Question

Species 1 and 2 belong to the same genus and co-occur at the same site. Which one or more of the following strategies would facilitate their coexistence at the site?

• A. Species 1 has high frequency calls, Species 2 has low frequency calls
• B. Species 1 and 2 specialise on the same limited resource
• C. Species 1 nests near the ground, Species 2 nests in the canopy
• D. Species 1 and 2 breed at different times of the year

Hint:

Coexistence between close relatives is easier when they divide up a resource, a habitat, a signal channel, or a time window instead of competing head to head for the identical thing.

Answer 1

The Correct Option is A, C, D

Step 1: Recall why closely related species struggle to coexist.
Two species in the same genus usually have very similar needs, so when they live at the same site they tend to compete strongly for food, space, mates, and other resources. The competitive exclusion principle says two species cannot persist indefinitely on exactly the same limiting resource in exactly the same way; one will eventually outcompete the other. Coexistence becomes possible only when the species divide up their niches so they are not competing head to head.

Step 2: Check option (A).
If Species 1 calls at a high frequency and Species 2 calls at a low frequency, their acoustic signals do not overlap. This keeps their mating calls from interfering with each other and lets both species communicate without confusing the other. This is niche partitioning through the signal channel, so it helps coexistence. Option (A) is correct.

Step 3: Check option (B).
If both species specialise on the same limited resource, they place maximum demand on the identical thing at the identical time. There is no partitioning at all here, so this is exactly the situation the competitive exclusion principle predicts cannot last. This works against coexistence. Option (B) is incorrect.

Step 4: Check option (C).
If Species 1 nests near the ground and Species 2 nests in the canopy, the two species use different physical space within the same site. This spatial niche partitioning reduces direct competition for nest sites and reduces contact between the species. Option (C) is correct.

Step 5: Check option (D).
If the two species breed at different times of the year, they are separated in time even while sharing the same site. This temporal partitioning means their demand for breeding resources, such as mates, nest sites, or food for young, never peaks at the same moment. Option (D) is correct.

Step 6: Final answer.
Coexistence is helped by dividing up the acoustic channel, the nesting space, and the breeding season, but is hurt by both species chasing the identical resource in the identical way.
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