Which of the following compares an ecosystem to an airplane and says…

The correct answer is Option (4) → Rivet popper hypothesis

To explain why the loss of species matters, Stanford ecologist Paul Ehrlich used an analogy called the ‘rivet popper hypothesis’. An airplane (the ecosystem) is held together by thousands of rivets (the species). Popping a few rivets may not affect flight safety at first, but as more are removed the plane becomes dangerously weak, and losing rivets on the wings (key species) is more serious than losing those on the seats.

Option (1) Competitive exclusion principle — Incorrect. The competitive exclusion principle of Gause says that two closely related species competing for the same resources cannot co-exist indefinitely. It is about competition, not an airplane model.

Option (2) Resource partitioning — Incorrect. Resource partitioning is the way competing species avoid competition, for example warblers feeding in different parts of the same tree. It has nothing to do with rivets.

Option (3) Species-area relationship — Incorrect. The species-area relationship, observed by Humboldt, links species richness with the area explored. It is a graph and an equation, not an analogy.

Option (4) Rivet popper hypothesis — Correct. The rivet popper hypothesis compares the ecosystem to an airplane and the species to its rivets.

NCERT Extract:
The Importance of Species Diversity to the Ecosystem – “… There are no direct answers to such näive questions but we can develop a proper perspective through an analogy (the ‘rivet popper hypothesis’) used by Stanford ecologist Paul Ehrlich. In an airplane (ecosystem) all parts are joined together using thousands of rivets (species). If every passenger travelling in it starts popping a rivet to take home (causing a species to become extinct), it may not affect flight safety (proper functioning of the ecosystem) initially, but as more and more rivets are removed, the plane becomes dangerously weak over a period of time.”