The Hengduan Mountains, located in China, host some of the world's oldest flower lineages - dating back close to 30 million years.
Close to 3,000 alpine plant species, including the Rhododendron (pictured above), are found in the Hengduan Mountains. Yaowu Xing
At first glance, these mountains adjoining the Tibetan Plateau seem similar to other ranges, such as North America's Rocky Mountains. Upon closer examination, they reveal themselves to be home to one of Earth's richest alpine plant communities, consisting of more than 3,000 species.
"It’s a fascinating place, especially botanically...you realize that there are 10 times more species." - Richard Ree, evolutionary biologist at the Field Museum
Published in the journal Science, new research indicates that unique flower groups have been evolving in the area for tens of millions of years. The region's climate, contributing to intense monsoon rains and moisture promoting erosion, has isolated plant populations that ultimately diverge, forming new species.
Richard Ree and Wen-Na Ding, a Ph.D. student at Xishuangbanna Tropical Botanical Garden, discovered this by using DNA sequences from 18 plant groups to create evolutionary trees. Additionally, they calibrated a timeline of the region's geological history using plant fossils. Comparing the two, the duo estimated speciation rates.
Their findings pointed to only one possible result: some of the plant groups originated nearly 30 million years ago in the Hengduan Mountains. Major geological events lead to the specification of the alpine flora. Some 19 million to 17 million years ago, uplift of mountain chains isolated plant populations. About 15 million years ago, monsoons intensified and reshaped the landscape, accelerating specification again.
“Definitely, the monsoon has an enormous role to play," - Adrien Fave, evolutionary biologist at Senckenberg Research Institute and Natural History Museum
Wildflower displays (pictured above) provide a growing incentive for ecotourism in the Hengduan Mountain region. Jian Huang
With an increase in human activity, it is uncertain how the Hengduan's ancient flora will cope. Climate change - in particular - provides an immense threat to the region. Seeing as its plant diversity resulted from ancient geological events, traditional approaches to predict the region's response to global warming won't work, says Carsten Rahbek.
“The foundation of how we do biodiversity forecasting of climate change, especially in mountains, is probably on very shaky ground," - Carsten Rahbek, a macroecologist at the University of Copenhagen
Another pressing issue includes development, primarily the construction of new roads, hydroelectric dams, and growing settlements. However, brilliant wildflower displays each summer have brought ecotourism to the Hengduan Mountains. China's government has taken measures to protect this cradle of the world's oldest flower lineages.