chapter 10 biodiversity

… In wilderness is the Preservation of the world.

A mass extinction is the Extinction of many species duringA relatively short period of time.

The earth has experienced 5 mass extinctions, each

Probably caused by some change In climate.

Many scientists believe that weAre living in another massExtinction that would leave25% of all species extinct

By the year 2100.

If this is true, it will be the First caused by an organism…

Humans!

The term biodiversity refersTo the number of variety

Of species on Earth.

Of the approximately 1.6 millionSpecies on earth, most

Are insects.

The human population is Increasing by about 220 000

People each day!!

Because the human populationIs growing so rapidly, we are

Causing other species to Become extinct at an

Accelerated rate.

As human populations grow, we Use more land to build homes

And harvest resources.

It is estimated that habitat lossCauses almost 75% of the Extinctions now occurring.

Most extinctions are Occurring in tropical rain forests

When land is cleared for Farming or cattle grazing.

Unregulated hunting can alsoLead to species extinction.

In the early 1900’s the American Passenger pigeon was

Legally hunted to extinction.

Similarly, the American buffaloWas nearly hunted to extinction

In the 1800’s.

In many countries, Poaching (illegal hunting), can threaten

Animals with extinction.

This happened to elephantsIn 1979 when poachers were Hunting the beasts to meet

the demand for ivory tusks.

An exotic species is a species thatIs not native to a particular

Region.

Even such familiar organismsSuch as cats and rats, are

Considered to be exotic when They are brought to regions

Where they have never Lived before.

Species, along with abiotic Factors, are what make

Up ecosystems.

Each species plays a role In its ecosystem.

Some species are so importantTo the functioning of an Ecosystem that they are Called keystone species.

When sea otters were huntedTo near extinction on thePacific coast, their entire

Ecosystem was disrupted.

There are also practical uses For certain species.

About 40% of all prescription Drugs were derived from

Living things.

So scientists are concernedThat the loss of biodiversity,Especially in the Rain forests,

Will limit the development Of future medicines.

The united states congress Passed the Endangered SpeciesAct in 1973 and has amended

It several times.

This law is designed to Protect plant and animal

Species in danger of extinction.

There are 4 main provisions…

Under the 1st main provision, The US Fish and Wildlife

Service must compile a list of All endangered and threatened

Species.

To be considered endangered,A species numbers must haveFallen so low that it is likely

To become extinct in the Near future.

Threatened species are species That are likely to become

Endangered if they are Not protected.

The second main provision statesThat endangered or threatened

Animals may not be caught.

None of the species, nor any Of their parts, can be sold

Or traded.

According to the 3rd provision, The federal government

May not carry out any projectThat jeopardizes an Endangered species.

And the 4th provision says that A recovery plan for each

Endangered or threatenedSpecies.

There are also international Organizations to help species.

The world wildlife fund worksTo protect biodiversity,

Especially in rain forests.

The Nature Conservancy Currently manages over 1500 nature sanctuaries.

Greenpeace International Stages dramatic protest to stop

The killing of animals.

The international union for the Conservation of nature and Natural resources is in the

Forefront of efforts to protectSpecies and habitats.

It is possible to slow the loss of Species, but to do so we must Develop new approaches to

Conservation and a sensitivity To human needs around the globe.

Additional ways to preserveIndividual species include

Captive-breeding programs, Botanical gardens, and

Germ-plasm banks.

Germ-plasm banks store germ Plasm for future use in case

Species become criticallyEndangered.

Germ-plasm is the genetic materialContained within the reproductive

Cells of organisms.

Zoos and wild-animal parksCan increase the population

Of an endangered or Threatened species by

Establishing captive-breedingPrograms.

Such programs involve breedingAnimals under carefully

Managed circumstances.

Botanical gardens worldwideHouse 90 000 species of plants.

Even so, the gardens don’t haveThe space of the funds to

Preserve most of the worldsRare and threatened plants.

Recently, manyConservationists have begunTo concentrate on protecting

Entire ecosystems.

This helps to save many organismsThat can’t be placed on listsAnd these ecosystems can

Help save the entire planet.