Green world hypothesis

The green world hypothesis, or HSS, proposes that predators are the primary regulators of ecosystems: they are the reason the world is 'green', by regulating the herbivores that would otherwise consume all the greenery.

History

The green world hypothesis was likely first proposed in a 1957 course by Frederick Edward Smith at the University of Michigan.[1][2]

In 1960, Nelson Hairston, Smith, and Lawrence Slobodkin published a paper laying out the green world hypothesis. The name HSS derives from the first letters of each of their surnames.[3][4]

Robert T. Paine did experiments in 1966[5] with Pisaster ochraceus which illustrated their role as a keystone species in regulating Mytilus californianus.[6]

James Estes and John Palmisano did similar experiments with otters, sea urchins, and kelp, where otter presence increased kelp presence in a trophic cascade.[5]

John Terborgh examined Venezuelan valleys with and without predators in 2006, demonstrating the green world hypothesis on land.[7][8]

Criticism

The plant self-defense hypothesis proposes that plants are not entirely consumed by herbivores primarily because of their adaptations against it (thorns, toxicity, cellulose, etc.).[2]

References

  1. Paine, Robert T. (1 January 2013). "Frederick Edward Smith: 1920–2012". Bulletin of the Ecological Society of America. 94 (1): 20–23. doi:10.1890/0012-9623-94.1.20. ISSN 0012-9623.
  2. Eisenberg, Cristina. "Living in a Landscape of Fear: How Predators Impact an Ecosystem". Scientific American. Retrieved 2023-09-13.
  3. "CHAPTER 3. Trophic Dynamics: Why Is the World Green?", CHAPTER 3. Trophic Dynamics: Why Is the World Green?, Princeton University Press, pp. 23–54, 2010-07-01, doi:10.1515/9781400834174.23/html, ISBN 978-1-4008-3417-4, retrieved 2023-09-13
  4. Hairston, Nelson G.; Smith, Frederick E.; Slobodkin, Lawrence B. (November 1960). "Community Structure, Population Control, and Competition". The American Naturalist. 94 (879): 421–425. doi:10.1086/282146. ISSN 0003-0147.
  5. "The Crucial Role of Predators: A New Perspective on Ecology". Yale E360. Retrieved 2023-09-13.
  6. Some Animals Are More Equal than Others: Keystone Species and Trophic Cascades, retrieved 2023-09-13
  7. admin-innovation (2006-02-28). "Ecologists explain why the world is green". Innovations Report. Retrieved 2023-09-13.
  8. "Predators Keep the World Green, Ecologists Find". Duke Today. 2006-02-28. Retrieved 2023-09-13.
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