Question

Biologists examined the effects of reintroducing wolves into Yellowstone National Park of the United States. They found that by preying on elk, wolves altered the foraging behavior of the elk; the elk spent less time browsing near streambanks. This allowed the regrowth of important vegetation, which had large positive impacts on the ecosystem at large. When a relatively small number of individuals, like wolves, have disproportionate impacts on the ecosystem, they are referred to as a... A. Foundation species B. Portal species C. Keystone species D. Cornerstone species E. Pivotal species

Short answer

Keystone species

Step-by-step solution

Understand the Concept

Read the question carefully and understand that it’s asking about a term used to describe species that have a disproportionately large impact on their ecosystem.

Recall Key Terms

Recall definitions of foundational ecological terms. A keystone species is a species whose presence and role within an ecosystem have a disproportionate effect on other organisms within the system.

Match Definitions to Terms

Identify that a small number of individuals having a large impact on the ecosystem fits the definition of a keystone species.

Choose the Best Answer

Among the given options: Foundation species, Portal species, Keystone species, Cornerstone species, and Pivotal species, the term that best fits the description is Keystone species.

Key concepts

Ecosystem Impact

An ecosystem is a community of living organisms interacting with one another and their physical environment. Ecosystems can be highly sensitive to changes, particularly when it involves keystone species. In Yellowstone National Park, reintroducing wolves had a substantial impact. Wolves prey on elk, which altered the elks' foraging behavior. As a result, there was less browsing on streambank vegetation. This scenario allowed plants to regenerate, which had multiple positive effects. Increased vegetation strengthened streambanks, which improved water quality and provided better habitats for various species. This ripple effect showcases how a single species can influence the entire ecosystem.
Understanding ecosystem impact helps us appreciate the interconnectedness of nature and the significance of preserving keystone species.

Species Interaction

Species interaction refers to how different species within an ecosystem interact with one another. These interactions include predation, competition, mutualism, and more. In Yellowstone, the reintroduction of wolves showcased predatory interactions. Wolves hunting elk modified how elk behaved, specifically where and what they foraged. This is a prime example of direct interaction.
However, this direct interaction led to indirect effects on other species. For instance, the regrowth of vegetation along streambanks provided habitats and food for other creatures, such as birds and beavers. This cascade effect from one species' behavior impacts many other organisms, demonstrating the complex web of interactions in an ecosystem.
Understanding species interactions helps ecologists predict changes and manage wildlife more effectively.

Yellowstone Wolves

Yellowstone National Park is a famous example of rewilding efforts with the reintroduction of wolves in 1995. Before their return, the elk population was high, leading to overgrazing and damaged vegetation. Wolves balanced the ecosystem by reducing and changing elk behaviors. This allowed vegetation to recover.
The reintroduction of the wolves is also linked to increased biodiversity. With healthier streambank vegetation, species like beavers, which rely on willow and other plants, began to thrive. In turn, beaver ponds created aquatic habitats that benefited fish and amphibians.
The Yellowstone case is remarkable because it shows the positive effects of restoring a keystone species. It educates us on the importance of each species to ecosystem health and how human management can foster natural balance.