Plant Evolves To Resemble Rocky Debris To Become Less Visible To Humans

Fritillaria delavayi is a perennial herb with 3 or 5 leaves – varying in color from grey to brown to green – closely arranged along the stem, native to China’s Hengduan mountains. The species ccolonizes rocky slopes, sandy and gravelly places higher than 11,000 feet (or 3.400 m) above sea level. As the leaves die off at the end of the short summer in the mountains, the plant survives the long winter by developing an underground bulb. After five years, the plant produces a single yellow flower.

In a paper published in the journal Current Biology, an international team of botanists describe a curious case of natural selection of this species driven by humans. In the study, the researchers measured how closely plants from different populations of Fritillaria delavayi match their mountain environment and how easy they were to collect, and spoke to local people to estimate how much harvesting took place in each location.

The superficial visible parts of the plant are poisonous and large herbivors native to the region, like wild sheep and goats, avoid eating them. However, the bulb of the species has been used in Chinese medicine for more than 2,000 years, and high prices in recent years have led to increased harvesting.

On hard to access sites rarely visited by collectors, the plant possesses green leaves and displays the common yellow flower of naturally occurring populations. On sites frequently visited by collectors, the entire plant resembles the color of the surrounding rocky underground. In many cases, the camouflage is perfect, the leaves of the plant matching the color and texture of shards of schist, a slate-like metamorphic rock common in the area.

The camouflaged individuals are more likely to avoid being spotted and collected by humans, and over time will produce more offsprings with similar properties.

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