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CH. 10 Biodiversity
“…in the wilderness is the preservation of the world.”
Henry David Thoreau
American Writer and Naturalist
Biodiversity at Risk
• Mass extinctions (extinctions of many species in a short
period of time) have occurred over the course of Earth’s
history
• Most famous is the extinction of the dinosaurs, which
happened over 65 million years ago
• Many worry that we are currently in another period of
mass extinction in Earth’s history
• This extinction is being caused directly by human activity
• Species are disappearing at a rate 1000 times faster
than at any time since the extinction of the dinosaur
A World Rich in Biodiversity
• Biodiversity – the number and variety of species
on Earth
• There are about 1.6 million species known to
science
• Most are insects
• It is estimated that there are actually about 13
million different species on Earth altogether
• Most have not been discovered yet
• Tropical rain forests are the most diverse places
on Earth
How are Humans Causing
Extinctions?
• Population Growth
• The human population is increasing at a rate of
220,000 a day
• As humans take up more and more space and
deplete more resources, we destroy the habitats
of other species
• Unregulated hunting and the introduction of
nonnative species are contributing to extinctions
Habitat Destruction
• Habitat destruction is the leading cause today of
species extinction (75%)
• Ex: Florida panther, in 1994 only 30-50
remained in the wild; whooping crane
• As human populations grow, we need more land
to build homes and harvest resources.
• Most extinctions are occurring in tropical rain
forests
Hunting
• Unregulated hunting can lead to species extinction, too
• Ex: early 1900’s, 2 billion American passenger pigeons
were legally hunted to extinction; American buffalo was
nearly hunted to extinction in the 1800’s (60 million in the
1800’s, 1906 only 300 remained)
• Wildlife laws in the U.S. ensure only a certain number of
game animals are killed each year; laws were
established to protect certain animals and invoke heavy
fines and possible jail time for poachers
• In developing countries, poaching (illegal hunting), as a
means for survival, still exists and threatens many
species ex: African elephants
Exotic species
• Exotic species are species that are not native to
a particular region, brought into an area where
they never lived before, and have no natural
defenses against them
• Ex: Melaleuca tree in South Florida and the
Kudzu plant which is invading the South and
moving North
The Value of Biodiversity
• Extinction is a natural process – species
appear, flourish for a time and then
become extinct; 99% of all the species that
have ever lived are now extinct
• Protecting species on the verge of
extinction is difficult and expensive
Saving Species Preserves
Ecosystems
• Saving species preserves ecosystems
• The balance of species keeps the flow of energy regulated and
cycles nutrients properly
• It’s impossible to accurately predict how the loss of certain species
will affect an ecosystem…where is the breaking point?
• Keystone species – a species who is so important to an ecosystem
that its loss may cause a total collapse; ex: sea otter
Practical Uses of Species
• Forty (40%) percent of all prescription drugs
originate from living species
• Medicinal plants have been made to treat
childhood leukemia, cancer, Parkinson’s
disease
• Loss of biodiversity may mean a loss in
developing future medicines, finding potential
food sources, and discovering naturally found
plants resistant to pests and fungus.
Ethical and Aesthetic Reasons
• Many believe that humans have a
responsibility to tend to the Earth’s
organisms
• People believe that loss of a species
means a loss in beauty and wonderment
• Time spent among other living things
renews our sense of connection with life
and our appreciation of the world in which
we live
10.2 Public Policy
• Biodiversity and public policy
• The Endangered Species Act – this law is
designed to protect plant and animal
species in danger of extinction
The Endangered Species Act
• The U.S. fish and wildlife service must compile a list of all
endangered and threatened species
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- an endangered species is one whose #’s have grown so low that it is likely
to become extinct in the future
- a threatened species is one that is likely to become endangered if it is not
protected
• Endangered and threatened animal species my not be caught or
killed; plants on federal land may not be uprooted; no part of any
endangered or threatened plant or animal my be sold or traded
• The Federal government may not carry out any project that
jeopardizes endangered species
• The U.S. fish and wildlife service must prepare a species recovery
plan for each endangered and threatened species
•
- the most effective way to save a species is through a protection of their
habitat
Developers vs. Environmentalists
• Plans involving restriction of land use are
sometimes controversial
• From the developers viewpoint:
• - may disrupt plans for development of an area
• - may cost jobs for community members
• - may cost investors a lot of money
• From the environmentalists viewpoint:
• - no money making venture is worth the extinction of a species
• These standoff’s usually end up in court and
then eventually in some sort of compromise
Worldwide Efforts to Prevent Extinctions
• Several international organizations work to
protect species:
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The World Wildlife Fund
The Nature Conservancy
Conservation International
Friends of the Earth
Greenpeace International
International Union for the Conservation of Nature and Natural
Resources
• The Convention on International Trade in Endangered Species
(CITES)
• The Biodiversity Treaty
Prevention of Poaching
• CITES, in 1989, proposed a total
worldwide ban on all sales, imports and
exports of ivory; hopes to put a stop to the
slaughter of African elephants for their
ivory tusks
• Sale of ivory was completely banned in
1989; consequently, the poaching of
elephants declined dramatically
The Biodiversity Treaty
• Earth Summit, in 1992, which took place in
Rio de Janeiro, Brazil (100 world leaders
and 30,000 participants) met to tackle
environmental issues; result was the
Biodiversity Treaty
• Former president Bush did not sign,
stating it was too vague; following year,
former president Clinton signed it
10.3 The Future of Biodiversity
• 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.
Saving Individual Species
• Legislation such as the Endangered
Species Act and anti-poaching laws are
attempts to save individual species.
• Additional ways to save species are
captive-breeding programs, botanical
gardens and germ-plasm banks.
Captive-Breeding Programs
• Used by zoos and wild animal parks
• Animals are protected and allowed to mate
in captivity
• If numbers climb high enough, some are
released back into the wild
• Ex: California condor
Botanical Gardens
• Places where rare and exotic plants are
grown in order to protect biodiversity
• Botanical Gardens house nearly 90,000
different species of plants worldwide
• That still is not enough to protect most of
the world’s endangered and threatened
plants
Germ-Plasm Banks
• Stores endangered plants and animal
genetic information in the form of plant
seeds or the frozen sperm and eggs of
endangered animals
• This genetic information may be used if
the plant or animal becomes critically
endangered
• This genetic information can last for many,
many years
The Ecosystem Approach
• Protects entire ecosystems instead of individual
organisms
• Two reasons for the ecosystem approach:
• - more species are in danger of extinction than can possibly be
placed on official lists; so by protecting ecosystems we can save
most of the species in an ecosystem instead of just one; we may
also be protecting species that we are not even aware of
• - preserving ecosystems protects the health of the biosphere
• Many believe special consideration should be
given to ecological hot spots
• - areas with especially high biodiversity
What About Human Needs?
• We must find ways to meet the human
needs and manage living resources at the
same time
• In poorer nations of the world, the conflict
between human needs and biodiversity
may even be a matter of life or death
• Preserving these resources will most likely
be the greatest challenge of the 21st
century.