Question

In the figure below, ellipse X represents the combinations of salt concentrations and temperatures that a marine invertebrate species can tolerate. Ellipse Y represents the combinations of salt concentrations and temperatures that this species is actually found in.Which one or more of the following statements about X and Y is/are correct?

• A. X is the fundamental niche of the species, whereas Y is the realized niche.
• B. The difference between X and Y can result from biotic interactions.
• C. The difference between X and Y can result from dispersal limitation.
• D. The difference between X and Y results from the species’ tolerance to salt concentrations

Hint:

Natural selection requires \emph{heritability} and \emph{fitness advantage}. Universality (all showing the trait) or specific modes of transmission (only parents teaching) are not required.

Answer 1

The Correct Option is A, B, C

Step 1: Define terms.
- The \emph{fundamental niche} is the full set of environmental conditions a species can tolerate in the absence of limiting biotic interactions. - The \emph{realized niche} is the subset of conditions where the species actually occurs, limited by competition, predation, mutualisms, and dispersal.

Step 2: Evaluate options.
(A) \emph{X is fundamental, Y is realized.}
Correct — ellipse X shows potential tolerance, while Y shows actual occurrence. (B) \emph{Difference due to biotic interactions.}
Correct — competition, predation, or facilitation can prevent species from occupying its entire physiological range. (C) \emph{Difference due to dispersal limitation.}
Correct — even if conditions are suitable (inside X), the species may not reach those sites, restricting Y further. (D) \emph{Difference due to tolerance to salt.}
Incorrect — tolerance defines X itself (physiological limits). The gap between X and Y is not due to tolerance but due to external factors (biotic or dispersal).

Step 3: Conclusion.
Thus, the correct set of explanations are (A), (B), and (C). Final Answer:\quad \(\boxed{\text{(A), (B), and (C)}}\)