The graphs below depict the number of individuals of two organisms, named P and Q, when grown independently, and together. Based on these growth patterns, which one of the following statements is correct?
Show Hint
In ecological interaction graphs:
If one species dies out completely in the presence of another while both can live fine alone, it indicates either competitive exclusion or intense predation.
Since "competition" is not in the options, "Q is a predator of P" is the most logical answer as the predator eats up the entire prey population in a closed system.
Step 1: Understanding the Concept:
Population growth curves help determine the nature of ecological interactions (predation, competition, symbiosis). Step 2: Detailed Explanation:
$\bullet$ Independent Growth: Both P and Q show typical sigmoidal (logistic) growth curves when alone, meaning they can survive independently.
$\bullet$ Mixed Growth: When grown together, Q's population grows successfully to its carrying capacity, whereas P's population initially rises slightly and then crashes rapidly to zero (extinction).
$\bullet$ Reasoning: The complete elimination of P in the presence of Q indicates that Q is either an extremely efficient competitor or a predator that consumes all of P. In predation, the predator (Q) thrives while the prey (P) is eliminated in a closed system.
$\bullet$ Mutualism (+/+) is ruled out because P dies. Commensalism (+/0) is ruled out because P is negatively affected. Parasitism (+/-) usually doesn't involve the immediate extinction of the host if the parasite is to survive. Step 3: Final Answer:
The crash of P's population while Q thrives suggests that Q is a predator of P.
This corresponds to option (A).
