Ecological Reasons

All organisms are interdependent. The removal of one organism can have a significant effect on the other organism in the ecosystem. If a food source or habitat is lost.Plants rely on bees for pollination. Fruit farmers rely on bees to pollinate their crops. A decrease in the bee population would decrease crop yields.A keystone species, despite having a relatively low population, has a disproportionately large impact on the ecosystem.When this species is removed, the habitat drastically changes. An example is the extermination of grey wolves in Yellowstone National Park by 1924. This caused the elk population to grow rapidly. The elk heavily overgrazed young aspen and willow trees which decreased the local beaver populations, destabilised riverbanks, and degraded the ecosystem. Wolves were reintroduced in 1995.