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158 Chapter 5 • Study Guide

Lesson 1 evolution• Biological evolution can occur through mutation, migra-

tion, genetic drift, and natural selection. Evolution by natural selection occurs in a population when: (1) more organisms are born than can survive, (2) organisms differ in their characteristics, and (3) there is variable survival and reproduction among individuals.

• Two processes, speciation and extinction, combine to produce the diversity of life on Earth.

evolution (126) gene (126) mutation (127) genetic drift (127) natural selection (127) fitness (129) adaptation (129) artificial selection (130) speciation (131) extinction (132)

Lesson 2 Species Interactions• An organism’s niche is affected by both its tolerance and

competitive interactions.• Predation, parasitism, and herbivory are interactions in

which one species benefits, while the other is harmed.• Mutualism and commensalism are relationships in which

neither participant is harmed.

niche (133) tolerance (134) resource partitioning (135) predation (136) coevolution (137) parasitism (138) symbiosis (138) herbivory (138) mutualism (139) commensalism (140)

Lesson 3 ecological Communities• Organisms are classified as either producers or consumers

based on how they obtain energy and nutrients.• Only about 10 percent of energy is transferred from one

trophic level to the next. This inefficient energy transfer between organisms shapes the structure of a community.

• Feeding relationships have both direct and indirect effects on organisms in the community.

primary producer (141) detritivore (143) photosynthesis (142) decomposer (143) chemosynthesis (142) trophic level (144) consumer (142) biomass (145) cellular respiration (143) food chain (146) herbivore (143) food web (146) carnivore (143) keystone species (148) omnivore (143)

Lesson 4 Community Stability• Following a disturbance, communities may undergo

succession. • Without limiting factors, species introduced to a new area

can become invasive.

succession (149) secondary succession (151) primary succession (150) invasive species (153) pioneer species (150)

InquIry LABs And ActIvItIes• Simulating Adaptations Use tools and a variety of materials to model how dif-

ferent bird beaks work. Then graph the results.• Life in a Drop of Pond Water Even in a drop of water, organisms interact. Observe

and sketch microscopic producers and consumers.• Invasive Organisms Near You Research an invasive species in your area. What are its

impacts? How is it managed?

How do organisms affect one another’s survival

and environment?

Lesson 2 How do species

interact in nature?

Lesson 1 What role does the environment

play in an organism’s survival and reproduction?

Lesson 4 How do communities

respond to a disturbance?

Lesson 3 How do energy and nutrients move through communities?

STUDY RESOURCES

Chapter 5 Self Test • Chapter 5 Worksheets • Chapter 5 Overview Presentation (for PowerPoint)

Evolution and Community Ecology 159

Review Concepts and Terms 1. Which of the following is NOT a mechanism for

biological evolution? a. mutation b. genetic drift c. inheritance of acquired characteristics d. natural selection

2. What is the term scientists use to describe how reproductively successful an organism is in its environment?

a. adaptation b. fitness c. speciation d. evolution

3. “Everything an organism does and when it does it” describes an organism’s

a. tolerance. b. community. c. character displacement. d. niche.

4. Which of the following is an interaction in which one organism benefits and the other is harmed (+/–)?

a. parasitism b. mutualism c. competition d. commensalism

5. Which of the following is an interaction in which both organisms are harmed (–/–)?

a. parasitism c. competition b. predation d. commensalism

6. Which of the following types of organisms per-form photosynthesis?

a. a primary producer c. a carnivore b. an herbivore d. a detritivore

7. Which of the following organisms is a decomposer?

a. a plant c. a mushroom b. a tiger d. a deer

8. A caterpillar eats some grass. A bird eats a cat-erpillar. A fox eats a bird. Which of the follow-ing food chains represents this series of feeding relationships?

a. fox → bird → caterpillar → grass b. bird → fox → caterpillar → grass c. caterpillar → grass → bird → fox d. grass → caterpillar → bird → fox

9. Which of the following organisms is often a pio-neer species?

a. grasses b. lichen c. otters d. spruces

Modified True/False Write true if the statement is true. If it is false, change the underlined word or words to make the statement true.

10. A trait that is passed to the next generations and promotes an individual’s survival and reproduc-tion is called an adaptation.

11. Mass extinctions occur gradually, one species at a time.

12. Competition describes an interaction in which both organisms benefit.

13. Photosynthesis is the process by which primary producers use sunlight to convert oxygen and

The Central Case in this chapter focused on the impact invasive zebra mussels are having in the Great Lakes and beyond. How do you think the United States should address the problem of invasive species? Is it a local, national, or an international problem? Use examples from the Central Case to support your answer.

ANSWERS

Chapter Assessment For answers to the Chapter Assessment, see page A–8 at the back of the book.

5Chapter

Fox

HawkSnake

BirdOwl

Frog

GrasshopperMouse

Grasses

Rabbit

160 Chapter 5 • Assessment

22. Why does secondary succession proceed faster than primary succession?

Critical Thinking 23. Compare and Contrast What is the difference

between commensalism and mutualism? Give an example of each.

24. Use Analogies Are decomposers and detritivores more like a manufacturing company or a recy-cling company? Explain your answer.

25. Compare and Contrast Compare the equations for photosynthesis and cellular respiration. How are they similar? In what ways are they different?

26. Apply Concepts Examine the food web below. Describe two food chains: one with the owl as a secondary consumer, and one showing the owl as a tertiary consumer.

27. Predict A person vacationing on a tropical island discovers a plant that only grows on that island. He decides to bring it home and plant it in his New England garden. Do you think this plant will become invasive? Why or why not?

28. Apply Concepts What is a climax community? How have ecologists’ views of climax communi-ties changed?

water into sugars. 14. The organism below is a primary consumer.

Reading Comprehension Read the following selection and answer the questions that follow.Usually, large secondary or tertiary consumers near the top of a food web, such as wolves, sea stars, sharks, and sea otters, are considered keystone spe-cies. These predators control populations of herbi-vores, which, in the absence of the predators, could multiply and greatly change the plant community. However, other types of organisms also can exert strong community-wide effects. “Ecosystem engi-neers” physically modify the environment shared by community members. Beavers build dams and turn streams into ponds that flood acres of dry land and turn them to swamp. Small organisms and those toward the bottoms of food webs may have even greater impact. Remove the fungi that decompose dead matter or the insects that control plant growth, and a community may change very rapidly indeed.

15. From the passage, you can infer that organisms can be considered keystone species ONLY if they

a. are predators. b. exert strong community-wide effects. c. eat plants. d. are at the bottom of a food web.

16. Which of the following would make the BEST title for this selection?

a. “Keystone Species in Yellowstone Park” b. “Defining Trophic Levels” c. “Surprising Keystone Species” d. “Do Keystone Species Exist?”

Short Answer 17. What are the conditions of natural selection? 18. Describe the process of allopatric speciation. 19. What is symbiosis? 20. What is coevolution? 21. Why is energy transfer in a community best

visualized as a pyramid?

Ecological Footprints

Adapted from MacLucich, D.A. 1937. Fluctuation in the numbers of varying hare (Lepus americanus). University of Toronto Studies in Biology Series 43, Toronto: University of Toronto Press.

Populations of Lynx and Hare in Ontario

1850

160140120100806040200

1860

1870

1880

1890

Year

Pop

ula

tion

(in

th

ousa

nd

s)

1900

1910

1920

1930

1940

Hare

Lynx

Plants

Mammals

Birds

Mollusks

Arthropods

Microbes

Other

30.00

0.04

0.19

0.18

9.00

40.00

20.59

Percentage of Total Introduced

Number of Species Introduced

Source: Pimentel, D., 2003. Economic and ecological costs associated with aquatic invasive species. Proceedings of the Aquatic Invaders of the Delaware Estuary Symposium, Malvern, Pennsylvania, May 20, 2003.

Evolution and Community Ecology 161

Analyze DataFor nearly 100 years, scientists at the University of Toronto collected data for hare and lynx populations in Ontario, Canada. Their data are below. Use the graph to answer the questions that follow.

29. Interpret Graphs Describe the general pattern of the population curves. What kind of relationship do they show?

Read the information below. Copy the table into your notebook and record your calculations. Then, answer the questions that follow.

In 2003, scientist David Pimentel reviewed available data on the ecological and economic costs of invasive species in the United States. He estimated that the cost of controlling just the aquatic invasive species was about $9 billion a year. He also estimated that 50,000 species had been introduced to the United States in the proportions shown in the table. Use this information to fill in the table. 1. About how many more invasive species in the

United States are plants than mammals? 2. If zebra and quagga mussels represent 11% of the

cost to control aquatic invaders, about how much money per year is spent on them?

3. Why do you think there are so many more inva-sive plants than invasive mammals and birds?

30. Infer Do you think sampling techniques were used to collect this population data? Explain your reasoning.

31. Predict Suppose a viral infection killed off most of the lynx around 1910. How would the hare population curve differ from the one shown?

32. Analyze Graphs Using only the information in the graph, what caused the drop in the hare population between 1865 and 1870?

Write About It 33. Creative Writing The local aquarium wants your

help explaining to the public the importance of sea otters in kelp forest ecosystems. Use illustra-tions and words to make a sign that could be placed in front of the sea otter exhibit. Explain the concept of “keystone species” and describe the role sea otters play in nature.

34. Apply the BIGQUESTION You have learned that competition can have big effects on organisms. Write a paragraph in which you describe a situa-tion in which competition, through the process of natural selection, leads to a change in the behav-ior or physical appearance of an organism.

MATH SUPPORT For help multiplying with percentages, see the Math Handbook.