Earth Sciences 2240F/G Chapter Notes - Chapter Unit 4: Phanerozoic, Outer Core, Holocene Extinction
13 Feb 2018
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Unit 4 intro: the geological time scale; potential causes of mass extinctions. Biodiversity: the variation of life forms w/in a given ecosystem or on the entire earth. Often discussed w/ the health of an ecosystem. Biodiversity in desert regions (hot or cold) is limited when compared to that of the tropics. Any rapid environmental change in regions of limited biodiversity will likely promote species extinction. Extinction: the end of an organism or group. We define the last death by projection of population decline. Background extinctions: extinctions caused by moderate environmental changes or normal biological interactions. Occur routinely all the time because of small changes in the environment, climate/habitat, lack of resources, or by inter-species competition. ~99. 9% of all species to ever exist are now extinct: species become extinct when they are no longer able to adapt to changes in the environment or against superior species competition.
