Two species that possess the same ecological niche cannot coexist indefinitely. This is known as the

I. competitive exclusion principle
II. Gause's principle of competitive exclusion
III. principle of character displacement
IV. principle of self-assembly

Which of the above is/are correct?

The statement describes the Competitive Exclusion Principle, which is also widely known as Gause's principle of competitive exclusion (named after Russian microbiologist G.F. Gause). The principle states that two species competing for the same limiting resources cannot coexist indefinitely in the same ecological niche; the more efficient competitor will eventually eliminate the other.

• Principle of Character Displacement: This refers to the evolutionary process where two similar species develop divergent traits to reduce competition (niche partitioning), which actually enables coexistence rather than preventing it.
• Principle of Self-assembly: This is a concept primarily used in chemistry and biology to describe how disordered components form organized structures through local interactions, unrelated to ecological niche competition.

Therefore, both I and II are correct names for the described phenomenon.