4.2 Changes in Australian Flora and Fauna Questions and Answers

4.2 Changes in Australian flora and fauna – Questions and answers

Q1.

Bk Ch4 S4.2 Q1

Use examples of an Australian animal and plant to illustrate that variation exists within populations of a species.

A1.

Bk Ch4 S4.2 A1

Variation exists between members of the same species. For example, different populations of the white-naped honeyeater that occur in Western Australia vary in the colour of eye-patch—some populations have a white eye-patch and others are characterised by a green eye-patch. Victoria’s common heath, Epacris impressa, can be found with crimson or white flowers or with intermediate varieties of pink.

Q2.

Bk Ch4 S4.2 Q2

aDescribe the changes that have occurred in the Australian climate over the last 65 million years. Explain why these climatic changes have occurred.

bAssess the impact of these climatic changes on plant communities, in terms of both distribution and vegetation type.

A2.

Bk Ch4 S4.2 A2

aWhen Australia was still joined to Antarctica around 65 million years ago the climate was cooler and wetter than it is now. Temperate rainforest covered much of the land. Once Australia became separated from Antarctica it began to move northward and as it did so its climate became warmer and drier. As the northern part of Australia moved into the Tropic of Capricorn the climate in this part of the continent became tropical.

bAs Australian climate became warmer and drier the temperate rainforests that once covered much of the land contracted to coastal regions. The vegetation type also changed with species developing that were more tolerant of higher temperatures and reduced water availability. These included more woody sclerophyll forests and grasslands.

Q3.

Bk Ch4 S4.2 Q3

Describe the evidence from Riversleigh in Queensland and Naracoorte in South Australia that demonstrate change in Australian ecosystems.

A3.

Bk Ch4 S4.2 A3

The kinds of organisms found at Riversleigh in Queensland suggest that the environment has changed from predominantly rainforest to a much drier habitat over the period from about 24 to 2 million years ago. At Naracoorte in South Australia the fossil evidence is a testimony to a change from an ecosystem of forests and inland lake ecosystems to one including open woodland over the last two million years.

Q4.

Bk Ch4 S4.2 Q4

Outline how Charles Darwin interpreted his observations of Australian flora and fauna in terms of his theory of evolution. Use specific examples to clarify your answer.

A4.

Bk Ch4 S4.2 A4

Darwin observed similarities between Australian species of organisms and more familiar organisms in Europe; for example, he likened the crow to an English jackdaw, a potoroo to a rabbit. He interpreted the likenesses as suggesting that the organisms were related. Of his observations that different kinds of organisms living in similar environments showed similar adaptations he suggested that such organisms must have become adapted to their particular habitats.

Q5.

Bk Ch4 S4.2 Q5

aDescribe Australian environmental conditions, identifying those areas that experience wide fluctuations in temperature and water availability.

bRelate the distribution of vegetation to temperature and rainfall patterns.

A5.

Bk Ch4 S4.2 A5

aAustralia is the driest of the world’s continents. While much of the northern and eastern sea borders experience average rainfall the interior of the land is largely desert. Seventy-five per cent of the Australian continent receives less than 800 mm of rainfall each year and that is often unreliable, especially in the interior and along the west coast. Extreme patterns of drought and flood are common. Australia is a mainly hot continent with cooler temperatures experienced only in the south-east and south-west. Dramatic temperature fluctuations are most pronounced in the interior where daytime temperatures reach over 40C and the heat escapes rapidly at night, and temperatures plummet.

bVegetation types vary across the continent with the changing climatic conditions. The richest and most abundant vegetation can be seen along the east coast where conditions are temperate with reliable year-round rainfall. This includes rainforests in the north, and forests and woodlands further south and inland. As temperatures increase and rainfall declines towards the interior, shrubland becomes more prominent. Only plants adapted to the arid conditions survive in the desert.

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