Question

Which one or more of the following reasons has/have been invoked to explain island gigantism?

• A. Absence of interspecific competitors
• B. Absence of predators
• C. Limited habitat
• D. Limited prey base

Hint:

Island gigantism occurs when ecological pressures like the absence of predators and competition, along with limited prey, lead to an increase in body size for certain species.

Answer 1

The Correct Option is A, B

Step 1: Understanding island gigantism.
Island gigantism refers to the phenomenon where certain species, especially animals, grow larger on islands than their mainland counterparts. This is often attributed to ecological factors such as the absence of predators, limited competition, and available resources.

Step 2: Explanation of each option.
(A) Absence of interspecific competitors allows a species to dominate its niche, leading to larger body sizes due to the absence of competition.
(B) Absence of predators means the species does not need to stay small to avoid predation, which can lead to an increase in body size.
(C) Limited habitat is not typically associated with gigantism, as species with limited habitat tend to be smaller.
(D) Limited prey base leads to selection for larger body sizes in some cases, as larger individuals may be more capable of obtaining food.

Step 3: Conclusion.
The correct answers are (A) and (B) because these factors are commonly invoked to explain island gigantism.