Download 4-1 What roles do species play in an ecosystem

MILLER/SPOOLMAN, SUSTAINING THE ENVIRONMENT, 12E
CHAPTER SUMMARY
CHAPTER 4
4-1 What roles do species play in an ecosystem?
All different types of species in a community—native, non-native, indicator, exotic, and alien—play different roles
in its ecology. CONCEPT 4-1A Each species plays a specific ecological role called its niche. CONCEPT 4-1B
Any given species may play one or more of five key roles—native, nonnative, indicator, keystone, or foundation—
in a particular ecosystem.
1.
Define ecological niche. Distinguish between a specialist and a generalist. Evaluate the conditions
that favor these two approaches.
2.
Explain the difference between a niche and a habitat.
3.
Distinguish among the following roles played by species and give one example of each: native
species, nonnative species, indicator species, keystone species, and foundation species. Explain why
these labels are important.
4.
Distinguish between a predator and a prey, and give an example of a predator-prey relationship.
4-2 How do species interact?
Species that share limited resources interact in five basic ways through competition, predation, parasitism,
mutualism, and commensalism. CONCEPT 4-2 Five types of species interactions—competition, predation,
parasitism, mutualism, and commensalism—affect the resource use and population sizes of the species in an
ecosystem.
5.
List two strategies that predators use to capture their prey. List at least five strategies that prey use to
defend themselves against predators.
6.
Distinguish among three forms of symbiotic relationships and give one example of each: parasitism,
mutualism, and commensalism.
4-3 How do communities and ecosystems respond to changing environmental conditions?
When environmental conditions change, one group of species is replaced by another through primary ecological
succession and secondary ecological succession. CONCEPT 4-3 The structure and species composition of
ecosystems change in response to changing environmental conditions through a process called ecological
succession.
7.
Define ecological succession. Distinguish between primary and secondary succession, giving an
example of each.
8.
List and briefly describe three ways humans affect communities.
4-4 What limits the growth of populations?
As a population reaches its carrying capacity, its growth rate will decrease; as it faces environmental pressure, the
growth will be logistic growth. CONCEPT 4-4 No population can continue to grow indefinitely because of
limitations on resources and because of competition among species for those resources.
9.
Distinguish among the biotic potential, intrinsic rate or increase, environmental resistance, carrying
capacity, exponential growth, and logistic growth of a population and use these concepts to explain
why there are always limits to population growth in nature.
10. Briefly explain why humans are not exempt from nature’s population controls.
4-5 What factors influence the size of the human population?
The size of a species’ population is influenced by the following four variables: births, deaths, immigration, and
emigration. CONCEPT 4-5A Population size increases because of births and immigration, and decreases through
deaths and emigration. CONCEPT 4-5B The average number of children born to women in a population (total
fertility rate) is the key factor that determines population size. CONCEPT 4-5C The numbers of males and females
in young, middle, and older age groups determine how fast a populations grows or declines.
11. Define birth rate, death rate. Write an equation to mathematically describe the relationship between
these rates and the rate of population change.
12. Distinguish between replacement-level fertility and total fertility rate. Describe how these fertility
rates affect population growth.
4-6 How can we slow human population growth?
MILLER/SPOOLMAN, SUSTAINING THE ENVIRONMENT, 12E
CHAPTER SUMMARY
CHAPTER 4
Lessons from ecology can help us in sustaining the earth as we live upon it. CONCEPT 4-6 Experience indicates
that the most effective ways to slow human population growth are family planning, reducing poverty, and elevating
the status of women.
13. List the four stages of the demographic transition. List social, biological, political, and economic
issues that can be addressed to help developing countries undergo a demographic transition.
14. What is family planning? Describe the roles of family planning.
15. Compare and evaluate the population policies of India, China, and Thailand.