Extinction and Habitat Tracking during the Pleistocene

The expansion and contraction of the major ice sheets and mountain glaciers reflected the glacial (cold) and interglacial (warm) episodes that also caused habitats to contract and expand. These cooling and warming episodes forced species to migrate and adapt in response to environmental changes. For example, tropical fauna such as lions and elephants inhabited Trafalgar Square in central London; these organisms are now confined to tropical Africa.

The Pleistocene extinctions affected many large (greater than 40 kg) mammals in North America (73 percent: 33/45 genera lost); South America (80 percent: 46/58 genera lost); and Australia (94 percent: 15/16 genera lost). Europe and southern Africa suffered the fewest extinctions (5 percent: 2/44 genera lost). Two main hypotheses explain the pattern of extinction for the end-Pleistocene. The prehistoric kill hypothesis suggests that large mammals became extinct because of overhunting by humans. This is based on the coincidence of human arrivals with mass extinctions in North and South America and Australia, as well as a number of kill sites where human artifacts are associated with large mammal remains. Rapid climate changes near the end of Northern Hemisphere glaciation are also suggested as a mechanism for extinction, because of the rapid shifts from colder climate, open-grassland tun dra to warmer, wetter-climate conifer-broadleaf forests during the latest Pleistocene.

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