Final Reflections

Question 1

Biogeographic context for Australian biodiversity

Answer 1

Australia was once part of Gondwanaland, connected to Antarctica, South America, Africa, India..

130 Mio years ago initial separation of continents from the supercontinent.

Australia remained isolated for tens of millions of years up to the point where it hit South East Asia ~15 million years ago.

Biotic interchange between Sunda (SE Asia) and Sahul (Australia).

This means that Australia has species that have been here for a VERY long time and species that have arrived fairly recently. (Taxa evolved from Gondwanan ancestors and species that arrived through land bridges via Sunda or ocean immigration)

Question 2

The two main processes that facilitate the development of new species (both termed allopatric speciation)

Answer 2

Vicariance and dispersal

Vicariance: a species can be geographically separated and evolve two separate species (River suddenly appears down the middle)

Dispersal: Individuals from one species migrates to another area and evolves into separate species.

Question 3

How has biodiversity been affected by climate?

Answer 3

Changes in climate coincide with shifts in tectonic plates and the northwards movement of Australia.

Cool and dry to warm and wet (oscillated back and forth a couple of times) affected the evolution of different Australian plant species and their reliant animal taxa.

Question 4

Changes in dominant vegetation type of Australia over time (from 45 Mio years ago moving forward)

Answer 4

Nothofagus (Southern Beech, Gondwana trees)

Rainforest (more southern pines, nothofagus, araucareans)

Myrtaceae (eucalyptus)(Precipitation decline, fire increase)

Wet sclerophyll forests

Rainforest

Question 5

Processes that maintain diversity

Answer 5

Stable climates and habitats

Natural disturbances (fire)

Ecosystem engineers (a single taxa can have a really important role)

Species relationships

Question 6

Diversity erosion

Answer 6

(Biodiversity erosion started in Australia with the mega fauna extinction during the Pleistocene)

Diseases (chytridiomycisis in frogs)

Invasive species

Habitat loss and fragmentation

Climate change