Keystone Species

Definition

A keystone species is a species that has a disproportionately large impact on its ecosystem relative to its abundance. These species play critical roles in maintaining the structure, diversity, and health of their environment, often influencing food webs, habitat requirements, and interactions with invasive species.

5 Must Know Facts For Your Next Test

1. Keystone species can include predators, prey, plants, and even microorganisms that have a large effect on their ecosystem's structure and function.
2. The removal of a keystone species can lead to significant changes in the ecosystem, potentially resulting in decreased biodiversity and altered community dynamics.
3. Examples of keystone species include sea otters in kelp forests, wolves in Yellowstone National Park, and fig trees in tropical forests.
4. Keystone species are not always the most abundant species; instead, their ecological role is what makes them critical to the ecosystem's health.
5. Invasive species can disrupt the balance maintained by keystone species, leading to negative impacts on native biodiversity and ecosystem stability.

Review Questions

• How does the role of a keystone species influence food webs within an ecosystem?
  • Keystone species play vital roles in food webs by controlling populations of other species and maintaining balance within the ecosystem. For instance, predators that are considered keystone species help regulate prey populations, which can prevent overgrazing and support plant diversity. This interaction not only sustains food sources for various organisms but also promotes overall ecological stability.
• Evaluate how the presence or absence of a keystone species can affect habitat requirements for other organisms in its ecosystem.
  • The presence of a keystone species can create or enhance habitats necessary for other organisms to thrive. For example, beavers as keystone species construct dams that create wetlands, providing crucial habitats for a variety of wildlife. Conversely, if a keystone species were to disappear, it could lead to habitat loss or degradation for many dependent organisms, ultimately disrupting the entire ecological community.
• Assess the implications of introducing an invasive species into an ecosystem where a keystone species exists.
  • Introducing an invasive species into an ecosystem with a keystone species can have profound implications, potentially leading to competition for resources and altering trophic interactions. The invasive species may outcompete the keystone species or disrupt its role in maintaining ecological balance. This disruption can result in a cascade effect that diminishes biodiversity and destabilizes the entire ecosystem, highlighting the importance of protecting keystone species from invasive threats.

Related terms

Trophic Cascade: A process by which changes in the population of one species can cause significant effects on other species at different trophic levels, often leading to dramatic shifts in ecosystem structure.

Ecosystem Engineers: Species that create, modify, or maintain habitats for other organisms, thereby influencing community structure and biodiversity within their ecosystems.

Biodiversity:

The variety of life in a particular habitat or ecosystem, including the number of different species and the genetic diversity within those species.