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"No man is an island,
entire of itself; every man
is a piece of the Continent,
a part of the main."
—John Donne
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Excerpted from Endangered Species
Preserving
Biodiversity
Is Important
by Katie de Koster
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 The poet John Donne wrote, "No man is an island, entire of itself; every man is a piece of the Continent, a part of the main."
In terms of biodiversity (also called biological diversity), no living organism is an island. All life on earth is bound together in one  interdependent system. Biodiversity refers not only to every plant, animal, and microorganism, but also, on smaller and larger scales, to their genes and to the ecosystems they form. When an individual species decreases or becomes extinct, the loss may be felt on all three levels.
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Genetic Contributions
The Pacific yew is a bushy tree that grows in the shadows of Douglas firs in the old-growth forests of the Pacific Northwest. To loggers and the U.S. Forest Service, the yew was a weed, a "trash" tree. When the firs were harvested as timber, yews in the same area were often slashed and burned.
Then a study sponsored by the National Cancer Institute found a compound in the yew’s bark, taxol, that helps cure various types of cancer. It took the bark from three thousand trees to make one kilogram of taxol, and soon the "trash" trees were being destroyed by poachers who stole their valuable bark. Fortunately, a way to synthesize taxol was discovered, but the drug itself would never have been found if the Pacific yew had become extinct.
Similarly, in 1960 a victim of childhood leukemia had only a 20 percent chance to survive. Today, thanks to medicine derived from an obscure plant, the rosy periwinkle, the odds are reversed: treated children have an 80 percent chance of survival.
NASA scientist Anthony C. Janetos notes that these discoveries are not isolated phenomena: "Four out of every five of the top 150 prescription drugs used in the U.S. have had their origins in natural compounds."1. . .
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From "Preserving Biodiversity Is Important" and "It Is Not Necessary to Preserve All Species" from Endangered Species by Katie de Koster. Copyright © 1998 by Greenhaven Press, Inc. Reprinted by permission of The Gale Group.
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