A keystone species is one whose impact on its ecosystem is far greater than its abundance would suggest. Sea otters, for example, are not especially numerous along the Pacific coast, but by preying on sea urchins they prevent the urchins from devouring kelp forests. Without sea otters, kelp ecosystems quickly collapse.
Which choice best describes the structure of the text?
- A
It refutes a popular claim about sea otters.
- B
It traces the chronological history of marine biology.
- C
It compares two competing ecological theories.
- Dcheck_circle
It defines a concept and supports it with a specific example.
Explanation
The text defines "keystone species" and exemplifies with sea otters. A captures the definition-and-example structure.