Keystone Species

A species that supports an entire ecosystem.

• Keystone Species

• Herbivores

• Umbrella Species

• Predators

What statement is TRUE about the graph?

• The prey is the green line because there needs to be more prey than predators.
• The prey is the red line because there needs to be more predators than prey.
• The green line is the producers
• The red line is the producers

in 1995 Wolves were reintroduced to Yellowstone National Park. Which answer below most accurately describes a possible trophic cascade the could result from the reintroduction of wolves?

• wolves reintroduced-> deer population increased -> tree and vegetation cover decreased

• wolves reintroduced-> beaver population decreased -> tree and vegetation cover increased

• wolves reintroduced-> deer population decreased -> tree and vegetation cover increased -> beaver population increased

• wolves reintroduced-> deer population decreased -> beaver population decreased -> songbird population increased

Within a forest ecosystem, there exists three organisms. Wolves, which consume moose. The moose consume balsam fir. A disease moves through the ecosystem, severely decreasing the population of moose. Which of the graphs below show the appropriate impact on the population of wolves and balsam firs?

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• 
• 

In the mid 1900's, the wolves of Yellowstone were deeply affected by humans and their population significantly decreased-- making them endangered, and eventually removing them completely from the Yellowstone ecosystem. The removal of wolves, the top predator, caused what to happen to the biodiversity within Yellowstone?

• A trophic cascade affected the entire food web in Yellowstone, causing some organisms to experience decreases, and others to grow rapidly.

• Biodiversity increased when the wolves disappeared and more species were able to flourish without the wolves.

• A trophic cascade irreversibly ruined the ecosystem in Yellowstone--destroying biodiversity forever.

• The biodiversity of the park was not affected when the wolves were removed.

How did the kelp forest ecosystem change after sea otters were removed?

• sea urchin population increased

• the kelp population decreased

• sea stars increased because there were more sea urchins to eat

• the phytoplankton population decreased