1. Chapter 20 Table of Contents Section 1 Species Interactions
Community Ecology
Table of Contents
Section 1 Species Interactions
Section 2 Patterns in Communities

2. Section 1 Species Interactions
Chapter 20
Objectives
Identify two types of predator adaptations and two types of prey adaptations.
Identify possible causes and results of interspecific competition.
Compare parasitism, mutualism, and commensalism, and give one example of each.

3. Section 1 Species Interactions
Chapter 20
Predation
Predation is an interaction in which one organism (the predator) captures and eats all or part of another individual organism (the prey).

4. Chapter 20 Predation, continued Predator Adaptations
Section 1 Species Interactions
Chapter 20
Predation, continued
Predator Adaptations
Predators have adaptations to efficiently capture prey, whereas prey species have adaptations to avoid capture.

5. Chapter 20 Predation, continued Adaptations in Animal Prey
Section 1 Species Interactions
Chapter 20
Predation, continued
Adaptations in Animal Prey
Mimicry is an adaptation in which a species gains an advantage by resembling another species or object.

6. Chapter 20 Predation, continued Adaptations in Plant Prey
Section 1 Species Interactions
Chapter 20
Predation, continued
Adaptations in Plant Prey
Many plants produce secondary compounds as a chemical defense.

7. Chapter 20 Competition Competitive Exclusion
Section 1 Species Interactions
Chapter 20
Competition
Competitive Exclusion
Competition may cause competitive exclusion, the elimination of one species in a community.

8. Effect of Competition on Two Species of Barnacles
Section 1 Species Interactions
Chapter 20
Effect of Competition on Two Species of Barnacles

9. Competition, continued
Section 1 Species Interactions
Chapter 20
Competition, continued
Character Displacement
Competition may drive the evolution of niche differences among competitors. This evolution of differences in a characteristic due to competition is called character displacement.

10. Competition, continued
Section 1 Species Interactions
Chapter 20
Competition, continued
Resource Partitioning
Differential resource use to avoid competition is called resource partitioning.

11. Warbler Foraging Zones
Section 1 Species Interactions
Chapter 20
Warbler Foraging Zones

12. Chapter 20 Symbiosis Parasitism
Section 1 Species Interactions
Chapter 20
Symbiosis
Parasitism
In parasitism, one species (the parasite) feeds on, but does not always kill, another species (the host).

13. Chapter 20 Symbiosis, continued Mutualism
Section 1 Species Interactions
Chapter 20
Symbiosis, continued
Mutualism
In mutualism, both interacting species benefit.

14. Chapter 20 Symbiosis, continued Commensalism
Section 1 Species Interactions
Chapter 20
Symbiosis, continued
Commensalism
In commensalism, one species benefits, and the other is not affected.

15. Section 2 Patterns in Communities
Chapter 20
Objectives
Describe the factors that affect species richness in a community.
Explain how disturbances affect community stability.
Distinguish between types of succession, and explain why succession may not be predictable.

16. Chapter 20 Species Richness
Section 2 Patterns in Communities
Chapter 20
Species Richness
Species richness is the number of species in a community.
Species evenness is the relative abundance of each species.

17. Species Richness, continued
Section 2 Patterns in Communities
Chapter 20
Species Richness, continued
Latitude and Species Richness
In general, species richness is greatest near the equator, and larger areas support more species.

18. Species Richness, continued
Section 2 Patterns in Communities
Chapter 20
Species Richness, continued
Species Interactions and Species Richness
Species interactions such as predation can promote species richness.

19. Species Richness, continued
Section 2 Patterns in Communities
Chapter 20
Species Richness, continued
Community Stability and Species Richness
Disturbances can alter a community by eliminating or removing organisms or altering resource availability.
Species richness may improve a community’s stability.
Areas of low species richness may be less stable in the event of an ecological disturbance.

20. Successional Changes in Communities
Section 2 Patterns in Communities
Chapter 20
Successional Changes in Communities
Ecological succession is a change in the species composition of a community over time.

21. Successional Changes in Communities, continued
Section 2 Patterns in Communities
Chapter 20
Successional Changes in Communities, continued
Primary Succession
Primary succession is the assembly of a community on newly created habitat.
Primary succession occurs in areas that have been recently exposed to the elements and lack soil.

22. Successional Changes in Communities, continued
Section 2 Patterns in Communities
Chapter 20
Successional Changes in Communities, continued
Secondary Succession
Secondary succession is the change in an existing community following a disturbance.
Secondary succession occurs in areas where the original ecosystem has been cleared by a disturbance.

23. The Complexity of Succession
Section 2 Patterns in Communities
Chapter 20
The Complexity of Succession
The traditional description of succession is that the community proceeds through a predictable series of stages until it reaches a stable end point, called the climax community.
Primary succession typically proceeds from lichens and mosses to a climax community.
Secondary succession typically proceeds from weeds to a climax community.

24. Ecological Succession at Glacier Bay
Section 2 Patterns in Communities
Chapter 20
Ecological Succession at Glacier Bay

25. Ecological Succession
Section 2 Patterns in Communities
Chapter 20
Ecological Succession

26. Chapter 20 Multiple Choice
Standardized Test Prep
Multiple Choice
1. A certain tropical tree has a fruit that is eaten by only one species of bats. As the bat digests the fruit, the seeds are made ready to sprout. When the bat excretes the wastes of the fruit, it drops seeds in new locations. Which of the following is the correct term for the relationship between the bat and the tree?
A. predation
B. mutualism
C. competition
D. commensalism

27. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
1. A certain tropical tree has a fruit that is eaten by only one species of bats. As the bat digests the fruit, the seeds are made ready to sprout. When the bat excretes the wastes of the fruit, it drops seeds in new locations. Which of the following is the correct term for the relationship between the bat and the tree?
A. predation
B. mutualism
C. competition
D. commensalism

28. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
2. Which of the following is a parasite?
F. a lion hunting a zebra
G. a deer grazing on grass
H. a tick sucking blood from a dog
J. a snake swallowing a bird’s egg

29. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
2. Which of the following is a parasite?
F. a lion hunting a zebra
G. a deer grazing on grass
H. a tick sucking blood from a dog
J. a snake swallowing a bird’s egg

30. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
3. Three species of birds forage for insects in the same tree. However, each species tends to forage in different parts of the tree. This pattern of foraging is best explained as an adaptation to which of the following relationships?
A. predation
B. mutualism
C. competition
D. commensalism

31. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
3. Three species of birds forage for insects in the same tree. However, each species tends to forage in different parts of the tree. This pattern of foraging is best explained as an adaptation to which of the following relationships?
A. predation
B. mutualism
C. competition
D. commensalism

32. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
Use the map below to answer question 4. The map shows two islands.

33. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
4. What can you infer about the number of species on each of these islands?
F. Island A has more species.
G. Island B has more species.
H. Island A and Island B will have the same number of species.
J. Both islands will have fewer species than islands that are located farther north.

34. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
4. What can you infer about the number of species on each of these islands?
F. Island A has more species.
G. Island B has more species.
H. Island A and Island B will have the same number of species.
J. Both islands will have fewer species than islands that are located farther north.

35. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
Complete the following analogy:
5. predator : prey :: herbivore :
A. carnivore
B. plant
C. parasite
D. predation

36. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
Complete the following analogy:
5. predator : prey :: herbivore :
A. carnivore
B. plant
C. parasite
D. predation

37. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
Use the graph below to answer question 6. The shading in the graph indicates the frequency with which a certain bird species obtains prey, by prey size and location.

38. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
6. Which of the following statements is best supported by this graph?
F. Most often, the bird eats insects.
G. Most often, the bird nests above ground.
H. Most often, the bird finds prey at ground level.
J. Most often, the bird eats prey that is between 3 and 5 mm long.

39. Multiple Choice, continued
Chapter 20
Standardized Test Prep
Multiple Choice, continued
6. Which of the following statements is best supported by this graph?
F. Most often, the bird eats insects.
G. Most often, the bird nests above ground.
H. Most often, the bird finds prey at ground level.
J. Most often, the bird eats prey that is between 3 and 5 mm long.

40. Chapter 20 Short Response
Standardized Test Prep
Short Response
Some plants produce chemicals that are irritating or poisonous to some animals.
Explain the role of these adaptations in an ecological community.

41. Short Response, continued
Chapter 20
Standardized Test Prep
Short Response, continued
Some plants produce chemicals that are irritating or poisonous to some animals.
Explain the role of these adaptations in an ecological community.
Answer: Secondary compounds are defensive chemicals synthesized by plants to prevent plants from being eaten. Strychnine and nicotine are two examples.

42. Chapter 20 Extended Response
Standardized Test Prep
Extended Response
Base your answers to parts A & B on the information below.
The gradual, sequential change in species in an area is called ecological succession.
Part A Describe the stages of primary succession.
Part B Compare primary succession and secondary succession.

43. Extended Response, continued
Chapter 20
Standardized Test Prep
Extended Response, continued
Answer:
Part A Primary succession starts with the exposure of bare land. Lichens colonize the rock. Decaying lichens as well as minerals from the rock lead to soil formation. Soil leads to colonization by pioneer species, such as moss and weeds. Large plants, such as shrubs and trees, replace pioneer species. Various trees become dominant, and succession ends with a mature forest.
Part B Primary succession occurs when bare rock is exposed by geological events, such as island formation or glacier retreat. Secondary succession occurs after a disturbance clears away an existing community, but the soil remains intact.