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Biodiversity Section #2: Biodiversity at Risk. Extinctions changes in Earth’s climate & ecosystems have caused the extinction of about ½ the species on.

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Presentation on theme: "Biodiversity Section #2: Biodiversity at Risk. Extinctions changes in Earth’s climate & ecosystems have caused the extinction of about ½ the species on."— Presentation transcript:

1 Biodiversity Section #2: Biodiversity at Risk

2 Extinctions changes in Earth’s climate & ecosystems have caused the extinction of about ½ the species on Earth

3 Mass Extinctions the loss of many species in a relatively short period of time it takes millions of years for biodiversity to rebound after a mass extinction

4 Mass Extinction Events Over Geologic Time

5 Current Extinctions scientists warn that we’re in the midst of another mass extinction between 1800 & 2100, up to 25% of all species on Earth may have become extinct primary cause = humans (this is different from the past)

6 Threatened & Extinct Species Worldwide

7 Species Prone to Extinctions species with small populations species with limited habitats species that migrate species that need special habitats species that need lots of space species that are exploited by humans

8 Endangered vs. Threatened endangered species = a species that is like to become extinct if protective measures are not taken immediately threatened species = a species that has a declining population & is likely to become endangered if not protected

9 Endangered Florida Panthers

10 How Do Humans Cause Extinctions? human population growth that has lead to... –habitat destruction & fragmentation –pollution –introduction of nonnative species –over-harvesting of species

11 Habitat Loss we use more land to build homes & for harvesting resources this destroys & fragments the habitats for other species 75% of extinctions occur because of habitat loss

12 Invasive Exotic Species a species that is not native to a particular region they are brought to an area where they never lived before exotic species can threaten native species that have no natural defenses

13 Invasive Exotic Species Fire Ant Mounds

14 Harvesting, Hunting, Poaching many countries now have laws to regulate hunting, fishing, harvesting, & wildlife trade to cut down on excessive loss of species not all threatened species are legally protected, especially in poorer countries where they might be a source of food, medicine, or income

15 Poaching

16 Pollution pesticides, cleaning agents, drugs, & other chemicals used by humans are making their way into food webs around the globe we often don’t know the long- term effects until its too late

17 Pollution bald eagles became endangered from the pesticide DDT (now illegal to use in the U.S. still manufactured here and sold around the world) the DDT caused a thinning in the eagle’s eggshells & the babies did not survive

18 Endemic Species species that are native to and found only with a limited area scientists often use the numbers of endemic species of plants as an indicator of overall biodiversity

19 Areas of Critical Biodiversity tropical rain forests coral reefs coastal ecosystems islands

20 Tropical Rain Forests only cover a small % of the Earth’s land surface (<7%) biologists estimate that over ½ of the world’s species live in these forests most of these species have not been described unknown #s of species are disappearing as tropical rain forests are cleared for farming cattle grazing

21 Tropical Rain Forests the Amazon has had an influx of visitors, not only tourists, but also scientists who are searching for new species to create new products, especially drugs the Brazilian government has now claimed the right to tax or patent any genetic material harvested with in its borders

22 Coral Reefs only occupy a small fraction of the ocean, but contain the majority of biodiversity reefs provide millions of people with food, tourism revenue, coastal protection, sources of new chemicals some have placed a value of $375 billion per year

23 Coastal Ecosystems threatened by human activities, particularly development along waterways, filling in swamps and marshes too much pollution is becoming a bigger problem, these ecosystems act as a buffer zone but still have limitations

24 Islands often hold very distinct, but limited numbers of species most species have migrated from the mainland and then evolved into new species introduction of invasive exotic species can destroy the island’s species

25 Biodiversity Hotspots the most threatened areas of high species diversity around the world have high numbers of endemic species that are threatened by human activities most have already lost 70% of their original vegetation typical hotspots are tropical rainforests, coastal areas, & islands

26 Hotspots

27 Biodiversity in the U.S. areas = Florida Everglades, California coastal regions, Hawaii, Midwestern prairies, Pacific NW forests species = freshwater fishes, mussels, snails, crayfish, pine trees, sunflowers, birds

28 Endemic Species to the U.S.

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