Topics 2 and 3 - Biogeography and Current Distributions

What is Biogeography?

The study of where species are found and why. Includes both space (global to local) and time (historical biogeography). Basically involves looking at diversity patterns and trying to explain them. Scale is important.

What is Historical Geography?

We can use genetics to understand historical geography. This is called phylogeography.

How did Australia get its Unique Diversity?

1. Through History

2. Current Environments

3. Human Impacts

Through History

1. A supercontinent called Pangea was formed with some groups of organisms we see today (200 mya)

2. Pangea began to break up and most groups of organisms are now alive (150 mya)

3. Continents drift and form their own continent, however, Australia, South America, and Antarctica are still connected (90 mya)

4. Australia has broken off and is isolate, however, as it drifts more north, its forest get drier and drier, forcing organisms that rely on this habitat to diversify in isolation (50 mya)

5. Australia is now reaching its position we see today, and New Guinea is starting to form/drift away from Australia, and Australia and Asia are now contacting. Australia is also very dry, giving way to deserts instead of forests (15 mya)

6. The Pleistocene Glacial Period occurred and would’ve dried up many parts of the world (2 mya)

This is why we see links in species and habitats between Australia, New Guinea, and South America.

Current Envrionments

Abiotic:

• climate can determine the type of habitat that forms

• topography generates moisture and cooler areas

• topography also generates many features such as valleys and also rocky environments which are fire proof

• barriers can create habitat specialization, reflect movement abilities, etc

Biotic:

• Species interactions (like competition)

Human Impacts

We modify fire, clear areas, introduce new species, hunting (such as no more quolls in the Paluma range), etc.