B9 - Quaternary biogeography

Question 1

How many major glaciations were there during the Pleistocene?

Answer 1

5-6 major continental glaciations and ca. 16 periods of less extensive ones

Question 2

Explain eustatic changes in sea level

Answer 2

Eustatic changes are global fluctuations in sea level resulting from changes in the volume of water in the oceans, such as those resulting from the locking up or release of massive amounts of water in major ice sheets.

Question 3

Explain isostatic changes in sea level

Answer 3

Isostatic changes in sea level occur when portions of the Earth’s crust rise or sink into the less boyant asthenosphere (the depth in the earth where heat from the core begins to melt the crust.), causing local or relative changes in sea level even when eustatic levels remain unchanged.

Question 4

What is a biota?

Answer 4

The animal and plant life of a particular region, habitat, or geological period

Question 5

There were three fundamental changes to the environments of the Pleistocene bioatas due to the climate cycles of the time (glacial and interglacial periods), which triggered their biogeographic dynamics, what were these changes?

Answer 5

1. Changes to the location, extent and configuration of their prime habitats
2. Changes in the nature of climatic and environmental zones
3. Formation and dissolution of dispersal routes

Question 6

What were the responses of the Pleistocene biotas to the fundamental changes in their environments due to the climate cycles of the time (glacial and interglacial periods)?

Answer 6

1. Some species were able to “float” with their optimal habitats as it shifted geographically or in elevation
2. Other species remained where they were and adapted to altered local environments
3. Still other species underwent range reduction and eventual extinction