A new study published on December 19, 2025, in *Science Advances* has revealed significant insights into how mountain building and climate change over the past 30 million years have influenced biodiversity in alpine regions. Researchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences, in collaboration with international partners, conducted an extensive analysis of five major mountain systems in the Northern Hemisphere.
The research aims to clarify the processes that have led to the exceptional plant diversity found in alpine biomes. Mountainous areas are known to host a noteworthy proportion of the world’s plant species, yet the mechanisms behind this diversity have not been clearly understood until now. By combining phylogenetic analyses with geological context and paleoclimate reconstructions, the team was able to identify the roles played by both mountain formation and climatic shifts in the evolutionary history of alpine flora.
The study examined the evolutionary trajectories of 34 groups of flowering plants, encompassing a total of 8,456 species. By reconstructing the historical spread and diversification of these plants across various mountain ranges, the researchers mapped how gradual climate cooling expanded cold habitats over millions of years, ultimately connecting previously isolated high-altitude regions.
Key Findings on Plant Evolution
According to Xing Yaowu, co-corresponding author of the study, “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 the expansion and diversification of alpine plant groups were driven by the dual forces of mountain uplift and cooler global temperatures, irrespective of the geographical origins of these plant groups.
Rising mountains not only created new habitats for plants to evolve but also facilitated the mixing of species across mountain ranges as climates cooled. Different mountain systems demonstrated distinct evolutionary mechanisms. For instance, the Tibeto-Himalayan-Hengduan (THH) region acted as a “cradle” for new species, with over half arising from in-situ diversification. In contrast, European and Irano-Turanian alpine floras mainly developed from local mid- to low-elevation lineages adapting to alpine conditions. The Tianshan Mountains, on the other hand, primarily “imported” species from the THH region.
Across all regions studied, active mountain uplift consistently accelerated the formation of new plant species within the same geographical area. This underscores the significant role geological processes play in shaping biodiversity.
Implications for Global Biodiversity
The research highlights that these asynchronous yet predictable assembly dynamics contribute to the considerable differences observed in alpine plant communities across various regions today. Over the last five million years, intensified global cooling has further enhanced connections between cold Arctic and alpine habitats, transforming the boreal-arctic region into a “biogeographic crossroads” for floristic exchange between Eurasia and North America.
These findings present a coherent explanation for the remarkably high biodiversity found in mountain regions. As noted by Ding Wenna, first author of the study, the research clarifies how both geological and climatic factors have historically shaped the distribution and diversity of alpine plant life.
The study, titled “The asynchronous rise of Northern Hemisphere alpine floras reveals general responses of biotic assembly to orogeny and climate change,” provides critical insights into the complex interplay between climate, geology, and biodiversity, emphasizing the importance of understanding these dynamics in the face of ongoing climate change.
For further details, the article can be accessed in *Science Advances* (DOI: 10.1126/sciadv.adz1888).
