Evolution of Australian Environments due to.. Biological Isolation Geological stability Climatic variations

Gondwana Supercontinent in the southern hemisphere Made up of 7 countries

Australia's Separation from Gondwana 50,000 million years ago Last separated from Antarctica Travelled Northwards Australia became an island

What evidence that Australia was connected to Gondwana? 1. Shape of the continents – fit together like a jigsaw puzzle 2. Glossopteris Fossils – it was a woody, seed bearing shrub or tree

Biological Isolation Geological Stability Climatic Variations Three (3) Characteristics that have shaped Australia’s outdoor environment Biological Isolation Geological Stability Climatic Variations

Biological Isolation

What is it?? Biological Isolation refers to when living species (flora and fauna) have evolved without contact or influences form other species. With Australia being an island, Australia’s unique native species have evolved without other countries influence Biological Isolation occurred when Australia split from Gondwana to form its own land form in isolation.

Biological isolation Charles Darwin’s theory was that species change over time, or evolve in response to the environment. This is basically what biological isolation is; the change of species over time by being isolated from one another.

Specific examples Platytpus Large water rats were around in the Gondwana period. When Australia split from the larger sections of Gondwana, water rats in Australia where left without diversity in their breeding partners. As suggested by Charles Darwin, biological isolation resulted in the water rats in Australia forming into their own species, as we know as the platypus.

Specific examples Australian Marsupial Animals KANGAROO - How did it evolve??

Geological Stability

What is it? Australia has been without volcanic activity or movement for many years due to being located relatively in the center of the Indo-Australian tectonic plate. The last volcanoes on the continent of Australia were active many years ago compared with other continents. This, combined with very little geological activity (earthquakes), has led to Australia’s soil being old and poor quality (low in nutrients). The state of the soils has had an influence on the Australian flora as those who were unable to adapt were also unable to survive.

Geological stability Australia has low tectonic, volcanic and glacial activity. There are few mountain ranges and the landscape is generally flat, making it prone to floods and erosion, and therefore affecting the survival of flora and fauna. What flora species have adapted to Australia’s poor soil?

Australia’s Eucalyptus Tree Adapted by developing deep root systems penetrating the top poor soil.

Climatic Variations

What is it? Australia experiences a relatively erratic climate in comparison to other continents of the world. There seems to be two main extremes, long, lean droughts in El Niño years and flooding rains in La Nina years These periods can last anywhere from 1 – 10 years, this low level of predictability has had an impact on the adaptability and diversity of flora and fauna. The Australian climate varies on longer time- scales, over decades and centuries. What is El Nino and La Nina?

Flora releasing seeds after a fire Banksia (pictured) is a common species to have developed this trait along with the Australian Mountain Ash These have evolved uniquely due to poor Australian soils. Fire indicates the release of nutrients from burnt materials which is ideal conditions for the growth of new seedlings. Basically reducing wasted seeds due to being released onto soils with minimal nutrients.

Questions What adaptions would plants need to make to deal with poor soil quality and erratic climate? How has Australia’s animals adapted to our harsh and changing climate?

Adaptions to Australia’s erratic climate and soil quality Plants Hard, glossy leaves resist water loss through transpiration Evergreens reduce energy usage Long, narrow leaves that hang vertically presenting small surface area to sun Small leaves, or none Dormancy Deeper root system Animals Water storage Metabolic adaptations to minimise water loss Energy efficient movement – eg. hopping Energy saving adaptations – eg. Koala’s brain

Facts about Australia’s uniqueness High fire rates Highly erratic climate Susceptible to extended periods of drought Highly isolated (We’re on an island!) Large amount of uniquely native species (compared to the rest of the world) Unique flora and fauna adapted to landscape Relatively flat continent Unique flora and fauna adapted to climatic conditions Low soil quality (low in phosphorus which allows for extensive plant growth) Why are we unique? Biological Isolation Geological stability Climatic variations

Facts about Australia’s uniqueness High fire rates Highly erratic climate Susceptible to extended periods of drought World’s 6th Largest Island Large amount of uniquely native species (compared to the rest of the world) Unique flora and fauna adapted to landscape Relatively flat continent Unique flora and fauna adapted to climatic conditions Low soil quality (low in phosphorus which allows for extensive plant growth) Why? Biological Isolation Geological stability Climatic variations