Biogeography Chapter 9
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Climate in the Pleistocene
Climatic zones shifted toward the equator during glacial periods and back towards the poles during interglacial periods
Glaciation during the Pleistocene
Glacial winters were less severe, although summers were much cooler. The weight of glaciers can push the land down by hundreds of meters and the land can rebound when glaciers melt, resulting in isostatic changes.
isostatic- refer to the state of gravitational equilibrium between the earth's lithosphere and asthenosphere such that the tectonic plates "float" at an elevation which depends on their thickness and density.
Sea Level in the Pleistocene
Water gets trapped in glaciers and is lost to oceans.
Biogeographic consequences of glaciations
- Vertical and latitude shifts
- Refugia- centers of endenism. Plants/animals aren't subject to speciation and are trapped (isolated population)
- Barriers of bridges- create vicariant barrier for marine organisms
- Aquatic and Bridges- Vicariant separations of land masses creates a habitat bridge for marine animals
- Extinct: Large land animals- Giant sloths, Saber-toothed cats, mammoths, marsupial lions, short faced kangaroos
- Survived: Small land animals, ground sloths
How did the Pleistocene extinction vary from continent to continent?
Most megafauna went extinct, with the exception of Africa
What caused Pleistocene extinctions?
- Overchill:Climate change as a result of asteroids or vegetation change
- Overkill:Humans resulting in fires, competition, and/or hunting.
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