The separation of the Australian continent from other landmasses following the gradual breakup of the Gondwana supercontinent about 140 million years ago, has provided the Australian flora and fauna a rare opportunity to evolve in isolation for at least the past 50 million years. Australia's numerous climactic zones and varied habitats have given rise to an enormous diversity of species.
Many Australian species are unlike any other plants and animals elsewhere.
Species extinction has accelerated following European settlement. The last 200 years has seen a dramatic change in Australia's natural ecosystems. For instance, a wide range of exotic plants and animals were introduced, many of which have become weeds and destructive pests, causing widespread ecological problems at an unprecedented rate and scale. A third of all recorded world extinction of mammals this century have occurred in Australia. Moreover, there are more threatened species of amphibians and reptiles in Australia than in any other country.