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Sustaining Biodiversity: The Species Approach


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Title: Sustaining Biodiversity: The Species Approach

Sustaining Biodiversity The Species Approach
  • Chapter 8

What role do humans play in the extinction of
  • Section 8-1

Extinctions are natural but sometimes they
increase sharply
  • Biological extinction occurs when a species can
    no longer be found anywhere on the earth.
  • The disappearance of species can weaken or break
    some of the connections in the ecosystem.
  • The extinction of many species in a relatively
    short period of geologic time is called a mass

Some human activities are causing extinction
rates to rise
  • Extinction is a natural process but evidence
    indicates that extinction has accelerated as the
    human population has increased, consuming huge
    quantities of resources and creating large and
    growing ecological footprints.
  • Scientists from around the world have estimated
    that the current annual rate of species
    extinction is at least 100 to 1,000 times the
    background rate.
  • The annual extinction rate is projected to rise
    to about 1 per year, mostly because of habitat
    loss and degradation, climate change, and other
    environmentally harmful effects of human
  • At a 1 extinction rate, 25 - 50 of the worlds
    current species could vanish by the end of this

Some human activities are causing extinction
rates to rise
  • A projected extinction rate of 1 a year may be
    on the low side, for several reasons.
  • The rate of species loss and the extent of
    biodiversity losses are likely to increase
    sharply during the next 50100 years due to
    projected growth of the human population.
  • Current and projected extinction rates are much
    higher than the global average in parts of the
    world that are already highly endangered centers
    of biodiversity.
  • Humans are creating a speciation crisis by
    eliminating or degrading many biologically
    diverse environments that are potential sites for
    the emergence of new species.

Some human activities are causing extinction
rates to rise
  • Human activities might help to increase the
    speciation rates for other rapidly reproducing
    opportunist species such as weeds, rodents,
    insects, which could further accelerate the
    extinction of other species.

Endangered and threatened species are ecological
smoke alarms
  • An endangered species has so few individual
    survivors that the species could soon become
    extinct over all or most of its natural range.
  • A threatened species (vulnerable species) still
    has enough remaining individuals to survive in
    the short term, but because of declining numbers,
    it is likely to become endangered in the near
  • Some species have characteristics that make them
    especially vulnerable to ecological and
    biological extinction.

Characteristics that can put certain species in
greater danger of extinction
Blue whale, giant panda, rhinoceros
Low reproductive rate
Blue whale, giant panda, Everglades kite
Specialized niche
Elephant seal, desert pupfish
Narrow distribution
Bengal tiger, bald eagle, grizzly bear
Feeds at high trophic level
Blue whale, whooping crane, sea turtle
Fixed migratory patterns
African violet, some orchids
Snow leopard, tiger, elephant, rhinoceros, rare
plants and birds
Commercially valuable
California condor, grizzly bear, Florida panther
Large territories
Fig. 8-3, p. 154
Percentages of various species threatened with
extinction due to human activities
34 (37 of freshwater species)
Fig. 8-4, p. 155
Why should we care about the rising rate of
species extinction?
  • Section 8-2

Species are a vital part of the earths natural
  • Three major reasons why we should work to prevent
    our activities from causing the extinction of
    other species
  • The worlds species provide natural resources and
    natural services that help to keep us alive and
    support human economies.
  • Various plant species provide food crops,
    fuelwood and lumber, paper, and medicine.
  • Preserving species also provides economic
    benefits through wildlife/eco tourism.

Species are a vital part of the earths natural
  • Analysis of past mass extinctions indicates that
    it will take 510 million years for natural
    speciation to rebuild the biodiversity that we
    are likely to destroy during your lifetime.
  • Many people believe that each wild species has a
    right to exist, regardless its usefulness to us.

How do humans accelerate species extinction?
  • Section 8-3

Loss of habitat is the single greatest threat to
species Remember HIPPCO
  • HIPPCO summarizes the most important causes of
    extinction from human activities
  • Habitat destruction/degradation/fragmentation.
  • Invasive (nonnative) species.
  • Population growth/increasing use of resources.
  • Pollution.
  • Climate change.
  • Overexploitation.

Loss of habitat is the single greatest threat to
species Remember HIPPCO
  • Scientists say that the greatest threat to wild
    species is habitat loss, degradation, and
    fragmentation. The greatest eliminators of
    species are, in order
  • Deforestation in tropical areas.
  • Destruction and degradation of coral reefs and
  • Replacement of biologically diverse grasslands
    with monoculture crops.
  • Pollution of streams, lakes, and oceans.

Reductions in the ranges of four species
Stepped Art
Fig. 8-6, p. 157
Loss of habitat is the single greatest threat to
species Remember HIPPCO
  • Island species, often endemic species found
    nowhere else on earth, are especially vulnerable
    to extinction.
  • Habitat fragmentationby roads, logging,
    agriculture, and urban developmentoccurs when a
    large, intact area of habitat is reduced in area
    and divided into smaller, more scattered and
    isolated patches, or habitat islands.
  • Most national parks and other nature preserves
    are habitat islands.

We have introduced species that can disrupt
  • After habitat loss and degradation, the biggest
    cause of animal and plant extinctions is the
    deliberate or accidental introduction of harmful
    invasive species into ecosystems.
  • Most species introductions are beneficial to us,
    such as food crops, livestock and harvestable
  • Problems arise when introduced species have no
    natural predators, competitors, parasites, or
    pathogens to help control their numbers in their
    new habitat.

Harmful invasive species
Deliberately Introduced Species
Purple loosestrife
European starling
African honeybee (Killer bee)
Salt cedar (Tamarisk)
Purple loosestrife
Water hyacinth
Japanese beetle
African honeybee (Killer Bee)
European wild boar (Feral pig)
Fig. 8-7a, p. 159
Accidentally Introduced Species
Sea lamprey (attached to lake trout)
Argentina fire ant
Brown tree snake
Formosan termite
Zebra mussel
Fig. 8-7b, p. 159
We have introduced species that can disrupt
  • An estimated 7,100 species introduced into the US
    have caused ecological and economic harm.
  • CASE STUDY The Kudzu Vine.
  • A deliberately introduced plant species grows
    rampant in the southeastern US and is known as
    the vine that ate the South.
  • In the 1930s, this vine was imported from Japan
    and planted in the southeastern US in an attempt
    to control soil erosion.

House overtaken by kudzu
Some accidentally introduced species can disrupt
  • Many unwanted nonnative invaders arrive from
    other continents as stowaways on aircrafts,
    ships, wooden packing crates, on cars, or with
  • Terrestrial examples include
  • The aggressive Argentina fire ant which has
    spread over much of the southern US. Fire ants
    can wipe out native ant populations. Fire ant
    mounds can cover fields and yards. When
    disturbed, up to 100,000 ants may attack with
    painful, burning stings. They have killed deer
    fawns, birds, livestock, pets, and at least 80
    people who were allergic to their venom.

Some accidentally introduced species can disrupt
  • Pythons and boa constrictors have ended up in the
    Everglades in Florida after being dumped by their
    owners. Some reach 20 feet long and 200 pounds.
    They are hard to find and kill, and they
    reproduce rapidly. They devour birds, raccoons,
    pet cats and dogs, full-grown deer and
    alligators. Tens of thousands of these snakes now
    live in the Everglades and they may spread to
    other swampy wetlands in the southern half of the

Some accidentally introduced species can disrupt
  • Bioinvaders also affect aquatic systems and are
    blamed for about two-thirds of fish extinctions
    in the US between 1900 and 2009
  • The Great Lakes of North America have been
    invaded by more than 185 alien species. At least
    13 of the recent invading species threaten some
    native species and cause billions of dollars in
  • Fish-killing sea lamprey.
  • Zebra mussel - displaced some species, depleted
    the food supply for others and clogged pipes,
    shutting down water intake pipes for power plants
    and city water supplies, jammed ship rudders, and
    grown in huge masses on boat hulls, piers and
    other solid surfaces.

Zebra mussels attached to a water current meter
in Lake Michigan
Prevention is the best way to reduce threats from
invasive species
  • Scientists suggest several ways to do this
  • Fund a massive research program to identify the
    major characteristics that allow species to
    become successful invaders and the types of
    ecosystems that are vulnerable to invaders.
  • Greatly increase ground surveys and satellite
    observations to detect and monitor species
    invasions and to develop better models for
    predicting how they will spread and what harmful
    effects they might have.

Prevention is the best way to reduce threats from
invasive species
  • Identify major harmful invader species and
    establish international treaties banning their
    transfer from one country to another, as is now
    done for endangered species, while stepping up
    inspection of imported goods to enforce such
  • Require cargo ships to discharge their ballast
    water and replace it with saltwater at sea before
    entering ports, or require them to sterilize such
    water or to pump nitrogen into the water to
    displace dissolved oxygen and kill most invader
  • Educate the public about the environmentally
    harmful effects of releasing exotic plants and
    pets into the environment near where they live.

Ways we can slow or prevent the spread of
invasive species
Population growth, overconsumption, pollution,
and climate change can cause species extinctions
  • Past and projected human population growth and
    excessive and wasteful consumption of resources
    have greatly expanded the human ecological
    footprint, impacting other species.
  • Pollution also threatens some species with
    extinction, as has been shown by the unintended
    effects of certain pesticides.
  • Each year pesticides kill about 20 of the
    honeybee colonies that pollinate almost 33 of
    U.S. food crops, kill more than 67 million birds
    and 614 million fish each year, and threaten
    about 20 of the countrys endangered and
    threatened species.

Population growth, overconsumption, pollution,
and climate change can cause species extinctions
  • The pesticide DDT can be biomagnified about 10
    million times in an estuary food chain, causing
    animals such as the osprey, brown pelican and
    bald eagles to die.
  • Projected climate change could help drive a
    quarter to half of all land animals and plants to
    extinction by the end of this century.

Bioaccumulation and biomagnification
DDT in fish-eating birds (ospreys) 25 ppm
DDT in large fish (needlefish) 2 ppm
DDT in small fish (minnows) 0.5 ppm
DDT in zooplankton 0.04 ppm
DDT in water 0.000003 ppm, or 3 ppt
Fig. 8-11, p. 162
CASE STUDY Where Have All The Honeybees Gone?
  • About one-third of the U.S. food supply comes
    from insect-pollinated plants, and honeybees are
    responsible for 80 of that pollination.
  • A 30 - 40 drop in U.S. honeybee populations has
    been reported since the 1980s, due to
  • Pesticide exposure.
  • Parasitic mites - can wipe out a colony in hours.
  • Invasion by Africanized honeybees.
  • A virus traced to Israel, and a certain fungus.
  • Poor nutrition because of a decrease in the
    natural diversity of flowers and other plants on
    which bees feed.

CASE STUDY Where Have All The Honeybees Gone?
  • In 2010, about 34 of commercial honeybee
    colonies in the U.S. were lost in part to colony
    collapse disorder (CCD), causing adult bees to
    mysteriously disappear.
  • Strategies to help honeybee populations
  • Beekeepers are reducing CCD by practicing
    stringent hygiene, improving the diets of the
    bees, and trying to reduce viral infections.
  • Cut back on use of pesticides, especially at
    midday when honeybees are most likely to be
    searching for nectar.
  • Make our yards and gardens into buffets for honey
    bees by planting native plants that they like.
  • Bees need places to live, so some homeowners are
    purchasing bee houses from their local garden

Illegally killing, capturing, and selling wild
species threatens biodiversity
  • Some protected species are poached for their
    valuable parts or are sold live to collectors.
  • The global illegal trade in wildlife brings in an
    average of at least 600,000 an hour and at least
    66 of all live animals smuggled around the world
    die in transit. Organized crime has moved into
    illegal wildlife smuggling because of the huge
    profits involved.
  • Examples include
  • A highly endangered, live mountain gorilla is
    worth 150,000.

Male mountain gorilla
Illegally killing, capturing, and selling wild
species threatens biodiversity
  • The pelt of a critically endangered giant panda
    can bring 100,000.
  • A poached rhinoceros horn can be worth 25,000
    per pound. Rhinoceros are killed only for their
  • About 25,000 African elephants are killed
    illegally each year for their ivory tusks despite
    an international ban on the sale of poached ivory
    since 1989.
  • A coat made from the fur of the Indian or Bengal
    tiger can sell for as much as 100,000 in Tokyo,
    and the body parts of a single tiger are worth as
    much as 70,000. Without emergency action to
    curtail poaching and preserve their habitat, few
    if any tigers may be left in the wild within 20

Poached white rhinoceros
Illegally killing, capturing, and selling wild
species threatens biodiversity
  • More than 60 bird species, mostly parrots, are
    endangered or threatened because of the wild-bird
  • The pet trade is depleting populations of many
    amphibians, various reptiles, some mammals, and
    many tropical fishes. For each fish caught alive,
    many more die, and the cyanide used to stun
    tropical fish also kills the coral polyps that
    build reefs.
  • Some exotic plants are endangered when they are
    gathered to for houseplants and landscapes.
    Collectors may pay 5,000 for a rare orchid or
    15,000 for a saguaro cactus.

Rising demand for bush meat threatens some
African species
  • Indigenous people in much of West and Central
    Africa have sustainably hunted wildlife for bush
    meat, a source of food, for centuries.
  • In the last two decades, bush meat hunting in
    some areas has skyrocketed as hunters try to
    provide food for rapidly growing populations or
    to make a living by supplying restaurants with
    exotic meats.
  • Bush meat hunting has led to the local extinction
    of many wild animals, driven one species of
    colobus monkey to complete extinction, and been a
    factor in reducing some populations of
    orangutans, chimpanzees, elephants, and

CASE STUDY A Disturbing Message from the Birds
  • Approximately 70 of the worlds known bird
    species are declining in number.
  • The primary culprits appear to be habitat loss
    and fragmentation.

How can we protect wild species from extinction?
  • Section 8-4

International treaties and national laws can help
to protect species
  • The 1975 Convention on International Trade in
    Endangered Species (CITES) is a far-reaching
    treaty signed by 174 countries that bans the
    hunting, capturing, and selling of threatened or
    endangered species.
  • The Convention on Biological Diversity (CBD),
    ratified by 190 countries (but as of 2011, not by
    the United States), legally commits participating
    governments to reversing the global decline of
    biodiversity and to equitably sharing the
    benefits from use of the worlds genetic

The U.S. Endangered Species Act
  • The Endangered Species Act of 1973 (ESA amended
    in 1982, 1985, and 1988) was designed to identify
    and protect endangered species in the United
    States and abroad.
  • Under the ESA, the National Marine Fisheries
    Service (NMFS) is responsible for identifying and
    listing endangered and threatened ocean species,
    while the U.S. Fish and Wildlife Service (USFWS)
    is to identify and list all other endangered and
    threatened species.
  • Any decision to add or remove a species on the
    list must be based on biological factors alone
    without consideration of economic or political

The U.S. Endangered Species Act
  • The ESA forbids federal agencies (except the
    Defense Department) to carry out, fund, or
    authorize projects that would jeopardize an
    endangered or threatened species, or destroy or
    modify its critical habitat.
  • For offenses committed on private lands, fines as
    high as 100,000 and 1 year in prison.
  • Between 1973 and 2011, the number of U.S. species
    on the official endangered and threatened species
    lists increased from 92 to more than 1,320.

The U.S. Endangered Species Act
  • Since 1982, the ESA has been amended to give
    private landowners economic incentives to help
    save endangered species living on their lands.
  • Some believe that the ESA should be weakened or
    repealed, and others believe it should be
    strengthened and modified to focus on protecting
  • The ESA and international agreements have been
    used to identify and protect endangered and
    threatened marine species such as seals, sea
    lions, sea turtles, and whales.

CASE STUDY Protecting Endangered Sea Turtles
  • Six of the worlds seven sea turtle species are
    critically endangered or endangered.
  • Two major threats to sea turtles are loss or
    degradation of beach habitat (where they come
    ashore to lay their eggs and the young hatch),
    and the legal and illegal taking of their eggs.

Endangered leatherback sea turtle tangled in a
fishing net
CASE STUDY Protecting Whales A Success Story .
. . So Far
  • Easier to kill due to their large size and their
    need to come to the surface to breathe.
  • Whalers killed an estimated 1.5 million whales
    between 1925 and 1975, driving 8 of the 11 major
    species to commercial extinction and driving the
    blue whale, the worlds largest animal, to the
    brink of biological extinction.
  • The International Whaling Commission estimates
    some whale species are recovering, but many
    conservationists fear that opening the door to
    any commercial whaling may weaken international
    disapproval and legal sanctions.
  • Despite the ban on whaling, more than 28,000
    whales were hunted and killed between 1986 and
    2010, mostly by the nations of Japan, Norway, and
    Iceland, which have openly defied the ban.

We can establish wildlife refuges and other
protected areas
  • In 1903, President Theodore Roosevelt established
    the first U.S. federal wildlife refuge at Pelican
    Island, Florida, to help protect birds such as
    the brown pelican from extinction.
  • The National Wildlife Refuge System grew to 553
    refuges by 2011.
  • More than three-fourths of the refuges serve as
    wetland sanctuaries that are vital for protecting
    migratory waterfowl.

We can establish wildlife refuges and other
protected areas
  • One-fifth of U.S. endangered and threatened
    species have habitats in the refuge system, and
    some refuges have been set aside for specific
    endangered species, such as Floridas Key deer,
    the brown pelican, and the trumpeter swan.
  • Harmful activities to wildlife such as mining,
    oil drilling, and use of off-road vehicles occur
    in nearly 60 of the nations wildlife refuges.
  • Wildlife refuges receive little funding a third
    of them have no staff, and structures in some
    refuges are in disrepair.

Gene banks, botanical gardens, and wildlife farms
can help to protect species
  • Gene or seed banks preserve genetic information
    and endangered plant species by storing their
    seeds in refrigerated, low-humidity environments.
  • More than 100 seed banks worldwide collectively
    hold about 3 million samples, however
  • Some species cannot be preserved in gene banks.
  • The banks are expensive to operate and can be
    destroyed by fires and other mishaps.
  • A new underground vault on a remote island in the
    Arctic will eventually contain 100 million of the
    worlds seeds and will not be vulnerable to power
    losses, fires, storms, or war.

Gene banks, botanical gardens, and wildlife farms
can help to protect species
  • The worlds 1,600 botanical gardens and arboreta
    contain living plants, representing almost
    one-third of the worlds known plant species but
    only about 3 of the worlds rare and threatened
    plant species.
  • Some endangered or threatened species are raised
    on farms for commercial sale, such as alligator
    farms in Florida and butterfly Papua New Guinea.

Zoos and aquariums can protect some species
  • Zoos, aquariums, game parks, and animal research
    centers are being used to preserve some
    individuals of critically endangered animal
    species, with the long-term goal of reintroducing
    the species into protected wild habitats.
  • Two preserving techniques are
  • 1. Egg pulling, where wild eggs laid by
    critically endangered bird species are collected
    and then hatched in zoos or research centers.

Zoos and aquariums can protect some species
  • 2. Captive breeding, where some or all of the
    wild individuals of a critically endangered
    species are captured for breeding in captivity,
    with the aim of reintroducing the offspring into
    the wild.
  • Limited space and budgets restrict efforts to
    maintain breeding populations of endangered
    animal species that are large enough to avoid
    extinction through accident, disease, or loss of
    genetic diversity due to inbreeding.

The precautionary principle
  • Biodiversity scientists call for us to take
    precautionary action to help prevent premature
    extinctions and loss of biodiversity.
  • The principle advocates that when substantial
    preliminary evidence indicates that an activity
    can harm human health or the environment, we
    should take precautionary measures to prevent or
    reduce such harm even if some of the
    cause-and-effect relationships have not been
    established scientifically.

The precautionary principle
  • Using limited financial and human resources to
    protect biodiversity based on the precautionary
    principle involves dealing with three important
  • How do we allocate limited resources between
    protecting species and protecting their habitats?
  • How do we decide which species should get the
    most attention in our efforts to protect species?
  • How do we determine which areas of land and water
    are the most critical to protect?

Three big ideas
  • We are greatly increasing the extinction of wild
    species by destroying and degrading their
    habitats, introducing harmful invasive species,
    and increasing human population growth,
    pollution, climate change, and overexploitation.
  • We should avoid causing the extinction of wild
    species because of the economic and ecological
    services they provide, and because their
    existence should not depend primarily on their
    usefulness to us.
  • We can work to prevent the extinction of species
    and to protect overall biodiversity by using laws
    and treaties, protecting wildlife sanctuaries,
    and making greater use of the precautionary