, Stanford ecologist Paul Ehrlich proposed the 'rivet popper hypothesis' to explain the impact of species loss . In this analogy, an airplane represents the ecosystem, and the thousands of rivets holding the plane together represent the various species . The hypothesis suggests that while losing a single rivet (an extinction) might not initially threaten 'flight safety' (ecosystem functioning), the continued removal of rivets eventually makes the plane dangerously weak . Furthermore, the loss of rivets on the wings is compared to the loss of key species that drive major ecosystem functions, posing a much more immediate and serious threat .