Question

which of the following is an example of a keystone species? gray wolf in yellowstone national park white - tailed deer in pennsylvania grass in a prairie ecosystem house cat in a neighborhood what happened when wolves were removed from yellowstone national park? the elk population decreased plant biodiversity decreased because elk overgrazed rivers dried up nothing changed which of the following describes a top - down effect caused by a keystone predator? more sunlight reaches the forest floor prey populations increase when predators are removed soil nutrients cycle faster water evaporates more quickly

Explanation:

1. A keystone species has a disproportionately large impact on its ecosystem relative to its abundance. Gray wolves in Yellowstone are a classic example as they control prey populations like elk, which in turn affects vegetation and other species.
2. When wolves were removed from Yellowstone, elk populations increased without predation pressure. The over - grazing by elk led to a decrease in plant biodiversity.
3. A top - down effect caused by a keystone predator is when the removal of the predator leads to an increase in prey populations, as the predator no longer controls them.

Answer:

1. Gray wolf in Yellowstone National Park
2. Plant biodiversity decreased because elk overgrazed
3. Prey populations increase when predators are removed