Humans have known the bright green flower of Fritillaria delavayi for the last 2,000 years and harvested it for medicinal purposes. Now, it is turning brown in order to camouflage itself from humans.
Fritillaria delavayi has scientists wondering what other plants may have been forced to change their coloring in order to avoid humans. Image credit: Niu et al
Donned with vividly colored petals and evocative scents, many species of flowering plants put a lot of energy into sticking out and attracting the attention of passersby – mostly insects, of course. But for one hillside-growing plant that has long been harvested in China to make traditional medicine, shying away from unwanted attention has proved to be a more effective survival strategy.
A new study published in the journal Current Biology reports that the plant Fritillaria delavayi has evolved to become less visible to humans, suggesting humans are driving the species’ color change as camouflaged plants have a better chance of survival.
The green petals are much easier to spot against the rocks than the brownish ones. Image credit: Niu et al
The plant typically springs a vivid green flower every year after its fifth year of life. Yet the reasearchers found that under the pressure of humans picking the plants for traditional Chinese medicine, certain populations of the plant seem to be gradually losing their bright mature coloring in exchange for a more subtle hue that camouflages against their rocky surroundings.
“Like other camouflaged plants we have studied, we thought the evolution of camouflage of this fritillary had been driven by herbivores, but we didn’t find such animals. Then we realized humans could be the reason,” said Yang Niu, a co-author of the study.
The traditional medicinal plant grows on the hillsides of China’s Hengduan mountains and parts of Tibet. Image credit: Wikimedia Commons
“Many plants seem to use camouflage to hide from herbivores that may eat them – but here we see camouflage evolving in response to human collectors,” Professor Martin Stevens, study author from the Centre for Ecology and Conservation at the University of Exeter in the UK, said in a statement.
“It’s remarkable to see how humans can have such a direct and dramatic impact on the coloration of wild organisms, not just on their survival but on their evolution itself,” he added. “It’s possible that humans have driven evolution of defensive strategies in other plant species, but surprisingly little research has examined this.”
A barely visible Fritillaria delavayi in a population with high harvest pressure. Image credit: Niu et al
According to the new research study conducted by scientists at Kunming Institute of Botany in China and the University of Exeter, the level of camouflage in these plants was tightly correlated with how extensively they were being harvested in the given area.
Found in the rocky hillsides of China’s Hengduan mountains, Fritillaria delavayi is traditionally revered for its supposed ability to treat coughs and other respiratory diseases. Because of these purported medicinal benefits, the plant has been extensively harvested, with recent decades seeing a surge in demand for the plant’s prized bulbs.
Researchers investigated the plant’s shift in coloration by speaking to locals about which areas where the plant grew were most harvested. Then they examined records that counted the annual weight of bulbs harvested in the last five years. A computer-based experiment confirmed that the green-petaled plants were a lot easier to detect by collectors compared to the grey-brown varieties, especially against the rocky background.
The example of this plant shows the subtle ways human activity can impact the evolution of different species. Unfortunately, this mostly means losing our world’s colorfulness, and eventually, even more of those species.