In the Gizmos: Ecosystems STEM Case Study (Food Web Mystery), if the wolf population is nearly gone at the start of the simulation, what is the immediate effect on the elk population (Population Increases or Population Decreases), and why?

What the food web is telling you

A food web shows who eats whom, so you can predict population changes when one species changes. Here, the key link is that wolves are predators and elk are prey.

Immediate effect when wolves disappear

If the wolf population is nearly gone, the elk lose a major predator. That means the elk death rate from predation decreases right away.

So what happens to elk?

With fewer elk being eaten, more elk survive long enough to reproduce. Therefore, the elk population increases in the short term.

Quick check using cause and effect

• Wolves down $\rightarrow$ less predation on elk
• Less predation $\rightarrow$ higher elk survival
• Higher survival $\rightarrow$ elk population increases