What is the Difference Between Mass Extinction and Background Extinction?

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The difference between mass extinction and background extinction lies in the rate and scale of species loss. Here are the key distinctions between the two types of extinction events:

Mass Extinction:

  • Occurs quickly and wipes out large amounts of species at a time.
  • A sudden and dramatic event that results in the rapid disappearance of a large number of species.
  • There have been five mass extinctions on Earth, with the average time between mass extinctions being roughly 100 million years.
  • Examples include the die-off of the dinosaurs (K-T extinction) and the Permian mass extinction, which killed off about 90% of the species living at the time.
  • Causes of mass extinctions may include climate change, volcanic eruptions, sea level change, continental movement, and asteroid impacts.

Background Extinction:

  • A gradual process that occurs over millions of years and is a normal part of earth's history.
  • Affects one or a few species and occurs in one locality rather than globally.
  • Results from factors that impact an organism's ability to reproduce.
  • Responsible for wiping out the vast majority of extinct species.
  • The current rate of human-caused extinction is 1,000 times greater than past background extinctions, mostly due to habitat loss and overharvesting.

In summary, mass extinctions are sudden and catastrophic events that lead to the rapid disappearance of a large number of species, while background extinctions are gradual, localized events that occur as a natural part of earth's history and are responsible for the majority of species loss.

Comparative Table: Mass Extinction vs Background Extinction

Here is a table comparing the differences between mass extinction and background extinction:

Feature Mass Extinction Background Extinction
Definition A sudden and dramatic event that results in the rapid disappearance of a large percentage of species. A gradual process that occurs over millions of years and is a normal part of the life cycle of species.
Rate of Extinction Rapid and large-scale. Relatively constant rate over geological timescales.
Causes Often due to cataclysmic events, such as natural disasters, climate change, or the introduction of invasive species. Factors that impact an organism's ability to reproduce, such as competition for resources, predation, changes in environmental conditions, and the emergence of new species.
Impact on Biosphere Results in the wiping out of many species, often with lasting consequences for ecosystems. A natural part of the evolutionary process, contributing to the ongoing formation of new species and ecological niches.
Duration Occurs over a relatively short period of time, mostly due to human activities. Occurs over millions of years as a normal part of Earth's geological history.
Types of Extinctions Results from large-scale disruptive events, such as catastrophic events, climate change, or invasive species. Caused by a combination of factors, including competition for resources, predation, changes in environmental conditions, and the introduction of new species.
Average Time Between Events Roughly 100 million years. Occurs at a relatively constant rate throughout Earth's history.

It is essential to understand the differences between mass extinction and background extinction to comprehend the impact of these events on Earth's biosphere and the consequences of various human activities on extinction rates.