Answer:
b. Two species that use a limited resource in the same way cannot coexist indefinitely
Explanation:
The competitive exclusion principle establishes that two or more species that share the same niche requirements, in the same habitat, and are in biological competition for the same resources, won´t be able to coexist indefinitely in the same space if the other ecological factors are constant. This is because species with identical niches have the same necessities, which means that they will compete for the same resources. If these species have the same requirements, they can not coexist. When the superior competitor occupies the inferior competitor´s fundamental niche, the first species has advantages over the second species and <em>monopolizes all the resources</em>. From that moment, the inferior species is displaced and must adapt to use other resources changing its behavior, or must migrate to another area where it can get access to its needs or get extinct.
When <em>two competing species coexist</em>, this is because of niche partitioning or niche differentiation. One of the species uses a <em>different resource, occupies another area, or uses the resources at different times during the day</em>. If there is not any differentiation between them, the dominant species displaces the weak species.
Niche specialization might produce genotypic separation. Subpopulations of a species diverge into new species.
So, <em>competitive exclusion refers to the exclusion of the inferior competitor by the superior competitor when there is not habitat differentiation, and both species can not share the same niche. </em>
