MILLER/SPOOLMAN, SUSTAINING THE ENVIRONMENT, 12E

CHAPTER SUMMARY

CHAPTER 4

4-1 What roles do species play in anecosystem?

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 ecologicalrole called its niche.CONCEPT 4-1B Any given species may play oneor 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, andcommensalism—affect the resource use and populationsizes of the species in an ecosystem.

  1. List two strategies that predators use to capture their prey. List at least five strategies that prey use to defend themselves against predators.
  2. Distinguish among three forms of symbiotic relationships and give one example of each: parasitism, mutualism, and commensalism.

4-3 How do communities and ecosystemsrespond to changing environmentalconditions?

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 ofecosystems change in response to changing environmentalconditions through a process called ecological succession.

  1. Define ecological succession. Distinguish between primary and secondary succession, giving an example of each.
  2. 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 growindefinitely because of limitations on resources andbecause of competition among species for those resources.

  1. 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.
  2. Briefly explain why humans are not exempt from nature’s population controls.

4-5 What factors influence the size of thehuman 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 ofbirths and immigration, and decreases through deaths andemigration.CONCEPT 4-5B The average number of children bornto women in a population (total fertility rate) is the keyfactor that determines population size.CONCEPT 4-5C The numbers of males and females inyoung, middle, and older age groups determine how fast apopulations grows or declines.

  1. Define birth rate, death rate. Write an equation to mathematically describe the relationship between these rates and the rate of population change.
  2. Distinguish between replacement-level fertility and total fertility rate. Describe how these fertility rates affect population growth.

4-6 How can we slow human populationgrowth?

Lessons from ecology can help us in sustaining the earth as we live upon it.CONCEPT 4-6 Experience indicates that the mosteffective ways to slow human population growth arefamily planning, reducing poverty, and elevating the statusof women.

  1. 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.
  2. What is family planning? Describe the roles of family planning.
  3. Compare and evaluate the population policies of India, China, and Thailand.