Which statement correctly describes the fundamental niche and the realized niche?

• A. Fundamental niche is the range of resources actually used by the species.
• B. Realized niche is the full potential range of conditions.
• C. Fundamental niche is the full range of environmental conditions under which a species can survive and reproduce.
• D. Realized niche is the population size.

Answer: (C)

The key idea is distinguishing potential tolerance from actual occupation. The fundamental niche represents the full range of environmental conditions under which a species can survive and reproduce, in the absence of limiting biotic interactions. It’s like the entire space the species could potentially inhabit if there were no competitors, predators, or other pressures. The realized niche, on the other hand, is the subset of that space that the species actually uses in the real world, shaped by interactions with other organisms and resource limits. That’s why the statement describing the fundamental niche as the full range of environmental conditions under which a species can survive and reproduce is correct. The other options mix up these concepts or tie niche to population size, which isn’t what niche describes.