Part of the Evolution of Australian Biota Module Biology in Focus, Preliminary Course Glenda Childrawi and Stephanie Hollis Evolution of Australian Biota Topic 5: The Evolution of Australian Flora and Fauna

DOT Points Identify and describe evidence of changing environments in Australia over millions of years Identify areas within Australia that experiences significant variations in temperature and water availability

Evidence for Changing Climate The traditional way to infer changes of climate is from geological structures. If rocks show evidence of ripple marks, you know there was water. If they are covered in striations, they show evidence of glaciers. nsidc.org en.wikipedia.org

Evidence for Changing Climate Another traditional way to infer climate is from fossils present in rocks. Coral will only grow in warm, clean water so limestone is evidence for rocks formed in low-latitude regions (near the equator). posters.co.uk

Evidence for Changing Climate Plants do not move, so they provide good indicators of climate in an area. Finding fossilised plants like conifers that grow in cooler areas and ferns that grow in moist conditions tell us a lot about the area. Tree rings can indicate climate on a year by year basis. sciencephoto.com blog.drwile.com

Evidence for Changing Climate Modern technology that can measure magnetism and radioactivity has been put to use in determining past climates. Magnetic patterns left in rocks provide evidence for plate tectonics and these patterns on land have allowed the movement of continents to be plotted. volcano.oregonstate.edu

Evidence for Changing Climate The ratio isotopes of O-16/O-18 in a fossil, such as a shell, can be used to deduce temperatures of the time. Under warm conditions the O-16/O-18 ratio is high, and under cold conditions it is lower. This technique has also been applied to ice cores from glaciers. earthobservatory.nasa.gov woodcollection.com

Evidence for Changing Climate These techniques can be used to infer what the Australian climate was like in the past and how it has changed. We can then deduce information about flora and fauna including how and why organisms have evolved or become extinct. racvarela.blogspot.com

The Drying of Australia As Australia drifted northward, it moved through different climactic zones. Around 30 million years ago, it lay in the belt of moisture of westerly laden winds as Tasmania and New Zealand do today. (glue Figure 7.22 into books) Fig 7.22 Spotlight text pg 176 smh.com.au

The Drying of Australia Temperate rainforests spread across the eastern and southern parts of the continent and Central Australia was covered in grasslands. The northern tip had started to enter the dry mid-latitudes- the zone where deserts form. spaceinfo.com.au

The Drying of Australia Around 25 million years ago the continent was a mix of temperate rainforest and extensive grassland. Under these ideal conditions a great diversity of marsupials developed, however, the gradual drying of the continent as it entered the subtropical zone contributed to the extinction of many of these marsupials, especially the megafauna. wildtracks.wordpress.com

The Drying of Australia Our knowledge of changes in plant and animal distribution is more extensive for the last years or so. This was during our last global period and part of Australia was very cold and large sections were desert. (Glue Figure 7.23 into your notebooks) Diagram (a) Figure 7.23 spotlight text pg 177 anaspides.net

The Drying of Australia Pollen records show that Callitris, Acacia and Casuarina woodlands occupied the Great Dividing Range, there were now forests. The south-eastern corner was very cold, alpine vegetation or cold grasslands spread right down the coast. anaspides.net

The Drying of Australia Around years ago the glaciation started to recede and sea levels rose, cutting off access between the first mainland Tasmania and then the mainland and New Guinea. A warming of the oceans saw significant increase in rainfall and a significant change in vegetation. A pattern almost the same as today resulted. Diagram (b) Figure 7.23 spotlight text pg 177 anaspides.net

The Drying of Australia Forests reinvaded the Great Dividing Range so that Callitris, Acacia and Casuarina woodlands are not restricted to a few remnant pockets. When white settlers arrived 200 years ago, the Australian flora and fauna were recovering from this very dry period. flickr.com

The Drying of Australia The Indigenous Australians were present and used firestick farming as part of their survival strategy. This use of fire has also altered the distribution and abundance of flora and fauna. treatyrepublic.net

Australia’s Unique Flora Modern-day flora is very different from that on other continents, with many species found exclusively in Australia. The familiar Australian native species such as wattles, eucalypts, banksias and she- oaks all possess adaptations that allow them to thrive in soils that are nutrient poor, areas that are arid and where fire is common. brouleesurfschool.com.au

Australia’s Unique Fauna Australia has a wide variety of marsupial fauna today, including bandicoots, Tasmanian devils, koalas, wallabies and kangaroos. Most living marsupials today are found in Australia and only a few exist in South America. endangered-animals.com.au

Australia’s Unique Fauna There is ongoing debate as to what led to the changes in the Australian flora and fauna, in particular the extinction of the megafauna. australianmuseum.net.au

Activity -Students to complete 1.5.1a Timeline Changes in Australia