Presentation on theme: "BiodiversitySection 2 Objectives Define and give examples of endangered and threatened species. Describe several ways that species are being threatened."— Presentation transcript:
BiodiversitySection 2 Objectives Define and give examples of endangered and threatened species. Describe several ways that species are being threatened with extinction globally. Explain which types of threats are having the largest impact on biodiversity. List areas of the world that have high levels of biodiversity and many threats to species. Compare the amount of biodiversity in the United States to that of the rest of the world.
BiodiversitySection 2 Biodiversity at Risk mass extinction: extinction of many species in a relatively short period of time Earth has experienced several –probably caused by global changes in climate –millions of years for biodiversity to rebound after a mass extinction.
BiodiversitySection 2 Current Extinctions in the midst of another mass extinction rate estimated to have increased by 50x since 1800 @25 % of all species on Earth lost since 1800 difference from past occurrences: humans primary cause
BiodiversitySection 2 Species Prone to Extinction small populations in limited areas especially at risk –those that migrate, –those that need large or special habitats –those that are exploited by humans
BiodiversitySection 2 Endangered species: a species identified to be in danger of extinction throughout all or a significant part of its range, and under protection by regulations or conservation measures Threatened species: a species identified as likely to become endangered in the foreseeable future
BiodiversitySection 2 Large increase in human population considered to be major reason for current mass extinction How Do Humans Cause Extinctions?
BiodiversitySection 2 Cause: use more land to build homes and harvest resources Result: destroy and fragment the habitats of other species –estimated causes @ 75 % of extinctions Habitat Destruction and Fragmentation
BiodiversitySection 2 Example: –Florida Panther requires expansive ranges to obtain prey –habitat destroyed or broken up by roads, canals, and fences –Result- by 2001 <80 wild panthers east of Mississippi river
BiodiversitySection 2 Invasive Exotic Species Cause: species brought to regions where they never lived before Result: –threaten native species that have no natural defenses against them –out compete related native species, replace them Definition Exotic species: species not native to a particular region
BiodiversitySection 2 Cause: Excessive hunting or harvesting for pets, houseplants, wood, food, or herbal medicine Results: species eliminated, rare species endangered Examples: –2 billion passenger pigeons hunted to extinction –thousands of rare species collected Definition Poaching: illegal harvesting of fish, game, other species. Harvesting, Hunting, and Poaching
BiodiversitySection 2 Pollution Cause: pesticides, cleaning agents, drugs, other chemicals get into food webs Results: Short term- chemicals toxic or disrupt nutrient cycles Long term- effects may not be clear bald eagle endangered because of a pesticide DDT, effects not noticed for @20 years
BiodiversitySection 2 Areas of Critical Biodiversity Areas of the world that contain a great diversity of species, have a large portion of endemic species Number of endemic plants used as indicator of overall biodiversity because plants form the basis of ecosystems Definition Endemic species: species that is native to a particular place and found only there
BiodiversitySection 2 Types: Tropical Rain Forests Estimate- contain > ½ all species Only 7 percent of the Earth’s land surface Most of the species never described
BiodiversitySection 2 @60 % of coral reefs threatened by human activities Also affected coastal ecosystems: swamps, marshes, shores, and kelp beds –provide millions of people with food, tourism revenue, coastal protection, and sources of new chemicals –poorly studied, not as well protected by laws as terrestrial areas Coral Reefs and Coastal Ecosystem
BiodiversitySection 2 Islands Often hold a very distinct but limited set of species. Many island species endangered because of invasive exotic species –Example: Hawaiian honeycreeper
BiodiversitySection 2 Biodiversity Hotspots –most threatened areas of high species diversity –high numbers of endemic species –most have lost at least 70 % of their original natural vegetation.
BiodiversitySection 2 Biodiversity in the United States Wide variety of unique ecosystems –Florida Everglades –California coastal region –Hawaii –Midwestern prairies, – temperate rain forest of Pacific Northwest
BiodiversitySection 2 Types of diverse organisms –freshwater fishes, –mussels, snails, crayfish –pine trees and sunflowers
BiodiversitySection 2 Example area: California Floristic Province home to 3,488 native plant species 2,124 are endemic 565 threatened or endangered. Threats: agriculture and housing, dam construction, overuse of water, destructive recreation, and mining