BIOL 102 Lecture Notes - Lecture 12: Ecological Pyramid, Introduced Species, Trophic Level
Document Summary
Endangered species act (esa): 1973 law passed to protect and encourage population growth of threatened and endangered species. Response to unprecedented and rapid rate of species loss. Background extinction rate: the rate at which species are lost through the normal evolutionary process. Current extinction rate: calculated from known species disappearances. Habitat: the place where a particular species lives and obtains resources for survival. Habitat destruction: natural landscapes decline and the number of species supported decreases. Species area curve: measures the relationship between the size of natural areas and the number of species supported. Estimates rates of extinction in regions rapidly changing due to human activity. At present rate of global habitat destruction, 25% of all species could become extinct with 50 years. Used to predict extinction caused by habitat destruction. Habitat fragmentation: large natural areas subdivided into smaller areas. More commonly caused by humans activity than complete habitat loss. This is because of how energy flows in an ecosystem.
