Background extinction

Definition

Background extinction is the standard rate of extinction in Earth's geological and biological history before humans became a primary contributor to extinctions. It refers to the normal rate of loss of species due to natural evolutionary and ecological processes.

5 Must Know Facts For Your Next Test

1. Background extinction rates are estimated from fossil records and historical data.
2. The average background extinction rate is thought to be about one species per million species per year.
3. Factors contributing to background extinction include changes in climate, habitat loss, and competition.
4. Background extinction is contrasted with mass extinctions, which involve a significant percentage of all life forms dying out in a relatively short period.
5. Current extinction rates are believed to be much higher than the background rate due to human activities.

Review Questions

• What is the difference between background extinction and mass extinction?
• List three factors that contribute to background extinction.
• Why are current extinction rates higher than historical background rates?

Related terms

Mass Extinction: A widespread and rapid decrease in the biodiversity on Earth, typically characterized by the loss of a large number of species in a relatively short period.

Anthropogenic Extinction: Extinction caused directly or indirectly by human activities such as habitat destruction, pollution, overhunting, or introducing invasive species.

Biodiversity Hotspot: A biogeographic region with significant levels of biodiversity that is under threat from humans.