How can a change to one species trigger a chain reaction that affects many more?

The video discusses the significant impact that certain species can have on ecosystems, particularly those that play a crucial organizing role, known as keystone species. These species have a disproportionate effect on the diversity and stability of the ecosystem. Changes in their population, whether an increase or removal, can lead to dramatic chain reactions affecting the abundance of other species. The ecosystem may collapse without them or thrive upon their reintroduction.

What is the role of certain species in an ecosystem as discussed in the first section?

• They only affect plant life.

• They can trigger chain reactions.

• They have no significant impact.

• They are always predators.

What defines a keystone species according to the second section?

• A species that is always a predator.

• A species with a significant impact on ecosystem diversity.

• A species with a minor role in the ecosystem.

• A species that is the most abundant.

How does the presence of a keystone species affect an ecosystem?

• It always causes the ecosystem to collapse.

• It can stabilize the ecosystem.

• It can lead to a decrease in diversity.

• It has no effect.

What might happen if a keystone species is removed from an ecosystem?

• The ecosystem will remain unchanged.

• The ecosystem may collapse.

• The ecosystem will always thrive.

• The ecosystem will become more diverse.

What is a possible outcome when a keystone species is reintroduced into an ecosystem?

• The ecosystem will become less diverse.

• The ecosystem will thrive again.

• The ecosystem will remain unchanged.

• The ecosystem will collapse.