Test Your Knowledge on Keystone Species and Trophic Cascades

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Questions and Answers

What is the green world hypothesis?

A hypothesis that plants are the most important species in an ecosystem.

A hypothesis that all species have equal impact on ecosystems.

A hypothesis that abiotic factors have the greatest impact on ecosystems.

A hypothesis that predators keep herbivores in check, which regulates ecosystems. (correct)

Who coined the term 'keystone species'?

A group of ecologists

The text does not mention who coined the term

James Estes

Robert Paine (correct)

What is the difference between keystone species and most species?

The text does not mention any difference between keystone species and most species.

Keystone species are the smallest species, while most species are large.

Keystone species have a huge impact, while most species do not have large impacts. (correct)

Keystone species are the most abundant species, while most species are rare.

What did James Estes discover about sea otters?

Sea otters were controlling the urchins that fed on kelp, and removing them caused the kelp forests to disappear. Signup and view all the answers

What are trophic cascades?

The effects that predators have on the abundance and behavior of their prey and other species within an ecosystem. Signup and view all the answers

What did the discovery of trophic cascades challenge?

The prevailing view of ecology, which focused on bottom-up effects, or the effects of abiotic factors like temperature and rainfall on ecosystems. Signup and view all the answers

What happened when sea otters were removed from the Aleutian Islands ecosystem?

The decline of kelp forests due to an increase in sea urchin populations. Signup and view all the answers

What can ignoring the role of apex predators and top-down effects in ecosystems lead to?

Mistakes and risks to the health and stability of these systems. Signup and view all the answers

What are keystone species?

Species that have a disproportionate effect on the ecosystem relative to their abundance Signup and view all the answers

What is the green world hypothesis?

Predators keep herbivores in check, which regulates ecosystems Signup and view all the answers

What is the main idea behind trophic cascades?

Predators have effects on the abundance and behavior of their prey and other species within an ecosystem Signup and view all the answers

What did Robert Paine's experiment with removing starfish from a rocky Pacific shore show?

One predator could regulate the composition of an entire community Signup and view all the answers

What did James Estes discover about sea otters?

They were controlling the urchins that fed on kelp Signup and view all the answers

What is the danger of ignoring the role of apex predators and top-down effects in ecosystems?

Mistakes and risks to the health and stability of ecosystems Signup and view all the answers

What did the depletion of whales in the North Pacific lead to?

An increase in killer whale populations, which in turn led to the decline of sea otter populations and the subsequent decline of kelp forests Signup and view all the answers

What did Robert Paine's experiment with removing urchins from tide pools show?

They were keeping kelp from growing, violating the green world hypothesis Signup and view all the answers

Study Notes

The Role of Keystone Species in Ecosystems

The Earth is home to many habitats, each with a community of plants and animals, and each species is present in different numbers.
The green world hypothesis proposed that predators keep herbivores in check, which regulates ecosystems.
Robert Paine's experiment with removing starfish from a rocky Pacific shore showed that one predator could regulate the composition of an entire community.
Paine coined the term "keystone species" to describe the power a single species can exert on an ecosystem.
Keystone species have a huge impact, which extends well beyond the species they primarily prey on.
Most species do not have large impacts, and it takes experiments to tease out the difference.
Paine's experiment with removing urchins from tide pools showed that they were keeping kelp from growing, violating the green world hypothesis.
James Estes continued Paine's work by studying the role of sea otters in the organization of nature.
Estes discovered that sea otters, a predator, were controlling the urchins that fed on kelp, and removing them caused the kelp forests to disappear.
Sea otters are another keystone species that regulate the structure of coastal marine communities.
Estes later noticed that otter populations seemed to be declining, and discovered that killer whales were now eating otters due to the depletion of whales.
The depletion of keystone species can have cascading effects on entire ecosystems.The Discovery of Trophic Cascades and Keystone Species
Trophic cascades are the effects that predators have on the abundance and behavior of their prey and other species within an ecosystem.
In the 1960s, ecologist Robert Paine discovered the concept of keystone species, which are species that have a disproportionate effect on the ecosystem relative to their abundance.
Paine's experiment involved removing the starfish, a keystone predator, from a rocky shore ecosystem and observing the subsequent changes in the abundance of other species.
Paine's experiment demonstrated that keystone species can have a profound effect on the ecosystem and that the removal of a keystone species can lead to the decline of other species within that ecosystem.
Paine's work inspired ecologist James Estes, who conducted a similar experiment in the Aleutian Islands, where he found that the removal of sea otters, another keystone predator, led to the decline of kelp forests.
Estes' work led to the discovery of trophic cascades, which are the effects that predators have on the abundance and behavior of their prey and other species within an ecosystem.
The discovery of trophic cascades challenged the prevailing view of ecology, which focused on bottom-up effects, or the effects of abiotic factors like temperature and rainfall on ecosystems.
The discovery of trophic cascades highlighted the importance of top-down effects, or the effects of predators on ecosystems.
In the Aleutian Islands, the removal of sea otters led to an increase in sea urchin populations, which in turn led to the decline of kelp forests.
In the North Pacific, the removal of whales led to an increase in killer whale populations, which in turn led to the decline of sea otter populations and the subsequent decline of kelp forests.
The discovery of trophic cascades and keystone species has changed the way ecologists and conservationists view ecosystems and has given them new tools for managing and protecting these systems.
Ignoring the role of apex predators and top-down effects in ecosystems can lead to mistakes and risks to the health and stability of these systems.

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Description

Test your knowledge on keystone species and trophic cascades with our quiz! Learn about the profound effects that these species can have on entire ecosystems and how the removal of a single species can lead to cascading effects throughout the food web. Challenge yourself to understand the importance of top-down effects on ecosystems and the role of apex predators in regulating these systems. Take our quiz to see how much you know about these fascinating ecological concepts.