4.1.4 Extinction

Question 1

Extinction causes

Answer 1

Environmental change
e.g. introduction of disease, competitors or predators ; climate change, habitat loss

Question 2

Background extinction

Answer 2

Species evolve and species become extinct (mya) - this process takes time, over millions of year

Question 3

Mass extinction

Answer 3

A large number of species of species become extinct in a small time frame, often in response to a specific environmental factor.
e.g. dinosaurs became extinct due to a meteorite strike 65mya

Question 4

Case Study - the Australian Thylacine (Tasmanian Tiger)

Answer 4

An example of mass extinction (occurred quickly), becoming extinct in the last century due to human intervention:
- hunted to extinction <- preyed on sheep
- competition with dingoes
- taken by zoos when perceived as rare, died in captivity.

Question 5

Theories of Extinction 1: Changes in climate (the continent dried out from most recent ice age.

Answer 5

For:
- Megafauna depended on supplies of water
- Producers became more scarce

Against:
- There have been ice ages before this extinction
- The megafauna extinction seemed to have peaked before the beginning of the last ice age
- Current climate change does not seem to select against large, slow moving animals.

Question 6

Theory 2: Arrival of Humans

Answer 6

For:
- Archaeological evidence for the arrival of Aboriginal people coincides with the end of the Australian megafauna

Against:
- There is no evidence of kill sites, and very little evidence of humans and Megafauna living together.