July 23, 2009

UNIT 8: AnimalsThe Loss of Biodiversity

Extinction is occurring at a rate that is 1000 times faster than any time in the past 100,000 years. Wide swathes of rain forest are being destroyed as humans develop the land for agriculture and other human needs. Because rain forests are areas with high biodiversity, each time an acre of land is lost, species that once lived there may be lost as well. Why is biodiversity important? How does its loss affect you?

Biodiversity at Risk

At present, we are losing more species than we are finding. Across the globe, animal species that are known to be threatened with extinction include

• 12 percent of all birds
• 30 percent of all fishes
• 24 percent of all mammals
• 20 percent of all amphibians

Biologists think that there are least 10 million, and possibly as many as 100 million, species of plants and animals. At current rates of extinction, over half of these species will be gone by the end of this century. Extinction is a natural process and is always occurring. Using evidence from the fossil record, the background extinction rate is calculated to be between 10 and 100 species per year. However, the current rate of extinction greatly exceeds that number. Hundreds of thousands of species will disappear before we are even aware of their existence.

Does Biodiversity Really Matter?

Some people might suggest that biodiversity belongs in a zoo and the rest of the world belongs to humans to develop. Arguments in favor of development include the following:

• The rise and fall of species is part of nature. No species lives forever. New species replace old ones.
• Economic development provides jobs to people who are living in poverty.
• Land set aside as wilderness could be better used as farmland to provide more food for a rapidly increasing human population.

Conservation biologists view the pro-development arguments as shortsighted. Their view is that the Earth must be maintained for future generations, not simply harvested to provide for the needs of its current population. In fact, they argue that biodiversity plays an important part in ecosystem stability.

The Value of Biodiversity

Ecosystems provide human communities with a number of services free of charge, including air and water purification, flood and drought control, pollination of crops and other vegetation, dispersal of seeds, and nutrient cycling. These services have an economic value. If it were possible for humans to pay for ecosystem services based on their market value, biologists estimate that the cost would be approximately $33 trillion annually.

In general, the more species that live in an ecosystem, the more efficient and stable that ecosystem will be. For example, a rain forest can produce much more oxygen than an orchard full of apple trees. Also, many plants, including 75 percent of the world’s staple crop plants, need animal pollinators such as birds and insects to help them reproduce.

In addition, 40 percent of all medicines are derived from plants, animals, and microbes. For example, biologists are developing a painkiller based on an extract from the skin of an Ecuadorian frog. The painkiller is 200 times stronger than morphine, but is not addictive. Every time a plant, animal, or microbe becomes extinct, biologists lose whatever knowledge they might have been able to gain by studying it.

Unanswered Questions

As you have learned, biodiversity is very valuable. Yet questions remain about how best to protect biodiversity. Two of these unanswered questions include

• How can we slow down the current extinction rate?
• Some of the areas with the highest amount of biodiversity are located in developing countries. How can biodiversity be preserved without harming the country’s economic growth?

UPDATES: Straight from the Headlines

• Costa Rican Rainforest Harbors Unknown Salamander Species
• First Lungless Frog Species Discovered in Borneo
• Several New Species Found in Brazil
• Mussels Wreaking Havoc in the Colorado River
• Black-Footed Ferret Recovery Faces Major Set-Backs
• Bats Dying Off in Huge Numbers
• Huge Population of Gorillas Discovered in the Congo Republic
• North American Freshwater Fish Imperiled
• Great Migrations: A Thing of the Past?
• Black Rhinos Released Into the Wild
• Bird Species Takes "Non-Stop Flight" to a Whole New Level
• Invasive Species Spreads Through Europe's Iberian Peninsula
• Scientist Discovers New Spider Species
• Bird Communities Affected by Noise Pollution

What Do You Think?

Last updated July 23, 2009 | Comments (9) | Permalink | UNIT 8: Animals