Extinction

Question 1

What is extinction?

Answer 1

The dying out of groups of organisms

If, over an extended period of time, the birthrate of the species is less than the death rate, then extinction will eventually occur

A species goes extinct if it is not able to adapt to changes in its environment, or compete effectively with other organisms

Question 2

What are mass extinctions?

Answer 2

Periodic rises in the extinction right above the background level

Events caused by catastrophes not changes in habitat or competition

Fossil evidence indicates that there have been several of these events e.g. Permian and cretaceous-tertiary

Question 3

What happens following a mass extinction?

Answer 3

Biodiversity is regained by speciation of the survivors/adaptive radiation

Question 4

What is extinction rate?

Answer 4

Number or % of species becoming extinct

➗

Given area

➗

Unit time

Only an estimate as estimating extinction rate is difficult and approximate

Question 5

Describe human influence on the extinction rate

Answer 5

Current extension rate is one of the highest in history

1000 times higher than the natural background rate

Habitat destruction and overhunting