Keystone Species Concept Quiz

Questions and Answers

Which species is cited as a classic example of a keystone species that acts as an ecosystem engineer?

Red-tailed hawk

North American beaver (correct)

Eastern grey squirrel

North American wolf

What role do mycorrhizal fungi play in forest ecosystems?

They primarily compete with trees for sunlight.

They inhibit the growth of tree species.

They enhance the tree’s ability to absorb soil nutrients. (correct)

They extract nutrients from trees for their own survival.

What can be the result of introducing an exotic species to a community?

Creating new food sources for native species.

Promoting the growth of keystone species.

Causing damage similar to the loss of a keystone species. (correct)

Strengthening the ecosystem through biodiversity.

Why are keystone species crucial for ecosystem health?

They maintain community structure and influence that benefit other species. Signup and view all the answers

How can the loss of a keystone species affect a forest community?

It can destabilize the community and lead to loss of biodiversity. Signup and view all the answers

What defines a keystone species in a community?

A species that plays a disproportionately important role relative to its abundance Signup and view all the answers

Which of the following is an example of a keystone species as described in the content?

The sea star Pisaster, which preys on mussels Signup and view all the answers

What outcome occurred when Pisaster was removed from the intertidal community?

Eight other species were driven to extinction Signup and view all the answers

In the context of keystone species, what role can figs and nectar play in tropical forests?

They provide essential nutrients during times of low food availability Signup and view all the answers

What characteristic distinguishes keystone pollinators from more abundant ones?

They are often the rare species that perform essential pollination roles Signup and view all the answers

What is a consequence of the hunting of Old World fruit bats in the South Pacific?

The potential loss of entire island plant communities Signup and view all the answers

Which factor would disqualify a species from being a keystone species?

Fulfilling a vital function that can be easily replaced Signup and view all the answers

Which of the following statements about keystone species is incorrect?

They must be the most populous species in the community Signup and view all the answers

Study Notes

Keystone Species Overview

A keystone species has a disproportionately large impact on its ecosystem relative to its abundance.
These species can influence community structure and biodiversity despite being less numerous.

Importance of Keystone Species

Removal of a rare keystone species can result in unexpected ecological shifts and loss of biodiversity.
Unlike abundant species, keystone species maintain balance among various populations.

Example: Pisaster and Mytilus

The sea star Pisaster serves as a key predator in a Pacific intertidal community.
Removal of Pisaster leads to unchecked population growth of mussels (Mytilus), causing competition with other species and subsequent loss of eight species.

Keystone Food Sources in Tropical Forests

Figs, nectar, and specific fruits constitute less than 1% of plant diversity in Central and South American tropical forests but act as critical food sources.
During periods of low food availability, these keystone species support non-migratory herbivores.

Types of Keystone Species

Keystone species can also function through mutualistic interactions:
- Irreplaceable Pollinators: Certain rare pollinators, like Old World fruit bats, are essential for plant reproduction and biodiversity on South Pacific islands.
- Habitat Modifiers: North American beavers, despite low biomass, reshape ecosystems by creating ponds that support diverse species.
- Mutualistic Species: Mycorrhizal fungi aid trees in nutrient absorption, critical for forest community health and resource availability.

Impact of Exotic Species

Introduction of exotic species can mimic the effects of losing a keystone species, disrupting ecological balances.
The extinction of a keystone species or presence of invasive species underscores a community's dependence on specific organisms for stability.

Description

Test your understanding of keystone species and their ecological significance. This quiz will cover the role of these species in food webs and community health. Explore the importance of species that may not be the most abundant yet impact their ecosystems significantly.