Why is biodiversity important?

When most people think of biodiversity, they think of verdant Amazonian rainforests or vibrant coral reefs in tropical seas. But even a typical house in the suburbs teems with an amazing diversity of life. Spiders, insects and other arthropods crawl in nooks and crannies. Molds, algae and fungi bloom on our foods and in our showers. Grasses and weeds grow in the front yard. And birds and mammals camp out in our attics, eaves and chimneys.

In the home, however, many of us consider that diversity a bad thing and combat it with insecticides, household cleaners, weed killers and exterminators. On a global scale, however, biological diversity -- or biodiversity -- is vitally important to the health of our planet and humanity.

To understand why biodiversity is important, we have to think like biologists. Unlike nonscientists, biologists don't think of biodiversity strictly in terms of the number of species found on Earth. In fact, the variety of living things found across the planet -- also known as species diversity or species richness -- is just one part of biodiversity. Genetic diversity, which refers to genetic variation within and between populations, has a big role, too. For example, think about bald eagles in North America. Most bald eagles live in Alaska and British Columbia. Another large population lives in the Gulf States, from Texas and Baja California across to South Carolina and Florida. The number of genes -- discrete units of hereditary information consisting of unique DNA code -- found within all North American bald eagles represents their total genetic diversity.

Our eagle example also demonstrates another aspect of diversity. The Pacific Northwest represents a unique ecosystem. The Gulf Coast of Florida is another unique ecosystem with different characteristics. Having a rich variety of ecosystems, what biologists call ecosystem diversity, constitutes another important level of biodiversity.

Preserving biodiversity at any level may not seem like a big deal -- at first. After all, scientists have described and named nearly 2 million species of organisms. They think 10 million species or more exist on Earth, but haven't been discovered [source: Campbell]. What's the loss of a few species here and there? Well, according to evolutionary biologist E. O. Wilson, species loss may go against biophilia, or the tendency of humans to focus on life and lifelike processes. If this is true, then contributing to the destruction of living things goes against what it means to be human. It also reinforces the notion that we shouldn't deprive future generations of the same diversity of life we enjoy today.

That's the moral argument. We'll tackle the practical side of biodiversity next.