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9 Questions

What is a keystone species?

Who introduced the concept of keystone species?

What is the role of a keystone species in an ecosystem analogous to?

What is an example of a classic keystone species?

What is the role of sea otters in kelp forests?

What is the role of keystone predators in increasing biodiversity?

What are keystones mutualists?

What is an example of a keystone species that is an ecosystem engineer?

What is the criticism of the concept of keystone species?


Keystone Species: Species that has a disproportionately large effect on its environment relative to its abundance

  • Keystone species play a critical role in maintaining the structure of an ecological community, affecting many other organisms in an ecosystem, and helping to determine the types and numbers of various other species in the community.
  • Without keystone species, the ecosystem would be dramatically different or cease to exist altogether.
  • The role that a keystone species plays in its ecosystem is analogous to the role of a keystone in an arch.
  • The concept of the keystone species was introduced in 1969 by zoologist Robert T. Paine.
  • A classic keystone species is a predator that prevents a particular herbivorous species from eliminating dominant plant species.
  • Sea otters protect kelp forests from damage by sea urchins.
  • Keystone predators may increase the biodiversity of communities by preventing a single species from becoming dominant.
  • Keystones mutualists are organisms that participate in mutually beneficial interaction, the loss of which would have a profound impact upon the ecosystem as a whole.
  • The beaver is a well-known ecosystem engineer and keystone species.
  • The term has been applied widely in different ecosystems and to predators, prey, and plants (primary producers), inevitably with differing ecological meanings.
  • The term has thus been given quite different meanings in different cases.
  • The concept has been criticized by L. S. Mills and colleagues for oversimplifying complex ecological systems.


Test your knowledge of the ecological world with our Keystone Species quiz! Learn about the critical role that keystone species play in maintaining the structure of an ecosystem, and how they affect the types and numbers of other species in the community. From predators to mutualists, this quiz covers a wide range of keystone species and their ecological importance. Take the quiz and discover how much you know about these fascinating organisms that are essential to the health of our planet.

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