Why is biodiversity important?

This cute cheetah cub could benefit from a bit more diversity. Serious inbreeding has decreased the gene pool of wild cheetahs and increased their vulnerability to changes in the environment. See more pictures of big cats.
Tom Brakefield/Stockbyte/Thinkstock

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.

From Genes to Jeans: The Benefits of Biodiversity

Maintaining biodiversity comes with a few practical benefits. When a species exhibits great genetic diversity, it has a larger pool of genes available to it. Having more genes makes the species better equipped to respond to changing conditions.

Take cheetahs, for instance. About 10,000 years ago, all but one species of cheetah became extinct, leaving just Acinonyx jubatus in Africa. This population of animals was relatively small, which forced closely related individuals to mate with each other. Over the years, inbreeding eliminated all of the genetic diversity from wild cheetahs, leaving them vulnerable to sudden changes in their environment, such as the introduction of a new virus.

Humans, too, benefit from genetic diversity, but we also rely heavily on the great variety of organisms that share the planet with us. Plants, animals, bacteria and fungi provide raw materials for human use. We base our diets on food crops and the animals that eat them. We clothe ourselves using material derived from plant and animal fibers. We take advantage of single-celled organisms, from bacteria to yeast, to drive important industrial and manufacturing processes.

And then there's medicine. Almost 40 percent of all prescription drugs sold worldwide contain natural compounds found in different plant, animal and fungal species [source: USAID]. Penicillin stands as a classic example of how mankind has benefitted from a drug obtained from another organism.

Perhaps the biggest benefit of biodiversity isn't what compounds an individual species carries in its cells, but how that species fits together and interacts with other species in its ecosystem and how that ecosystem works with others across the world.

Take pollination as an example. Plants rely on pollinators -- birds, mammals and insects -- to help transfer pollen and, ultimately, to create seeds and fruit. Honeybees are an important pollinator, particularly for specialty food crops. Unfortunately, in 2006, some beekeepers began reporting losses of up to 90 percent of their hives [source: Kaplan]. Scientists now refer to this as colony collapse disorder, and they worry that crop production in the United States could suffer significantly.

Pollination is just one service provided by the complex interplay of living things. Ecosystem services also purify water, generate fertile soil, break down wastes, help control pests and moderate weather extremes. Human activity has taken a toll on all of these processes and will continue to do so as the global population swells from 6 billion to 9 billion people by 2050 [source: Secretariat of the Convention on Biological Diversity]. It's a sobering thought, even to those of us learning about biodiversity in our suburban backyards.

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