Difference Between Background Extinction and Mass Extinction

Extinction is the process by which species of plants and animals disappear forever from the Earth. It is a natural process that has been ongoing since life first appeared on the planet, but it can also be accelerated by human activities such as deforestation, hunting, and the introduction of invasive species. Extinction can happen on different scales, and two types of extinction events are background extinction and mass extinction.

What is Background Extinction?

Background extinction is the gradual process through which a small fraction of species die extinct at any one moment during the history of life on Earth. While scholars disagree on the cause of background extinction, others point to deteriorating reproductive fitness and an inability to adjust to environmental changes as possible causes.

Reproductive Fitness and Background Extinction

In evolutionary biology, reproductive fitness is what the expression "survival of the fittest" alludes to. The term "reproductive fitness" is used to describe an organism's capacity to have offspring that are healthy and viable enough to reproduce. The traits of an organism that increase its chances of survival will be selected more often than those that do not. Those characteristics of a population that are detrimental to the survival of a given organism will be eliminated over time. In this way, natural selection achieves its results.

Factors Involved in Background Extinction

Climate change and the introduction of invasive species into new habitats appear to be the primary drivers of background extinction. As long as environmental conditions remain within a species' range of tolerance, the species will continue to thrive. Species will have a tougher difficulty surviving and reproducing if environmental changes push them outside of their ranges before they have had a chance to adjust.

Rising temperatures in tropical regions are threatening the lizard population in the contemporary period. Lizards need time in the sun to warm their bodies so that they can hunt efficiently, but they also need time in the shade to cool down. This is to ensure that their core body temperature doesn't threaten their physiological processes.

Female lizards in certain tropical places are being forced to seek shade before they have hunted long enough to gather the nutrients necessary for reproduction as a result of rising temperatures caused by human activity. A result of this, tropical lizard populations are falling.

The introduction of new predators is a major cause of background extinction. An invasive predator's impact on the ecosystem is often too quick for its victims to adjust to. Large-scale extinctions may result from this. The possible annihilation of several Australian megafauna upon the advent of the first humans is one such instance.

Background extinction is not a dramatic geological or biological event, but rather occurs over time when a species loses reproductive fitness owing to environmental changes occurring too quickly for the species to adapt to.

What is Mass Extinction?

Mass extinctions occur when 75 percent or more of all species on Earth suddenly become extinct, typically within a very short period of geological time (hundreds of thousands to millions of years). Mass extinctions happen all of a sudden on a geological timescale and are caused by a confluence of events that amount to "a very awful day" for the species that existed at the time.

Throughout the past 500 million years, geologists and palaeontologists have identified at least five significant global extinctions. These extinction events are used to demarcate significant epochs in the history of the Earth's geological formation. For instance, the Mesozoic Era spans from the mass extinction that occurred between the Permian and Triassic periods 251 million years ago to the mass extinction that occurred between the Cretaceous and Tertiary periods 66 million years ago, which wiped out the dinosaurs and ammonites, among other things.

An estimated 96% of all living forms disappeared during the Permian mass extinction, making it the deadliest mass-extinction in the history of existence. Several causes, including the release of greenhouse gases from an erupting supervolcano, have been proposed to account for the mass extinction. The simultaneous proliferation of some microorganisms may have resulted in the release of large quantities of hydrogen sulphide, which is lethal to most life on Earth.

So far, only the mass extinction that resulted in the death of the dinosaurs has been connected to a cause that cannot be explained by natural causes. An asteroid hit Earth in the present-day Yucatan Peninsula, on the southeastern coast of the Gulf of Mexico, just before the mass extinction. The Deccan Traps in contemporary India were created by a mix of impact and flood basalts, both of which likely contributed to the Cretaceous-Tertiary mass extinction.

Similarities: Background Extinction and Mass Extinction

There are two distinct forms of extinction, although both result in the loss of a species. Both types of extinction resulting from a lack of time for a population or species to adjust to new circumstances.

Differences: Background Extinction and Mass Extinction

The following table highlights the major differences between Background Extinction and Mass Extinction −


Background Extinction

Mass Extinction


Background extinctions tend to be slow and gradual.

According to geological standards, mass extinctions are sudden and devastating events.


A limited number of species will go extinct at any given moment in geologic history,making background extinctions prevalent.

The average time between mass extinctions is roughly 100 million years.


Background extinctions result from factors that have an impact on an organisms ability to reproduce.

Typically, the extinction of a species is not the direct result of the cataclysmic events that characterise mass extinctions.


Background extinction events are responsible for wiping out the vast majority of extinct species.

The number of species that have died out as a result of major extinctions is quite small.


Background extinction and mass extinction are two different types of extinction events that have distinct causes, consequences, and impacts on the biosphere.

Background extinction is a gradual process that occurs over millions of years and is a normal part of the life cycle of species. Mass extinction is a sudden and dramatic event that results in the rapid disappearance of a large number of species and has significant consequences for the evolution of life on Earth.

Understanding the differences between these two types of extinction events is important for conserving biodiversity and protecting the planet's rich and diverse ecosystems.

Updated on: 14-Apr-2023


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