 |  Environmental Science: A Global Concern, 7/e William P. Cunningham,
University of Minnesota
Mary Ann Cunningham,
Vassar College
Barbara Woodworth Saigo,
St. Cloud State University
Biodiversity
Be Alert BoxesBE ALERT FOR: Obscure Species
The central message of this chapter, that all sorts of creatures are very important, is not at first intuitively obvious. Oh, you will easily be convinced of the worth of Rauwolfia, blowfly larvae, foxglove, and periwinkle plants, which all produce valuable medicinal products. But there is much more involved than medicines.
Here are some things that complicate our understanding and appreciation of these other values: (1) Many of our benefactors and their actions are so commonplace that they are taken for granted. The incalculable value of the microbes that cause decomposition to complete the material cycles and the free pollination services performed by bees quickly come to mind. We can't even conceive of a world that lacks them. (2) Most of the millions of life forms on earth have simply not been studied. That many will turn out to have special value is a certainty. But no one can say much about what, when, and where. The magnitude of the biological resource is simply not known. (3) Protecting some of the species may necessitate forgoing certain economic activities for ill-defined potential benefits. (4) The value of most is likely to lie not in their worth as individual species but in the collective accomplishments of them all.
BE ALERT FOR: Viable Preserve Size
For a long time, species protection has included setting aside small scraps of land where a rare plant or animal species was found. Ecologists now recognize that many of these communities are too small to be viable over the long term. As a result, the protection focus has shifted to setting aside larger areas in hopes of encompassing intact ecosystems. This seems to be the best way of providing for long-term survival of individual species. Larger preserves also make it more likely that protected populations are large enough to contain broad genetic variability, thus avoiding the founder bottleneck.
BE ALERT FOR: Biodiversity Definition
Biological diversity, often shortened to biodiversity, is a recurrent word in this chapter. Be sure you understand that its meaning has several different aspects.
First, biodiversity refers to the total number of species present. It also includes the notion of a wide range of genetic variation within a species. In other words, biodiversity would be said to have diminished if there were a substantial reduction in the number of individuals present in a species. Biodiversity also refers to the existence of a large variety of types of biological communities. The effort to protect and preserve biodiversity, then, encompasses all three of these elements.
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2003 McGraw-Hill Higher Education