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| Description: Canadian Species at Risk Act uses categorizes: Extinction = occurs when the last member of a species dies and the species ceases to exist Extirpation = the disappearance of a particular population from a given area, but not the entire species globally Endangered = species in imminent danger of becoming extirpated or extinct Threatened = species likely to become endangered in the near future Paleontologists estimate 99% of all species that ever lived are now extinct Background rate of extinction = natural extinctions for a variety of reasons 1 species out of 1,000 mammal and marine species would go extinct every 1,000 to 10,000 years 1 extinction per 1 to 10 million species for mammals and marine species Earth has experienced five previous mass extinction episodes In the past 440 million years, mass extinctions have eliminated at least 50% of all species Today’s mass extinction is caused by humans and humans will suffer as a result of it Picture Stats: Views: 276 Filesize: 49.28kB Height: 504 Width: 786 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=35765 |