayan flora. The Sino-Himalayan flora is composed of complex floristic elements from various floras and harbours many endemic and endangered species. It is fascinating for us to explore when and how the exceptionally species-rich and unique flora formed over geological time.

Yun (pictured in center) out in the field with her colleagues in the Gansu province, China.

If you could study any organism on Earth, what would it be? Plants are my passion. Plants make our living world colourful and form the backbone of terrestrial ecosystems and the base of food chains. They also serve as the material basis for human survival by providing oxygen, food, medicines, biofuels, building materials and other products. We can’t live without plants. But aside from their importance to ecosystem function, I find plants so incredibly beautiful, and they harbour so much diversity that I could spend a lifetime studying.

Anything else to share? Fieldwork is an interesting thing. When you are not in a state to write your paper or come up with a new idea to study, take a walk in the wild and enjoy the beauty and mystery of nature.

Published by jbiogeography

Contributing to the growth and societal relevance of the discipline of biogeography through dissemination of biogeographical research.

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