ENV200H1 Lecture Notes - Wildlife Smuggling, Passenger Pigeon, Endangered Species
Document Summary
Extinction: death of a life form, natural event, fate of all species, 99% of all previous species are extinct, currently accelerated by human activities. Species at risk: extinct: no longer present anywhere, extirpated species: no longer present in wild, endangered species. High probability of becoming endangered: special concern. Not in serious danger, but sensitive to human activities: genetic variability severely diminished. Increasing wealth (based on exploiting the env) is generating demands on the env that cannot continue to be met. In the poorer regions of the world poverty forces ppl to adopt subsistence living (ex: deforestation and overgrazing) that destroys critical habitat for other species. Human causes of species endangerment: habitat loss, pollution, overexploitation. Habitat loss: largest threat to species, destruction, fragmentation, degradation. As we fragment habitat, we leave small islands of undisturbed habitats in a sea of disturbance. Mac arthur and wilson"s theory of island biogeography: 1. Distant islands support fewer species than near shore islands (distance effect: 2.
