The Structure Of Communities Test Bank Answers Chapter 14

Chapter 14 The Structure of Communities

Multiple Choice

1. The local ecotypes of the evening primrose
2. correspond to variation in their herbivores.
3. are independent of variation in their herbivores.
4. are independent of the variation in the environment.
5. filter the local herbivores.
6. none of the above
7. In a neutral model of community structure,
8. deterministic processes organize the community.
9. species associate at random.
10. competitive effects are neutralized.
11. predation determines community structure.
12. none of the above
13. If competition structures a community,
14. niche space should be neutral.
15. there is no niche overlap among species.
16. niches should be widely separated in niche space.
17. the environment does not filter species.
18. none of the above
19. Communities that conform to a neutral model
20. may have been structured by competition in the past.
21. are not environmentally filtered.
22. converge on other communities.
23. have non-random positions in niche space.
24. none of the above
25. Which of the following is not a prediction of the Bowers and Brown study of desert rodent communities?
26. Rodents of similar size should coexist less frequently.
27. The more similar the body sizes of two species, the less likely they should co-occur.
28. Species from different guilds are less likely to coexist.
29. Species from other guilds co-occur at random.
30. none of the above
31. Niches of coexisting species
32. cannot overlap.
33. have large niche breadth.
34. occupy a small range on the resource axis.
35. are independent of past competition.
36. none of the above
37. Only distantly related New World monkeys co-occur. This due to
38. phylogenetic under dispersion.
39. phylogenetic clustering.
40. competition eliminating similar species.
41. environmental filtering.
42. none of the above
43. The key difference between community heritability and population heritability is that
44. the denominator in the community heritability equation is variation in a community trait.
45. the denominator in the community heritability equation is total genetic variance.
46. the denominator in the community heritability equation is additive genetic variance.
47. there is no denominator in the community heritability equation.
48. none of the above
49. Ant mutualists of wild cotton are
50. more protective when herbivores are absent.
51. more protective when herbivores are present.
52. more diverse when nectar production is high.
53. less diverse when nectar production is low.
54. none of the above
55. The starfish Pisaster
56. consumes barnacles, decreasing competition.
57. competitively excludes mussels.
58. suppresses algal growth.
59. benefits from the shade of kelp.
60. none of the above
61. Disturbance affects community structure by
62. decreasing the resource base.
63. increasing the resource base.
64. leading to community equilibrium.
65. accelerating competitive exclusion.
66. none of the above
67. According to the core-satellite hypothesis,
68. most species are common.
69. abundance and occurrence are linearly related.
70. core species are found at few sites.
71. satellite species are found in many sites surrounding core sites.
72. none of the above

13. In metacommunities,

1. dispersal is unimportant.
2. competitive exclusion does not occur.
3. non-equilibrium and equilibrium processes occur.
4. have low community heritability.
5. none of the above

14. Competitive networks are

1. based on apparent competition.
2. the result of facilitation.
3. due to the ghost of competition past.
4. due to keystone predators.
5. none of the above

15. Tropical forests species diversity is

1. affected by environmental filtering and negative density-dependent effects.
2. affected only by environmental filtering.
3. affected only by negative density-dependent effects.
4. determined by the C:N ratio
5. none of the above

16. If niches on islands are arranged at random,

1. competition will not occur.
2. niches are hyperdispersed.
3. niches are clumped.
4. they represent the null hypothesis.
5. none of the above

True/False

1. Coexisting members of a guild differ in size by a factor of 1.4
2. Neutral models emphasize dispersal and chance.
3. Environmental filtering reduces competition.
4. Phylogenetic clustering and phylogenetic overdispersion are mutually exclusive patterns.
5. Desert rodents from different guilds less often than those from the same guild.
6. If niches are hyperdispersed in niche space we conclude that competition structures the community.
7. Core species are found in many sites but at low density.
8. Invasive species are always superior competitors.
9. Closely related species of oaks in Florida are more likely to occur together.
10. Communities differ from populations in that they have precise boundaries.

Short Answer/Fill in the Blank

1. Explain the difference between a competitive hierarchy and a competitive network.
2. A __________ increases community diversity by suppressing the populations of competitively dominant species.
3. Explain the concept of the Ghost of Competition Past.
4. How does disturbance affect community structure?
5. Why is dispersal important in neutral models?
6. Exotic species often disrupt natural communities by __________.
7. Explain the concept of the null hypothesis in community structure.