1. SC.912.L.17.8

2. Earth's Biodiversity

3. Earth’s biodiversity Biodiversity – the diversity of life on Earth – variety at all levels of biological organization Components of biodiversity: Genetic diversity – genetic variation within populations or species Species diversity – numbers of species within an area Diversity among higher taxa – variation between genera, families, orders, etc. Ecosystem diversity – variation among ecosystems, communities, landscapes

4. Why is biodiversity important? Economic value – resources, including food – medicines and other helpful chemicals – genes for better crops – “opportunity cost” Utilitarian value – prevent erosion – purify water – recycle CO2 – regulate climate – recycle nutrients through decomposition – collectively, “ecosystem services” Psychological value – direct or indirect enjoyment of nature Intrinsic value – independent of humans

5. What is the “biodiversity crisis”? Humans are causing extinctions at a tremendous rate. ~100 times faster than expected without human activity parallels or exceeds previous mass extinction events Why is the loss of biodiversity a crisis? economic value of biodiversity lost or threatened “ecological services” lost or threatened ecosystems more vulnerable to further degradation

6. What are the biggest threats to biodiversity? habitat destruction and fragmentation pollution introduced species overexploitation

7. Habitat Destruction & Fragmentation When land is developed, natural habitats may be destroyed Habitat fragmentation: development splits an ecosystem into pieces Result is that pieces of the habitat become islands; allowing fewer species to live there The smaller the population=more vulnerable to further disturbance or climate change

8. Overexploitation Throughout history, humans have pushed some animals into extinction by hunting them for food or other products Hunting still threatens rare animals in parts of Africa, South America, and Southeast Asia For meat, fur, or hides Some believe parts have medicinal properties

9. Pollution DDT Sewage and garbage Runoff All of these get into ground water supplies and can be consumed by plants, and then animals

10. Introduced species Invasive species: non-native plants and animals introduced to an area, reproduce rapidly, and out- compete the local organism