MILLER/SPOOLMAN, SUSTAINING THE ENVIRONMENT, 12E
CHAPTER SUMMARY
CHAPTER 5
5-1 What are the trends in species extinction?
Human modification of the earth’s natural ecosystems has been extensive: reducing biodiversity, eliminating the
earth’s net primary productivity, strengthening some pest species and disease-causing bacteria, over harvesting
natural resources, etc. CONCEPT 5-1 The current rate of species extinction is at least 100 times the rate that existed
before modern humans lived on Earth (the background rate), and it is expected to increase to 1,000–10,000 times
the background rate during this century.
1. Distinguish between an endangered and a threatened species. List nine characteristics of extinctionprone species.
2. Compare past extinctions to present extinctions. Evaluate the reality of an extinction crisis.
3. Why do extinction experts consider the current estimates of species extinction to be conservative?
5-2 Why should we care about preventing premature species extinction?
Wild species have value, some of which has not yet been identified. We need a precautionary strategy to prevent
significant decrease in the genetic, species, ecological, and functional diversity of the earth. CONCEPT 5-2 We
should prevent the premature extinction of wild species because of the economic and ecological services they
provide and because they have a right to exist regardless of their usefulness to us.
4. Describe the economic, medical, scientific, ecological, aesthetic, and recreational significance of wild
species.
5. List and explain two reasons why some biologists caution us not to focus on protecting relatively large
organisms with which we are most familiar?
5-3 How do humans accelerate species extinction?
Humans can increase species extinction by causing degradation of habitat, introducing alien species, population
growth, pollution from daily activities, and by over harvesting. CONCEPT 5-3 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.
6. Briefly explain what the acronym HIPPCO stands for.
7. List and briefly describe eight ways humans increase the rate of extinction, indicating which of these
has the most impact.
8. Give two examples of the harmful effects of nonnative species that have been introduced both
deliberately and accidentally.
9. State two examples of what can be done to decrease the incidence and impacts of invasions of
nonnative species?
5-4 How can we protect wild species from extinction resulting from our activities?
Mankind must live with a precautionary principle: prevent harm even if a cause-and-effect relationship has not been
established. A low throughput economy reduces the use of matter and energy resources in reusing and recycling
nonrenewable resources, reduces unnecessary consumption, emphasizes waste reduction, encourages pollution
reduction, and controls population growth. CONCEPT 5-4A We can use existing environmental laws and treaties,
and work to enact new laws designed to prevent species extinction and to protect overall biodiversity. CONCEPT
5-4B We can help prevent species extinction by creating and maintaining wildlife refuges, gene banks, botanical
gardens, zoos, and aquariums. CONCEPT 5-4C According to the precautionary principle, we should take measures
to prevent or reduce harm to the environment and to human health, even if some of the cause-and-effect
relationships have not been scientifically established.
10. State and briefly describe the most far-reaching international treaty to protect wildlife.
11. Should the Endangered Species Act be strengthened or weakened? Defend your position.
12. Briefly assess the usefulness of wildlife refuges, gene banks, botanical gardens, and zoos in protection
of wildlife. List three qualities that should be given priority in defending wildlife.
13. List and briefly describe four things that you can do as an individual to help prevent the premature
extinction of species.
14. Describe how wildlife populations can be managed. Evaluate whose interests are generally the most
influential in determining wildlife management priorities.