Bell Questions 1/12/11

1. What is a mass extinction?

2. What is the difference between an endangered species and a threatened species?

3. What is one way a species may be prone to extinction?

How Do Humans Cause Extinctions?

1. Habitat Destruction and Fragmentation

• Habitat has been destroyed or broken up by roads, canals, fences and homes.

• Florida panther requires large area of forest and large amount of prey.

• In 2001 less than 80 panthers east of Mississippi

2. Invasive Exotic Species

• exotic species - species that is not native to a particular region.

• Exotic species can threaten native species that have no natural defenses against them.

Cheatgrass

3. Harvesting, Hunting, and Poaching

• Poaching - the illegal harvesting of fish, game, or other species.

• Excessive hunting can lead to extinction. (passenger pigeons)

4. Pollution

• Pesticides, cleaning agents, drugs, and other chemicals used by humans are making their way into food webs around the globe.

• Bald Eagles and DDT

Areas of Critical Biodiversity

• endemic species - species that is native to a particular place and that is found only there

Biodiversity Hotspots

Tropical Rain Forests

• Half of world’s species live in these forests that cover only 7% of earth’s land surface.

Coral Reefs and Coastal Ecosystem

• Reefs provide millions of people with food, tourism revenue, coastal protection, and sources of new chemicals.

Islands

• Colonized by a limited number of species that can evolve into new species.

• Thus, islands often hold a very distinct but limited set of species.

Galapagos Islands

Biodiversity in the United States

• Unique ecosystems in the U.S.; Florida Everglades, the California coastal region, Hawaii, the Midwestern prairies, and the forests of the Pacific Northwest.