(N/A) The 'rivet popper hypothesis' was proposed by Paul Ehrlich to explain the importance of species diversity in an ecosystem.
$1$. He compared an ecosystem to an airplane and the species within it to the 'rivets' holding the airplane together.
$2$. If every passenger starts popping a rivet to take home as a souvenir,the flight safety is initially not affected.
$3$. However,as more and more rivets are removed,the plane becomes dangerously weak over a period of time.
$4$. Similarly,the loss of a few species may not immediately affect the ecosystem,but the loss of key species (critical rivets) can cause a major collapse of the ecosystem.