CHAPTER 8
SUSTAINING BIODIVERSITY: SAVING SPECIES AND
ECOSYSTEMS SERVICES
Outline
8-1 What role do humans play in the loss of species and ecosystem services?
A. Extinctions are natural but sometimes they increase sharply.
2. The disappearance of species can weaken or break some of the connections in the ecosystem.
3. The extinction of many species in a relatively short period of geologic time is called a mass
extinction.
B. Some human activities are causing extinction rates to rise
1. Extinction is a natural process but evidence indicates that extinction has accelerated as the
2. 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.
3. The annual extinction rate is projected to rise to about 1% per year, mostly because of habitat
4. At a 1% extinction rate, at least 25% and as many as 50% of the world’s current animal and
plant species could vanish by the end of this century.
5. A projected extinction rate of 1% a year may be on the low side, for several reasons.
a. The rate of species loss and the extent of biodiversity losses are likely to increase
6. 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.
C. SCIENCE FOCUS: Estimating extinction rates.
1. Difficulties in estimating extinction rates include:
a. Because the extinction of a species typically takes a very long time, it is not easy to
2. Methods include:
a. Studying records that document the rates at which mammals and birds have become
extinct since humans began their rapidly increasing domination of the planet about
Instructor’s Manual for Environmental Science, 15th edition
D. Endangered and threatened species are ecological smoke alarms.
2. A threatened species (vulnerable species) still has enough remaining individuals to survive in
3. Some species have characteristics that make them especially vulnerable to ecological and
biological extinction.
8-2 Why should we try to sustain wild species and the ecosystem services they provide?
A. Species are a vital part of the earth’s natural capital.
1. Three major reasons why we should work to prevent our activities from causing the extinction
of other species:
a. The world’s species provide natural resources and natural services that help to keep us
alive and support human economies.
i. Various plant species provide food crops, fuel, wood and lumber, paper, and
medicine.
8-3 How do humans accelerate species extinction and degradation of ecosystem services?
A. Loss of habitat is the single greatest threat to species: remember HIPPCO.
1. The acronym HIPPCO summarizes the most important direct causes of extinction resulting
from human activities:
• Habitat destruction, degradation, and fragmentation.
• Invasive (nonnative) species.
2. 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 wetlands.
4. Habitat fragmentation—by roads, logging, agriculture, and urban development—occurs when
5. Most national parks and other nature preserves are habitat islands.
B. We have introduced species that can disrupt ecosystems
2. Most species introductions are beneficial to us, such as food crops, livestock and harvestable
trees.
4. An estimated 7,100 species introduced into the United States have caused ecological and
economic harm.
5. CASE STUDY: The Kudzu Vine.
Chapter 8: Sustaining Biodiversity: The Species Approach
C. Some accidentally introduced species can disrupt ecosystems
1. Many unwanted nonnative invaders arrive from other continents as stowaways on aircraft, in
2. Terrestrial examples include:
• The aggressive Argentina fire ant which has spread over much of the southern United
States. 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.
3. Bioinvaders also affect aquatic systems and are blamed for about two-thirds of fish
extinctions in the United States 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 damages.
D. Prevention is the best way to reduce threats from invasive species.
1. 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.
E. Population growth, overconsumption, pollution, and climate change can cause species extinctions.
1. Past and projected human population growth and excessive and wasteful consumption of
resources have greatly expanded the human ecological footprint, impacting other species.
2. Pollution also threatens some species with extinction, as has been shown by the unintended
effects of certain pesticides.
3. Projected climate change could help drive a quarter to half of all land animals and plants to
extinction by the end of this century.
4. 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,
with the following possible causes:
i. Pesticide exposure (the wax in beehives absorbs these and other airborne
toxins).
ii. Attacks by parasitic mites that can wipe out a colony in hours.
iii. Invasion by Africanized honeybees.
F. Illegally killing, capturing, and selling wild species threatens biodiversity.
1. Some protected species are illegally killed (poached) for their valuable parts or are sold live to
collectors.
2. The global illegal trade in wildlife brings in an average of at least $600,000 an hour and at
3. Examples include:
• A highly endangered, live mountain gorilla is worth $150,000.
• 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 for
no other reason than to harvest their horns.
• 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
landscapes. Collectors may pay $5,000 for a rare orchid or $15,000 for a saguaro cactus.
4. INDIVIDUALS MATTER: A Scientist Who Confronted Poachers.
• In Thailand, biologist Pilai Poonswad decided to do something about poachers taking
Chapter 8: Sustaining Biodiversity: The Species Approach
them why the birds are worth more alive than dead, so they could make more money
from them being alive.
G. Rising demand for bush meat threatens some African species.
1. Indigenous people in much of West and Central Africa have sustainably hunted wildlife for
bush meat, a source of food, for centuries.
2. In the last two decades, bush meat hunting in some areas has skyrocketed as hunters try to
3. 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 hippopotamuses.
H. CASE STUDY: A Disturbing Message from the Birds.
1. Approximately 70% of the world’s known bird species are declining in number.
2. The primary culprits appear to be habitat loss and fragmentation.
I. SCIENCE FOCUS: Vultures, Wild Dogs, and Rabies: Some Unexpected Scientific Connections.
2. Populations of three species of carcass-eating vulture fell by more than 97% due to their
8-4 How can we sustain wild species and the ecosystem they provide?
A. International treaties and national laws can help to protect species.
1. The 1975 Convention on International Trade in Endangered Species (CITES) is a far-reaching
2. 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
B. The U.S. Endangered Species Act.
1. 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.
2. Under the ESA, the National Marine Fisheries Service (NMFS) is responsible for identifying
4. The ESA forbids federal agencies (except the Defense Department) to carry out, fund, or
5. For offenses committed on private lands, fines as high as $100,000 and one year in prison can
be imposed, although this provision is rarely used.
7. Since 1982, the ESA has been amended to give private landowners economic incentives to
help save endangered species living on their lands.
9. 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.
C. CASE STUDY: Protecting Endangered Sea Turtles.
1. Six of the world’s seven sea turtle species are critically endangered or endangered.
D. CASE STUDY: Protecting Whales: A Success Story . . . So Far.
1. Whales are fairly easy to kill because of their large size and their need to come to the surface
to breathe.
a. 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 world’s
largest animal, to the brink of biological extinction.
defied the ban.
E. We can establish wildlife refuges and other protected areas.
2. The National Wildlife Refuge System grew to 553 refuges by 2011.
4. One-fifth of U.S. endangered and threatened species have habitats in the refuge system, and
5. Activities considered harmful to wildlife such as mining, oil drilling, and use of off-road
vehicles occur in nearly 60% of the nation’s wildlife refuges.
6. For years, the country’s wildlife refuges have received so little funding that a third of them
have no staff, and structures in some refuges are in disrepair.
F. Gene banks, botanical gardens, and wildlife farms can help to protect species.
2. More than 100 seed banks around the world collectively hold about 3 million samples, but
problems include:
3. The world’s 1,600 botanical gardens and arboreta contain living plants, representing almost
4. Some endangered or threatened species are raised on farms for commercial sale, such as
alligator farms in Florida and butterfly Papua New Guinea.
G. Zoos and aquariums can protect some species.
1. Zoos, aquariums, game parks, and animal research centers are being used to preserve some
2. Two techniques for preserving endangered terrestrial species are:
a. Egg pulling, where wild eggs laid by critically endangered bird species are collected and
3. Limited space and budgets restrict efforts to maintain breeding populations of endangered
H. The precautionary principle.
1. Biodiversity scientists call for us to take precautionary action to help prevent premature
extinctions and loss of biodiversity.
Chapter 8: Sustaining Biodiversity: The Species Approach
2. Using limited financial and human resources to protect biodiversity based on the
precautionary principle involves dealing with three important questions:
a. How do we allocate limited resources between protecting species and protecting their
habitats?
3. This chapter’s three big ideas:
a. 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.
b. We should avoid causing the extinction of wild species because of the economic and
Objectives
8-1 What role do humans play in the loss of species and ecosystem services?
CONCEPT 8-1 Species are becoming extinct 100 to 1,000 times faster than they were before the human
population grew exponentially, and by the end of this century, the extinction rate is expected to be 10,000 times
higher.
1. Distinguish between background (natural) rate of extinction and mass extinction. Evaluate if an
extinction crisis currently exists. Describe three methods for estimating extinction rate.
8-2 Why should we try to sustain wild species and the ecosystem services they provide?
CONCEPT 8-2 We should avoid speeding up the extinction of wild species because of the ecosystem and
economic services they provide, because it can take millions of years for nature to recover from large-scale
extinctions, and because wild species have a right to exist regardless of their usefulness to us.
1. Describe the economic, medical, aesthetic, ecological, and ethical significance of wild species.
8-3 How do humans accelerate species extinction and degradation of ecosystem services?
CONCEPT 8-3 The greatest threats to species and ecosystem services are (in order) loss or degradation of its
habitat, harmful invasive species, human population growth, pollution, climate change, and overexploitation.
1. Describe how species become extinct. List and describe eight ways that humans accelerate the
extinction rate. List the terms represented by the acronym HIPPCO.
8-4 How can we sustain wild species and the ecosystem services they provide?
CONCEPT 8-4 We can reduce species extinction and sustain ecosystem services by establishing and enforcing
national environmental laws and international treaties and by and protecting wildlife sanctuaries.
1. List and briefly describe three approaches to protecting wild species from extinction. State one
advantage particular to the ecosystem approach.
4. Describe three ways that plant species can be preserved. Define gene (seed) bank and describe two
problems with this approach.
6. List three ways individuals can help maintain wild species and preserve biodiversity.
Key Terms
background extinction rate
biological extinction
HIPPCO
mass extinction
social science principles of
sustainability
Teaching Tips
Because students may be unaware of their influence on species survival, begin by asking how they affect
species during their everyday life. Use the case study to introduce the notion that once species are gone and
ecosystems have been altered, it is too late. Therefore, we must be aware of our impacts and read the
ecological signals (e.g., indicator species) before irreversible damage is done.
• Ask the students how humans can slow or eliminate species loss.
• Then discuss the strategies that exist to do so, which are most practical, and the advantages and
disadvantages of each.
• The notion that humans’ actions impact species and their survival may be new to students. Spend
Discussion Topics
1. Describe the scientific methods for estimating wildlife populations and specify the successional stage
of ecosystems. How is this process useful?
2. What role do Ducks Unlimited, the National Wildlife Federation, the Audubon Society, Greenpeace,
Sea Shepherds and Earth First! play in preserving biodiversity?
3. How does America’s National Wildlife Refuge System work to preserve biodiversity?
7. How can gene banks, zoos and captive breeding programs, habitat management, and artificial reef-
building materials and methods help protect wildlife?
8. Are extremist tactics by Greenpeace, Sea Shepherds and Earth First! necessary or justifiable?
Activities and Projects
1. Are there zoos, aquariums, botanical gardens, or arboreta in your area that are operating programs
designed to increase the populations of endangered species? If so, invite a spokesperson to explain one
2. Ask your students to bring to class and share paintings, sketches, poetry, songs, and other artistic
creations depicting the beauty and wonders of wildlife.
4. Should animals be used for medical research? As sources of organs for surgical implants in humans?
Attitudes and Value Assessment
1. Do you believe that humans have a duty to subdue wild nature to provide food, shelter, and other
resources for people and to provide jobs and income through increased economic growth?
2. Do you believe that every living species has a right to exist, or at least struggle to exist, simply because
it exists?
Laboratory Skills
Wells, Edward. Lab Manual for Environmental Science. 2009. Lab #4: Biomagnification Through a Food
Chain.
News Videos
Are We Facing an Extinction Crisis?, The Brooks/Cole Environmental Science Video Library 2009,
©2011, DVD ISBN-13: 978-0-538-73355-7
Instructor’s Manual for Environmental Science, 15th edition
How Exotic Species Are Devastating Hawaii’s Native Species, The Brooks/Cole Environmental Science
Video Library 2009, ©2011, DVD ISBN-13: 978-0-538-73355-7
Cane Toads: An Unnatural History (Documentary, 1988)
An irreverent documentary detailing the spread of Hawaiian sugar-cane toads through Australia in a
botched effort to introduce them as counter-pests.
http://www.amazon.com/Cane-Toads-Unnatural-Tip-Byrne/dp/B00005JG6X/ref=cm_cr_pr_product_top
Frontline: World, Mexico: The Business of Saving Trees (Documentary, 2008, Online)
A look at how the carbon credit system has been use to create jobs in Mexico.
http://www.pbs.org/frontlineworld/rough/2008/03/mexico_the_busi.html
Web Resources
Bridge
http://www.vims.edu/bridge/
A variety of resources for teachers that may be adaptable to the college level.
Centers for Ocean Sciences Education Excellence
Chapter 8: Sustaining Biodiversity: The Species Approach
Hope Spots
Marine scientist and conservationist Sylvia Earle has coined the term Hope Spots for special places that are
critical to the health of the ocean.
. Digital Integration
Correlation to Global Environment Watch
Animal Welfare Habitat Loss Protected Areas
Biodiversity Impact of Tourism and Recreation Seed Banks
Coral Reefs IUCN U.S. EPA
Correlation to Virtual Field Trips
Invasive Exotic Species
Correlation to Explore More
Aquatic Ecosystems Environmental Law Saving Species
Biodiversity Extinction
Environmental History Indigenous Cultures
Suggested Answers to End of Chapter Questions
Answers will vary but these represent phrases from this chapter. The following are examples of the material
that should be contained in possible student answers to the end of chapter questions. They represent only a
summary overview and serve to highlight the core concepts that are addressed in the text. It should be
anticipated that the students will provide more in-depth and detailed responses to the questions depending
on an individual instructor’s stated expectations.
Review
1. What economic and ecological services do honeybees provide? How are human activities contributing
to the decline of many populations of European honeybees? What is colony collapse disorder (CCD)?
Instructor’s Manual for Environmental Science, 15th edition
ii. Attacks by parasitic mites that can wipe out a colony in hours.
Section 8-1
2. What is the key concept for this section? Define and distinguish between biological extinction and
mass extinction. What is the background extinction rate, and how do estimated current and projected
extinction rates compare with it? What percentage of the earth’s land and what percentage of the
earth’s oceans have been disturbed by human activities? Explain how scientists estimate
extinction rates and describe the challenges they face in doing so. Give three reasons why many
extinction experts believe that projected extinction rates are probably on the low side. What percentage
of the world’s species are likely to go extinct, largely as a result of human activities, during this
century? Distinguish between endangered species and threatened species and give an example of each.
List four characteristics that make some species especially vulnerable to extinction.
• CONCEPT 8-1 Species are becoming extinct 100 to 1,000 times faster than they were before
modern humans evolved, and by the end of this century, the extinction rate is expected to be
10,000 times higher.
• Biological extinction is when a species can no longer be found anywhere on the earth.
• Mass extinction is the extinction of many species in a relatively short period of geologic time.
• Extinction of one species may lead to extinction of another because of their dependence on each
other or the same variable(s) leading to the extinction.
• Methods for estimating extinction rates include:
o Studying records that document the rates at which mammals and birds have become
extinct since humans began their rapidly increasing domination of the planet about
10,000 years ago, and comparing this information with fossil records of extinctions that
occurred before the development of agriculture/
• Humans may be causing a new mass extinction as our population grows and as we consume more
resources, disturb more land and aquatic systems, and cause changes to the earth’s climate.
• At least 25% and as many as 50% of the world’s current animal and plant species could vanish by
the end of this century.
• An endangered species has so few individual survivors that the species could soon become extinct
over all or most of its natural range (the area in which it is normally found). Examples include the
Section 8-2
3. What is the key concept for this section? What are three reasons for trying to avoid causing the
extinction of wild species? Describe two economic and two ecological benefits of species diversity.
Chapter 8: Sustaining Biodiversity: The Species Approach
CONCEPT 8-2 We should avoid speeding up the extinction of wild species because of the economic
and ecological services they provide, and because wild species have a right to exist regardless of their
usefulness to us.
• Three reasons why we should work to prevent our activities from causing the extinction of other
species are:
o The world’s species provide natural resources and natural services that help to keep us
alive and support human economies.
o Analysis of past mass extinctions indicates that it will take 5–10 million years for natural
speciation to rebuild the biodiversity that we are likely to destroy during your lifetime.
Section 8-3
4. What is the key concept for this section? What is HIPPCO? What is the greatest threat to wild species?
What is habitat fragmentation? Describe the major effects of habitat loss and fragmentation. Why are
island species especially vulnerable to extinction? What are habitat islands?
• CONCEPT 8-3 The greatest threats to any species are (in order) loss or degradation of habitat,
harmful invasive species, human population growth, pollution, climate change, and
overexploitation.
• HIPPCO: Habitat destruction, degradation, and fragmentation; Invasive (nonnative) species;
population and resource-use growth (too many people consuming too many resources); pollution;
climate change; and overexploitation.
• The greatest threats to any species are (in order) loss or degradation of its habitat, harmful invasive
species, human population growth, pollution, climate change, and overexploitation. Deforestation
in tropical areas is the greatest eliminator of species
5. Give two examples of the harmful effects of nonnative species that have been introduced deliberately
and two examples of the same for accidentally introduced species. Explain why prevention is the best
way to reduce threats from invasive species and list four proposed ways to implement this strategy.
• Benefits of introducing non-native species include use as food crops and livestock. Non-native tree
species are grown in about 85% of the world’s tree plantations. Some introduced species have
a source of fiber for making paper and possible medications.
• Once a harmful nonnative species becomes established in an ecosystem, its removal is almost
impossible.
• Ways to prevent the establishment of nonnative species include:
o Fund a massive research program to identify the key characteristics that enable some species
to become successful invaders; the types of ecosystems that are vulnerable to invaders; and
the natural predators, parasites, bacteria, and viruses that might be used to control
populations of established invaders.
6. Summarize the roles of population growth, overconsumption, pollution, and climate change in the
extinction of wild species. Explain how concentrations of pesticides such as DDT can accumulate to
high levels in food webs. List possible causes of the decline of European honeybee populations in the
United States. Give three examples of species that are threatened by poaching. Why are wild tigers
likely to disappear within a few decades? What is the connection between infectious diseases in
humans and the pet trade? Describe the threat to some forms of wildlife from the increased hunting for
bush meat
• Fat-soluble chemicals, such as DDT, can accumulate in the fatty tissues of animals (see Figure 8-
11). In a food chain or web, the accumulated DDT is biologically magnified in the bodies of
animals at each higher trophic level.
• See CASE STUDY: Where Have All the Honeybees Gone? A 30% – 40% drop in U.S. honeybee
populations have been reported since the 1980s, with the following possible causes:
o Pesticide exposure (the wax in beehives absorbs these and other airborne toxins).
o Attacks by parasitic mites that can wipe out a colony in hours.
Chapter 8: Sustaining Biodiversity: The Species Approach
7. List the major threats to the world’s bird populations and give two reasons for protecting bird species
from extinction. Summarize environmental explorer Çağan Şekercioğlu’s contributions to our
understanding of the ecological importance of birds and threats to their extinction.
• Approximately 70% of the world’s nearly 10,000 known bird species are declining in numbers,
and much of this decline is clearly related to human activities, summarized by HIPPCO.
• Nearly 33% of the more than 800 bird species in the United States are endangered or threatened,
mostly because of habitat loss and degradation, invasive species, and climate change. Bird species
are threatened with extinction, mostly because of habitat loss, degradation, and fragmentation.
• Reasons for concern include:
o Birds are excellent environmental indicators because they live in every climate and
biome, respond quickly to environmental changes in their habitats, and are relatively easy
to track and count.
Section 8-4
8. What is the key concept for this section? Name two international treaties that are used to help protect
species. What is the U.S. Endangered Species Act? How successful has it been, and why is it
controversial?
• CONCEPT 8-4 We can reduce the rising rate of species extinction and help to protect overall
biodiversity by establishing and enforcing national environmental laws and international treaties,
creating a variety of protected wildlife sanctuaries, and taking precautionary measures to prevent
such harm.
Instructor’s Manual for Environmental Science, 15th edition
• In 2010, the ESA also protected an additional 588 species from other countries. The law requires
that all commercial shipments of wildlife and wildlife products enter or leave the United States
through one of nine designated ports. However, the 120 full-time USFWS inspectors can inspect
only a small fraction of the more than 200 million wild animals brought legally into the United
States annually. Each year, tens of millions of wild animals are also brought in illegally, but few
illegal shipments of endangered or threatened animals or plants are confiscated. Even when they
are caught, many violators are not prosecuted, and convicted violators often pay only a small fine.
• The ESA is probably the most far-reaching environmental law ever adopted by any nation, which
has made it controversial. Also, it forbids federal agencies (except the Defense Department) to
9. Summarize the roles and limitations of wildlife refuges, gene banks, botanical gardens, wildlife farms,
zoos, and aquariums in protecting some species. Describe the role of captive breeding in efforts to
prevent species extinction and give an example of success in returning a nearly extinct species to the
wild. What are three important questions related to protecting wild species from extinction by human
activities?
• Wildlife refuges and other protected areas preserve habitat for endangered speciesn. 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. Problems with refuges include that activities
considered harmful to wildlife such as mining, oil drilling, and use of off-road vehicles occur in
Chapter 8: Sustaining Biodiversity: The Species Approach
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 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.
• Using limited financial and human resources to protect biodiversity based on the precautionary
principle involves dealing with three important questions:
o How do we allocate limited resources between protecting species and protecting their
habitats?
10. What are this chapter’s three big ideas? Why is it in keeping with two of the three scientific principles
of sustainability to protect honeybees and other wild species from extinction along with protecting the
ecosystem services provided by species? What two social science principles of sustainability are
involved in protecting species from extinction due to human activities?
• 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.
Critical Thinking
1. What are three aspects of your lifestyle that might directly or indirectly contribute to declines in
European honeybee populations and the endangerment of other pollinator species (Core Case Study)?
2. Give your response to the following statement: “Eventually, all species become extinct. So it does not
really matter that the world’s remaining tiger species or a tropical forest plant are endangered primarily
because of human activities.” Be honest about your reaction, and give arguments to support your
position.
Instructor’s Manual for Environmental Science, 15th edition
Answers will vary. One possible answer is given below.
3. Do you accept the ethical position that each species has the inherent right to survive without human
interference, regardless of whether it serves any useful purpose for humans? Explain. Would you
extend this right to the Anopheles mosquito, which transmits malaria, and to harmful infectious
bacteria? Explain. If your answer is no, where would you draw the line?
Answers will vary. One possible answer is given below.
Yes, every species that does exist has a right to exist without human interference. Humans have let
themselves become apart from nature and feel that they have the right to become the masters over it.
bring about an organism’s total eradication?
4. Wildlife ecologist and environmental philosopher Aldo Leopold wrote this with respect to preventing
the extinction of wild species: “To keep every cog and wheel is the first precaution of intelligent
tinkering.” Explain how this statement relates to the material in this chapter.
Aldo Leopold was speaking of the interrelatedness of species and the functionality of an intact
5. What would you do if fire ants invaded your yard and house? Explain your reasoning behind your
course of action. How might your actions affect other species or the ecosystem you are dealing with?
Stay away from the fire ants! Maybe use pheromone traps or introduce their natural predator. Find out
how they got into the area and prevent entry from reoccurring. Call a local pest control service.
6. How do you think your daily habits might contribute directly or indirectly to the extinction of some
bird species? What are three things that you think should be done to reduce the rate of extinction of
bird species?
Answers will vary but should include some of the following concepts:
7. Which of the following statements best describes your feelings toward wildlife?
(a) As long as it stays in its space, wildlife is okay.
(b) As long as I do not need its space, wildlife is okay.
(c) I have the right to use wildlife habitat to meet my own needs.
8. How might your lifestyle change if human activities were to contribute to the extinction of 25–50% of
the world’s identified species during this century? How might this affect the lives of any children or
grandchildren you eventually might have? List two aspects of your lifestyle that contribute to this
threat to the earth’s natural capital.
First, take measures to reduce population growth, as this is the root cause of many environmental
problems. Second, strictly enforce wildlife protection laws locally, nationally, and globally. Third,
educate the public about the benefits of protecting species.
Global Environmental Watch Exercise
Search for Extinction, and scroll to statistics on the portal’s page. Click on “Known Causes of Animal
Extinction since 1600.” You will find four general categories of causes. Thinking about history from
1600 through today, how do you think humans have changed their impact on species in each of these
categories? Has the impact increased or decreased over this time period? Give specific examples of
1. Complete the table by filling in the last column. For example, to calculate this value for Costa Rica,
divide the number of threatened breeding bird species by the total number of known breeding bird
Instructor’s Manual for Environmental Science, 15th edition
species and multiply the answer by 100 to get the percentage.
Threatened breeding bird species as a percentage of total breeding bird species per country.
Afghanistan: 11/181 X 100 = 6.0%
Cambodia: 19/183 X 100 = 10%
2. Arrange the countries from largest to smallest according to total land area. Does there appear to be any
correlation between the size of country and the percentage of threatened breeding bird species? Explain
your reasoning.
Country
Total Land Area in square
kilometers (square miles)
Threatened Breeding Bird
Species as per cent of Total
Number of Known Species
United States
9,633,915 (3,718,691)
11
China
9,599,445 (3,705,386)
34
India
3,288,570 (1,269,388)
16
10
22