Sustaining Biodiversity: The Species Approach Chapter 9

Sustaining Biodiversity:

The Species Approach

Chapter 9

Core Case Study: The Passenger Pigeon:

Gone Forever

? Passenger pigeon hunted to extinction by 1900

? Commercial hunters used a "stool pigeon¡±

? Archeological record shows five mass

extinctions

? Human activities: hastening more extinctions?

Passenger Pigeon

9-1 What Role Do Humans Play in the

Premature Extinction of Species?

? Concept 9-1A We are degrading and

destroying biodiversity in many parts of the

world, and these threats are increasing.

? Concept 9-1B Species are becoming extinct

100 to 1,000 times faster than they were before

modern humans arrived on the earth (the

background rate), and by the end of this century,

the extinction rate is expected to be 10,000

times the background rate.

Human Activities Are Destroying and

Degrading Biodiversity

? Human activity has disturbed at least half of the

earth¡¯s land surface

? Fills in wetlands

? Converts grasslands and forests to crop fields

and urban areas

? Degraded aquatic biodiversity

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