Bi 6a 16 June 2010Biodiversity.ppt1

 the diversity of nature cannot support the current pressure that humanity is placing on the planet. ( human activity decreases biodiversity)  70% of coral reefs are threatened or destroyed.  18,788 species out of 52,017 so far assessed are threatened with extinction.  1,895 of the planet’s 6,285 amphibians are in danger of extinction, making them the most threatened group of species known to date. 16 June 2010Biodiversity.ppt2

 Deforestation -> forests are cut down for human use—ex. Agriculture, cattle- grazing, housing  Urbanization -> beaches, marshes, mountains are replaced by housing, hotels, golf- courses etc. 16 June 2010Biodiversity.ppt3

 Hunting -> Elephants for Ivory -> Tigers for pelt -> Bears for medicine  Overfishing  Tuna, Sharks, Other large fish  Whaling/ Dolphin Hunting 16 June 2010Biodiversity.ppt4

Ex. Eliminating coyotes in Southern California- >decrease in bird population Normal Food Web: Bird eggs->raccoon-> coyote No coyote to control the raccoons who will then eat more bird eggs. 16 June 2010Biodiversity.ppt5

Ex. Brown tree snakes were brought into Guam through planes and ships. Snakes have no natural predator in Guam so they reproduced without control. 16 June 2010Biodiversity.ppt6

 Brown Tree Snakes introduced to Guam in the 1950s. In less than 20 years they decimated bird, bat and lizard populations.  On Guam--Caused one power outage every four days 16 June 2010Biodiversity.ppt7

 Pollution-> affects all levels of biodiversity  Global climate change- > changes environmental conditions. Species and population may be lost if they are unable to adapt to new conditions or relocate 16 June 2010Biodiversity.ppt8