A highly sought after plant used in traditional Chinese medicine has evolved camouflage to make itself harder for humans to spot and collect, reports Jonathan Lambert for Science News.
The plant, Fritillaria delavayi, grows on the rocky alpine slopes of China’s Hengduan Mountains, and for more than 2,000 years its dried bulbs have been used to treat heart and lung ailments. Historically, the plant was not hard to find—a bright sprig of green amid a sea of gray scree—but demand for the powder made from its bulbs has made it rarer and more expensive. A kilogram of the powder now costs $480 ($218 per pound), and requires harvesting more than 3,500 individual plants, which only begin to flower in their fifth season, according to Science News.
But just as many animals have evolved camouflage to better evade predators, human harvesting behaviors have spurred many Fritillaria plants to shift from loud greens to the muted grays and browns of the rocks they grow between, the researchers report in a study published this week in the journal Current Biology. The researchers also found that this effect is especially pronounced in areas where the plants are most heavily pursued by people looking to pluck them, reports Patrick Barkham for the Guardian.
“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,” says Yang Niu, a botanist at the Kunming Institute of Botany and co-author of the study, in a statement. “Then we realized humans could be the reason.”
For the study, researchers used an instrument called a spectrometer to measure how closely the color of the plants matched their environment, according to the statement. They also used records kept at seven locations that tallied the annual weight of bulbs harvested from 2014 to 2019, per Science News. This data allowed the researchers to assess how heavily Fritillaria was being harvested in each area.
When the team cross referenced the locations of the most intense harvesting and the plants with the best camouflage a pattern emerged. The sites where the most Fritillaria plants had been harvested were also the places where the plant’s coloration mimicked its backdrop most convincingly.
“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,” says Martin Stevens, an ecologist at the University of Exeter and co-author of the study, in the statement. “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. It’s possible that humans have driven evolution of defensive strategies in other plant species, but surprisingly little research has examined this.”
Per the Guardian, the researchers also conducted a computer-based experiment where participants tried to find the plants in photographs. Understandably, people had a harder time picking out the plants with coloration more closely matched to their surroundings, suggesting that the camouflage was indeed an effective way of evading humans.
The new paper “is quite convincing,” Julien Renoult, an evolutionary biologist at the French National Centre for Scientific Research who was not involved in the research, tells Science News. “It’s a nice first step toward demonstrating that humans seem to be driving the very rapid evolution of camouflage in this species.”