Globalization allows industries to move around to different countries to minimize costs and maximize productivity. Country X is really good at growing widgets for export. Country Y is really good at manufacturing thingamajigs for export. Et cetera. All very efficient and mutually beneficial, until country X depletes its resources, is unable to either produce widgets or purchase thingamajigs. Both country X and country Y go "belly up". A person living in country X really wants to pursue a career in thingamajig manufacturing because there just isn't any money in widgets anymore, but can't because he was unfortunately educated in widget farming, and underqualified to emigrate to country Y.

There is a squirrel in the northwestern US whose diet is so specialized that it can only survive in areas with lots of pine trees. If its natural habitat is destroyed it will become extinct. The pine trees also depend on the squirrel to bury some of its seeds. If the squirrel were hunted to extinction by a predator, the pine trees might also become extinct.