Popularity of plant is affecting its evolution, study finds

When Charles Darwin explained evolution, the process he observed was natural selection. But two St. Louis-area researchers have found that inadvertent human selection can also cause species to evolve.

Take the case of the snow lotus, a rare fuzzy-ball plant that grows only at high altitudes - 13,000 feet or more - in the Himalayas in Tibet and Yunan province of China.

Researchers Jan Salick, a curator at the Missouri Botanical Garden, and Wayne Law, a graduate student in biology at Washington University, have discovered that one species of the plant has been shrinking over time - the one people like to pick.

The plant is becoming increasingly popular with tourists. It "has a panda bear quality. People recognize it. It is well known," Salick said.

Residents living near the plants pick the largest ones in their only flowering period.

The result is that only smaller, unpicked plants go to seed.

"Selection caused by humans is a powerful force, whether conscious or unconscious, artificial or natural," Salick and Law commented in a paper in today's issue of Proceedings of the National Academy of Sciences.

They report that the heavily harvested snow lotuses have been getting shorter over the last century, while those in areas not picked have not shrunk. And, they noted, a second species, S. medusa, which is not often picked, has not been changing.

"Paradoxically, with unconscious human selection, when a species possesses a certain trait that is valued by people, individuals with that trait will be preferentially harvested and this selection will leave individuals with less desirable traits," Law and Salick pointed out.

The Chinese government and the Nature Conservancy are trying to preserve the plant, Salick said. They want to persuade harvesters of the plant to wait until the plant spreads its seeds before picking them. They want to keep the market for the plant local. "Tibetan doctors don't need that much," she said.

•	Popularity of plant is affecting its evolution, study finds Associated Press, Tuesday, July 5, 2005 Byline: Randolph E. Schmid, Associated Press

•	The Case of the Shrinking Lotus The New York Times, Tuesday, July 5, 2005 Byline: James Gorman