The principle that two species competing for the same limiting resource cannot coexist indefinitely is known as what?

• A. Shared resources principle
• B. Resource partitioning
• C. Niche differentiation
• D. Competitive exclusion

Answer: (D)

The main idea is competitive exclusion: when two species rely on the same limiting resource, they cannot coexist indefinitely. One species is better at using that resource or reproducing under those conditions, so it will outcompete the other and drive it out of the community or push it to shift to a different resource use. This is why you don’t see two identical competitors living in the exact same niche forever.

Resource partitioning and niche differentiation describe ways species can coexist by using different resources or occupying different ecological roles, reducing competition. They are mechanisms that enable coexistence, not the principle that limits it. Shared resources principle isn’t a standard term for this concept.

A classic demonstration of competitive exclusion comes from early studies showing that, in a shared environment with the same resources, one species outcompetes the other; but when species divide resources or occupy different niches, both can persist.