D4.2.5 Role of keystone species in the stability of ecosystems Notes

Keystone Species Are Critical for Ecosystem Stability

1. Keystone species play a disproportionate role in maintaining the structure and stability of ecosystems.
2. Removing a keystone species often triggers cascading effects that destabilize the ecosystem.

What Defines a Keystone Species?

1. A keystone species has an impact on its ecosystem that is far greater than its abundance would suggest.
2. Key Characteristics:
   1. Disproportionate Influence: Their impact outweighs their biomass or population size.
   2. Regulation of Ecosystem Dynamics: They control dominant species, promote biodiversity, and enhance ecosystem functions.
   3. Triggers Trophic Cascades: Their removal can alter food webs and ecological interactions.

Example

The ochre sea star (Pisaster ochraceus) prevents mussels from dominating rocky shores, maintaining biodiversity.

Importance of Keystone Species

Keystone Species Control Dominant Species

Keystone species regulate populations that might otherwise dominate and outcompete others.

Biodiversity Flourishes Under Keystone Species

By limiting competition, keystone species create conditions for a diverse range of species to coexist.

Ecosystem Functions Depend on Keystone Species

Keystone species contribute to nutrient cycling, habitat creation, and energy flow, supporting ecosystem resilience.

What Happens When Keystone Species Are Removed?

1. Removing keystone species disrupts ecosystems in three key ways:
   1. Biodiversity Declines: Dominant species monopolize resources, crowding out others.
   2. Food Webs Collapse: Predator-prey dynamics are destabilized.
   3. Ecosystem Functions Fail: Processes like nutrient cycling are interrupted.

Conserving Keystone Species Benefits Entire Ecosystems

1. Protecting keystone species ensures the health and stability of ecosystems. Key strategies include:
   1. Habitat Preservation: Ensuring keystone species have the environments they need to thrive.
   2. Restoration Projects: Reintroducing species like wolves to areas where they’ve been lost.
   3. Ongoing Research: Identifying and monitoring keystone species to understand their ecological roles.