A new study has found that commercial harvesting by humans is driving the evolution of camouflage in a medicinal species of plant in China.
Called Fritillaria delavayi, the plants grow on the rocky slopes of the Hengduan Mountains in China, and have been used in Chinese medicine for over 2,000 years now to treat lung conditions like asthma, bronchitis, and tuberculosis. After its fifth year, the perennial plant produces a bright yellow-green flower. Reports suggest that in recent years, demand for the plant has risen.
“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,” Yang Niu, who studies plant diversity and biogeography at the Kunming Institute of Botany in India, and was the lead author of the study, said in the press release.
Published in Current Biology, the study by researchers from China and the UK analyzed the degrees to which different populations of the plant matched their surrounding mountainous environments, and also spoke to locals to estimate how much harvesting took place in each of the locations where the plant grew. The results suggested that the level of camouflage in the plants correlated with the harvesting levels in the regions they grew in.
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“Commercial harvesting is a much stronger selection pressure than many pressures in nature. The current biodiversity status on the earth is shaped by both nature and by ourselves,” Hang Sun, Niu’s colleague from the university, who was also involved in the study, told AZoLifeSciences.
The flower of the species has continued to retain its original bright yellow-green color in areas less frequented by collectors. But in areas where they are harvested heavily, the entire plant has begun resembling the rocky background it grows in — with both its leaves and the flower matching shades of slate to be less visible to collectors. And through a computer-based experiment involving the locals, the researchers found that it actually did take them longer to detect the camouflaged plants.
“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… 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, from the Centre for Ecology and Conservation at the University of Exeter, who was also involved in the study, commented.
But is this the only species that has been forced to evolve in response to growing demands by humans? The researchers aren’t sure yet. “It’s possible that humans have driven evolution of defensive strategies in other plant species, but surprisingly little research has examined this,” Professor Stevens noted.
