Australia is a land like no other, with about one million different native species. More than 80 per cent of the country’s flowering plants, mammals, reptiles and frogs are unique to Australia, along with most of its freshwater fish and almost half of its birds.

The distribution of both flora and fauna within a geographic range will depend on a number of related factors, including microclimate, predation pressure, competition, habitat structure and the distribution of resources including food, water and mates etc.

Evolutionary isolation and other geographical factors are responsible for unique flora and fauna of Australia.

Evolutionary isolation

• Australia has a unique flora and fauna because it was isolated from the rest of the world for very long periods.
• The Australian continent was surrounded by ocean for many millions of years, and so the plants and animals on that very large life-raft were able to evolve in distinctive ways.

Geographical factors

• Isolated Location: Tropic of Capricorn divides Australia into two almost equal parts. It has effects of tropical, subtropical as well as temperate climatic effects. It is surrounded by Ocean from all the sides.
• Tectonic stability: This has ensured any large scale destruction of flora and fauna.
• Unique Topography: Australia is divided into three major physical parts viz Eastern highlands, central low lands and western plateau.
• Diverse climatic features: Mostly desert or semi-arid in west and central parts of the country, south-east and south-west corners are temperate, whereas northern parts have tropical climate, varied between tropical rainforests, grasslands, part desert.
• Varying Rainfall: Due to unique topography and location, rainfall distribution varies throughout the Australian land. Eastern, north eastern and south western parts of the country comes in the way of rain bearing winds, thus receive heavy rainfall. Eastern high lands acts as a barrier to these winds, thus very large parts of western and central Australia have scanty or no rainfall at all.

Conclusion

• Due to such geographic uniqueness and evolutionary isolation, Australia became home to very unique flora and fauna, which includes largest number of marsupials and venomous snakes.

When animals and plants evolve in isolation they can become more vulnerable to novel predators or pathogens, this is one of the reasons Australia is so vigilant about quarantines and making sure they keep certain pathogens and invasive species out of the country.

Cane toads and rabbits are an example of invasive species gone amuck in Australia.

Aboriginals of Australia also played an important role in preservation and conservation of country’s unique flora and fauna.