A recent study published in Science Advances has shed light on the evolutionary forces that have shaped alpine biodiversity over the past 30 million years. Conducted by researchers from the Xishuangbanna Tropical Botanical Garden of the Chinese Academy of Sciences, along with international collaborators, the research highlights the significant roles of mountain building and climate cooling in driving plant diversity across five major mountain systems in the Northern Hemisphere.
The research team utilized phylogenetic analyses combined with geological context and paleoclimate reconstructions. This comprehensive approach allowed them to map the evolutionary history of 34 groups of flowering plants, encompassing 8,456 species. By examining how these plants spread and diversified over time, the researchers were able to connect the influences of geological uplift and climate change on the alpine flora.
Key Findings on Plant Evolution
Xing Yaowu, a co-corresponding author of the study, stated, “Our work links plant evolution with Earth’s geological and climate history, showing how ancient mountains and climate changes have shaped alpine life in clear, predictable ways.” The findings indicate that both mountain uplift and cooler global temperatures were essential for the expansion and diversification of alpine plant groups, regardless of their origin.
For instance, the formation of rising mountains created new habitats conducive to species evolution. Simultaneously, cooling climates facilitated the connection of previously isolated mountain regions, allowing for greater plant dispersal and interaction across mountain ranges.
The study also revealed that different mountain systems exhibit unique evolutionary mechanisms. For example, the Tibeto-Himalayan-Hengduan (THH) region served as a “cradle” for biodiversity, with over half of new species arising through in-situ diversification. In contrast, European and Irano-Turanian alpine floras were predominantly formed from local mid- to low-elevation lineages adapting to alpine environments. The Tianshan Mountains, on the other hand, primarily “imported” species from the THH region.
Implications for Global Biodiversity
The researchers discovered that active mountain uplift consistently accelerates the formation of new plant species within the same geographical area. This finding underscores the profound influence of geological processes on biodiversity.
According to Wen-Na Ding, the first author of the study, “These asynchronous yet predictable assembly dynamics help explain why alpine plant communities differ so much from one region to another today.” The study further indicates that over the last five million years, global cooling intensified connections between cold Arctic and alpine habitats, effectively transforming the boreal-arctic region into a “biogeographic crossroads” for floristic exchange between Eurasia and North America.
Overall, this research provides valuable insights into the factors contributing to the exceptional biodiversity found in mountain regions. The findings not only enhance our understanding of plant evolution but also illustrate the complex interplay between geological and climatic factors in shaping life on Earth.
More information can be found in the study titled, “The asynchronous rise of Northern Hemisphere alpine floras reveals general responses of biotic assembly to orogeny and climate change,” available in Science Advances, DOI: 10.1126/sciadv.adz1888.
