Gray wolves, once the top predators in Yellowstone National Park, were hunted to extinction there in 1926. In 1995, 15 wolves were brought to Yellowstone from Alberta. The wolf population has now grown to 300. The forest community in Yellowstone National Park can be described by a top-down model of community organization. Wolves hunt and eat elk. Elk are herbivores that prefer riparian vegetation (plants growing next to streams and lakes). Ravens, bears, and eagles feed on elk carcasses. How would you expect the return of the wolves to Yellowstone to affect the other species there

OPTIONS:

a. Bear populations would decline.  b. Riparian vegetation would decline.  c. Elk populations would decline.

c. Elk populations would decline.

Explanation:

The gray wolf can be regarded as a keystone predatory species. The absence or decrease of the population of a keystone predator in an ecosystem largely has a negative impact on the balance of the ecosystem, as well as the population of other organisms in that ecosystem.  

In the Yellowstone ecosystem, Elk population is controlled by the gray wolf, as they are hunted down by the gray wolf. As stated in the question, these elks that are being hunted by gray wolf, their carcasses serve as sources of food for the ravens, bears, and the eagles. This means, the presence of wolf in the ecosystem would make enough food available for these animals as their population increases.

What to be expected as the gray wolf is returned is that, the population of elk would decline, since gray wolf would hunt them down. Also, since elk population feed heavily on riparian vegetation, these vegetation would increase rather than decline.

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