Lect 32 Extinction PP outline

Lect 32 Extinction PP outline - Extinction The loss of the...

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Extinction 0. The loss of the last member of a species. 1. Extinction is irreversible. 2. Extinction leads to a biologically impoverished world. 3. However, extinction is a naturally occurring process. 4. Extinction is the ultimate fate of all species on Earth. 0. Including humans! Mass Extinctions 0. Throughout the history of life on Earth we have seen mass extinctions before. 1. A mass extinction is a period where many more species are going extinct compared to background levels. Mass Extinctions 2. 65 million years ago, at the end of the Cretaceous Period, the rate of extinction was about as high as we had ever seen on Earth before. 3. The end of the age of dinosaurs. 4. At that time the extinction rate was estimated to be 1 species every 500-1,000 years. Mass Extinctions 5. Recently, for the last 10,000 years, we have been in another period of mass extinction. 6. This period of mass extinction corresponds well with the spread of humans throughout the world. 0. World wide dispersal 1. Human radiation 2. Where humans went, a wave of extinctions followed, going back at least 10,000 years. Mass extinctions 7. The current rate of mass extinctions is getting faster and faster. 8. Just looking at two Classes of vertebrates – birds and mammals: 3. 10K – 1600 1 species / 800 years 4. 1600 – 1980 1 species / 3 years 0. We lost 194 bird species and 106 mammal species that we know of, probably even more. 5. 1980 – 2000 1 species / 6 months Mass extinctions 9. In addition, there are a great many endangered species. 6.
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This note was uploaded on 04/26/2008 for the course BIOLOGY 118 taught by Professor Richardson during the Spring '08 term at Winona.

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Lect 32 Extinction PP outline - Extinction The loss of the...

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