Biogeography
Isolation has played a key role
in the development of plant and animal species in Australia. Oddly developed animals
like the large marsupials (e.g. kangaroos and wallabies) and the duck-billed platypus
represent what evolution will do when animal species morph to fill niches in the environment. The
greatest of ecosystems - communities of plants and animals coexisting in a
particular physical environment - is the Great Barrier Reef off the northeast coast of
Australia. Made of living coral polyps, it is the most diverse underwater reef in the world.
-Exotic Species,
Extinction and Environmental Change-
The changes wrought on
the environment by the Europeans were immediate, powerful, and lasting.
• Forests: 35% cleared,
3/4 of the rainforest destroyed; the results are soil erosion and a rise in
the water table, with increasing soil salinity (saltiness)
• Feral species: horse, camel (the largest
population in the world), goat, pig, donkey, water buffalo and house cat; the worst
is the fox (introduced by sportsmen) that is an aggressive predator and the hares that dig
burrows which hasten desertification; dingoes (introduced 3500 years ago) and the Dog Fence which stretches 3,300
miles across Australia protecting the sheep herds in the south
•
Other introduced species: mollusks and seaweed came in the ballast
water of ships; sugarcane, cane beetles, and cane toads (which produce
toxins that kill unwary predators)
•
Extinction: certain emu sub-species, some bandicoot species, select
wallaby species, and desert rat kangaroo are forever extinct