4.2.3 - Living evidence of ecosystem change

Question 1

Gondwana

Answer 1

Ancient super continent which included most of the land masses found in the Southern Hemisphere.

Australia fully separated from Antarctica 30 million years ago.

Question 2

Change of Australian climate after Gondwana separation.

Answer 2

Fossil evidence: dominated by tropical rainforest habitats

Change in weather patterns: increasing temperature, precipitation for seasonal. This led to long term changes to the arid environment today

Surviving pockets of rainforests (Gondwana Rainforests) contain species that evolved from early tropical Gondwanan species.

Question 3

Adaptation to changing ecosystems- sclerophyll plants

Answer 3

Characteristics: tough leaves containing toxic or indigestible chemicals, thus unpalatable to herbivores. Suited to harsh, dry climates

Originated 50-35 mya, but limited distribution due to widespread tropical climate.

Increased distribution with increase of charcoal deposits (fires from drier climate). Rainforest species only survived in pockets, thus eucalyptus and acacia increased in abundance by taking advantage of the new ecological niches.

Question 4

Adaptations to changing ecosystems - small mammals

Answer 4

Mammal distribution at its peak during rainforest.

Rainforest –> sclerophyll
Arboreal (tree dwelling) –> larger ground dwelling mammals.
* Arboreal species were restricted to pockets of rainforest

Question 5

Evolution of kangaroo species