Biodiversity
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Biodiversity. Section #2: Biodiversity at Risk. changes in Earth’s climate & ecosystems have caused the extinction of about ½ the species on Earth. Extinctions. the loss of many species in a relatively short period of time

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Biodiversity

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Biodiversity

Biodiversity

Section #2:

Biodiversity at Risk


Extinctions

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

Extinctions


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

Mass Extinctions


Mass extinction events over geologic time

Mass Extinction Events Over Geologic Time


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)

Current Extinctions


Threatened extinct species worldwide

Threatened & Extinct Species Worldwide


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

Species Prone to Extinctions


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

Endangered vs. Threatened


Endangered florida panthers

Endangered Florida Panthers


How do humans cause extinctions

human population growth that has lead to . . .

habitat destruction & fragmentation

pollution

introduction of nonnative species

over-harvesting of species

How Do Humans Cause Extinctions?


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

Habitat Loss


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

Invasive Exotic Species


Invasive exotic species fire ant mounds

Invasive Exotic SpeciesFire Ant Mounds


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

Harvesting, Hunting, Poaching


Poaching

Poaching


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

Pollution


Pollution1

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

Pollution


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

Endemic Species


Areas of critical biodiversity

tropical rain forests

coral reefs

coastal ecosystems

islands

Areas of Critical Biodiversity


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

Tropical Rain Forests


Tropical rain forests1

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

Tropical Rain Forests


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

Coral Reefs


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

Coastal Ecosystems


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

Islands


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

Biodiversity Hotspots


Hotspots

Hotspots


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

Biodiversity in the U.S.


Endemic species to the u s

Endemic Species to the U.S.


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