Fiveable
Fiveable

or

Log in

Find what you need to study


Light

Find what you need to study

7.11 Extinction

4 min readjanuary 13, 2023

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Extinctions have occurred throughout Earth's history, and have been caused by a variety of factors including natural disasters, changes in climate, and human activities. These extinctions have had a significant impact on the diversity of life on Earth, as they have led to the loss of many species, and have created opportunities for new forms of life to evolve.

The History of Extinctions

One of the most significant extinction events in Earth's history is the , also known as the "," which occurred about 252 million years ago. This event is believed to have been caused by a combination of factors, including massive volcanic eruptions, changes in ocean chemistry, and a dramatic shift in climate. It is estimated that over 90% of all species on Earth were wiped out as a result of this event. ⚰️

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-PEfO2hkUyVQ6.jpg?alt=media&token=fb520485-4a14-42dd-a270-30e805969ec0

Source: NPR

Another significant extinction event is the , which occurred about 66 million years ago. This event is widely believed to have been caused by the impact of a massive asteroid, which led to a global firestorm, tsunamis, and a "nuclear winter" effect, resulting in the extinction of and many other species.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-PFgEwm6iFmrM.jpg?alt=media&token=47e95a8e-1563-4de6-baaa-ccfb7595b071

Source: ThoughtCo

In addition to these mass extinction events, there have been many other extinctions that have occurred throughout Earth's history. Some of these have been caused by natural factors such as changes in climate, volcanic eruptions, and sea level changes. Others have been caused by human activities, such as habitat destruction, pollution, and over-exploitation of resources.

In addition, extinction is an ongoing process and it continues today! Many species are currently facing the threat of extinction due to human activities, such as deforestation, pollution, and climate change. The loss of biodiversity can have serious consequences for the planet and for human society, as the ecosystem services provided by biodiversity are crucial for human survival. 😔

Ecological Stress

Extinction rates can be rapid during times of , as environmental changes can cause many species to be unable to adapt and survive. can be caused by a variety of factors such as changes in climate, human activities, pollution, and over-exploitation of resources. These changes can cause habitats to be destroyed, and resources to become scarce, making it difficult for many species to survive. When is severe, the can be much higher than during times of stability, leading to the loss of many species in a short period of time. 🦖

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-YxFXPqQKYRmQ.webp?alt=media&token=acf6f028-0084-48a6-9b5e-7c3a7a04b555

Image courtesy of Giphy.

Rate of Speciation vs. Extinction

The amount of diversity in an ecosystem can be determined by the and the . A high , where new species are evolving, will increase the amount of diversity in an ecosystem. However, if the is also high, the net effect on diversity may be neutral or even negative, as the number of species lost may outweigh the number of new species that have evolved. Therefore, it is important to consider both speciation and extinction rates when assessing the diversity of an ecosystem! ♻️

The concept of extinction seems to be scary, but it doesn’t have to be! Sure, in cases of extinction caused by human activity (such as the example above), extinction is most definitely not ideal. Besides, there’s a lot of legislation preventing extinction of species whose numbers have been dwindling for years.

New Niches?

Extinction is part of nature and exists as its own cycle. When a species goes extinct, even if just in one area or ecosystem, it opens a niche for another species to be able to take over. Think about how different our ecosystems would have looked if the were still on top of the food chain! 🍲

What's a niche, you say?

A niche is a specific role or function that a species performs within an ecosystem. When a species goes extinct, its niche becomes available, and other species may be able to evolve and adapt to fill that niche. This process is known as , where a lineage diversifies into many new forms as it adapts to different habitats and ecological niches. This can happen when new habitats become available or when a mass extinction event opens up new ecological niches. During these times, the can be much higher than during times of stasis, as new forms evolve to fill the available niches.

Key Terms to Review (8)

Great Dying

: Also known as the "Permian–Triassic (P–Tr) extinction event", it refers to an extreme biodiversity crisis about 252 million years ago when up to 96% of all marine species and more than two-thirds of terrestrial species died out.

Cretaceous-Paleogene extinction event

: This is another mass extinction event that occurred approximately 66 million years ago, marking the end of the Cretaceous Period and the beginning of the Paleogene Period. It's most famous for leading to the extinction of non-avian dinosaurs.

Permian-Triassic extinction event

: The Permian-Triassic extinction event, also known as the "Great Dying," was a mass extinction that occurred approximately 252 million years ago, marking the end of the Permian Period and the beginning of the Triassic Period. It is considered to be the most severe extinction event in Earth's history, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct.

Dinosaurs

: Dinosaurs are a group of reptiles that appeared during the Mesozoic Era, between 230 and 65 million years ago. They are characterized by their upright stance, with legs located directly beneath the body.

Ecological Stress

: Ecological stress refers to pressure on an organism's ability to survive due to changes in its environment such as temperature shifts, food scarcity or increased competition for resources.

Rate of Speciation

: The rate of speciation is the speed at which new species evolve from a single ancestral species.

Adaptive Radiation

: Adaptive radiation is an evolutionary process where organisms diversify rapidly into a multitude of new forms, particularly when a change in environment makes new resources available, creates new challenges, or opens up new environmental niches.

Rate of Extinction

: The rate of extinction is the number of species that become extinct over a given period of time.

7.11 Extinction

4 min readjanuary 13, 2023

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Samantha Himegarner

Samantha Himegarner

Jed Quiaoit

Jed Quiaoit

Extinctions have occurred throughout Earth's history, and have been caused by a variety of factors including natural disasters, changes in climate, and human activities. These extinctions have had a significant impact on the diversity of life on Earth, as they have led to the loss of many species, and have created opportunities for new forms of life to evolve.

The History of Extinctions

One of the most significant extinction events in Earth's history is the , also known as the "," which occurred about 252 million years ago. This event is believed to have been caused by a combination of factors, including massive volcanic eruptions, changes in ocean chemistry, and a dramatic shift in climate. It is estimated that over 90% of all species on Earth were wiped out as a result of this event. ⚰️

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-PEfO2hkUyVQ6.jpg?alt=media&token=fb520485-4a14-42dd-a270-30e805969ec0

Source: NPR

Another significant extinction event is the , which occurred about 66 million years ago. This event is widely believed to have been caused by the impact of a massive asteroid, which led to a global firestorm, tsunamis, and a "nuclear winter" effect, resulting in the extinction of and many other species.

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-PFgEwm6iFmrM.jpg?alt=media&token=47e95a8e-1563-4de6-baaa-ccfb7595b071

Source: ThoughtCo

In addition to these mass extinction events, there have been many other extinctions that have occurred throughout Earth's history. Some of these have been caused by natural factors such as changes in climate, volcanic eruptions, and sea level changes. Others have been caused by human activities, such as habitat destruction, pollution, and over-exploitation of resources.

In addition, extinction is an ongoing process and it continues today! Many species are currently facing the threat of extinction due to human activities, such as deforestation, pollution, and climate change. The loss of biodiversity can have serious consequences for the planet and for human society, as the ecosystem services provided by biodiversity are crucial for human survival. 😔

Ecological Stress

Extinction rates can be rapid during times of , as environmental changes can cause many species to be unable to adapt and survive. can be caused by a variety of factors such as changes in climate, human activities, pollution, and over-exploitation of resources. These changes can cause habitats to be destroyed, and resources to become scarce, making it difficult for many species to survive. When is severe, the can be much higher than during times of stability, leading to the loss of many species in a short period of time. 🦖

https://firebasestorage.googleapis.com/v0/b/fiveable-92889.appspot.com/o/images%2F-YxFXPqQKYRmQ.webp?alt=media&token=acf6f028-0084-48a6-9b5e-7c3a7a04b555

Image courtesy of Giphy.

Rate of Speciation vs. Extinction

The amount of diversity in an ecosystem can be determined by the and the . A high , where new species are evolving, will increase the amount of diversity in an ecosystem. However, if the is also high, the net effect on diversity may be neutral or even negative, as the number of species lost may outweigh the number of new species that have evolved. Therefore, it is important to consider both speciation and extinction rates when assessing the diversity of an ecosystem! ♻️

The concept of extinction seems to be scary, but it doesn’t have to be! Sure, in cases of extinction caused by human activity (such as the example above), extinction is most definitely not ideal. Besides, there’s a lot of legislation preventing extinction of species whose numbers have been dwindling for years.

New Niches?

Extinction is part of nature and exists as its own cycle. When a species goes extinct, even if just in one area or ecosystem, it opens a niche for another species to be able to take over. Think about how different our ecosystems would have looked if the were still on top of the food chain! 🍲

What's a niche, you say?

A niche is a specific role or function that a species performs within an ecosystem. When a species goes extinct, its niche becomes available, and other species may be able to evolve and adapt to fill that niche. This process is known as , where a lineage diversifies into many new forms as it adapts to different habitats and ecological niches. This can happen when new habitats become available or when a mass extinction event opens up new ecological niches. During these times, the can be much higher than during times of stasis, as new forms evolve to fill the available niches.

Key Terms to Review (8)

Great Dying

: Also known as the "Permian–Triassic (P–Tr) extinction event", it refers to an extreme biodiversity crisis about 252 million years ago when up to 96% of all marine species and more than two-thirds of terrestrial species died out.

Cretaceous-Paleogene extinction event

: This is another mass extinction event that occurred approximately 66 million years ago, marking the end of the Cretaceous Period and the beginning of the Paleogene Period. It's most famous for leading to the extinction of non-avian dinosaurs.

Permian-Triassic extinction event

: The Permian-Triassic extinction event, also known as the "Great Dying," was a mass extinction that occurred approximately 252 million years ago, marking the end of the Permian Period and the beginning of the Triassic Period. It is considered to be the most severe extinction event in Earth's history, with up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct.

Dinosaurs

: Dinosaurs are a group of reptiles that appeared during the Mesozoic Era, between 230 and 65 million years ago. They are characterized by their upright stance, with legs located directly beneath the body.

Ecological Stress

: Ecological stress refers to pressure on an organism's ability to survive due to changes in its environment such as temperature shifts, food scarcity or increased competition for resources.

Rate of Speciation

: The rate of speciation is the speed at which new species evolve from a single ancestral species.

Adaptive Radiation

: Adaptive radiation is an evolutionary process where organisms diversify rapidly into a multitude of new forms, particularly when a change in environment makes new resources available, creates new challenges, or opens up new environmental niches.

Rate of Extinction

: The rate of extinction is the number of species that become extinct over a given period of time.