• Home
  • Textbooks
  • Biological Science
  • Community Ecology

Biological Science

Scott Freeman, Lizabeth Allison, Michael Black

Chapter 55

Community Ecology - all with Video Answers

Educators

Chapter Questions

02:17

Problem 1

True or false? Species act as agents of natural selection when they interact.

John Barone
John Barone
Numerade Educator
04:18

Problem 2

What is niche differentiation?
a. the evolution of traits that reduce niche overlap and competition
b. interactions that allow species to occupy their fundamental niche
c. the degree to which the niches of two species overlap
d. the claim that species with the same niche cannot coexist

John Barone
John Barone
Numerade Educator
02:42

Problem 3

The relationship between ants and treehoppers in the presence of spiders is an example of
a. commensalism.
b. competition.
c. consumption.
d. mutualism.

John Barone
John Barone
Numerade Educator
02:33

Problem 4

What is one advantage of inducible defenses?
a. They are always present; thus, an individual is always able to defend itself.
b. They make it impossible for a consumer to launch surprise attacks.
c. They result from a coevolutionary arms race.
d. They make efficient use of resources, because they are produced only when needed.

John Barone
John Barone
Numerade Educator
01:56

Problem 5

Pioneer species tend to have high _________ and lower survivorship.

John Barone
John Barone
Numerade Educator
03:09

Problem 6

Which of these factors is not generally correlated with species diversity?
a. latitude
b. productivity
c. longitude
d. island size

John Barone
John Barone
Numerade Educator
03:48

Problem 7

The text claims that species interactions are conditional and dynamic. Do you agree with this statement? Why or why not? Cite specific examples to support your answer.

John Barone
John Barone
Numerade Educator
03:53

Problem 8

Why does the phrase "coevolutionary arms race" appropriately characterize the long-term effects of species interactions?
a. Both plants and animals have evolved weapons for defense that are so effective that many plants are not eaten, and predators cannot reduce prey populations to extinction.
b. Adaptations that give one species a fitness advantage in an interaction are likely to be countered by adaptations in the other species that eliminate this advantage.
c. In all species interactions except for mutualism, at least one species loses (suffers decreased fitness).
d. Even mutualistic interactions can become parasitic if conditions change. As a result, interacting species are always "at war."

John Barone
John Barone
Numerade Educator
04:13

Problem 9

Biologists have tested the hypotheses that communities are highly predictable versus highly unpredictable. State the predictions that these hypotheses make with respect to (a) changes in the distribution of the species in a particular community over time, and (b) the communities that should develop at sites where abiotic conditions are identical. Which hypothesis appears to be more accurate?

John Barone
John Barone
Numerade Educator
03:56

Problem 10

What is a disturbance? Consider the role of fire in a forest. Compare and contrast the consequences of high-frequency versus low-frequency fire, and high versus low severity of fire.

John Barone
John Barone
Numerade Educator
02:46

Problem 11

Summarize the life-history attributes of early successional species. Why are these attributes considered adaptations?

John Barone
John Barone
Numerade Educator
03:07

Problem 12

Explain why high productivity should lead to increased species richness in habitats such as tropical rain forests and coral reefs.

John Barone
John Barone
Numerade Educator
03:39

Problem 13

Some insects harvest nectar by chewing through the wall of the structure that holds the nectar. As a result, they obtain a nectar reward, but pollination does not occur. Suppose that you observed a certain bee species obtaining nectar in this way from a particular orchid species. Over time, how might you expect the characteristics of the orchid population to change in response to this bee behavior?

John Barone
John Barone
Numerade Educator
02:34

Problem 14

You are a walking, talking community that includes trillions of bacterial and archaeal cells. Your gut, in particular, contains a complex microbial community. In some circumstances, the use of probiotics, which stimulate the rapid growth of bacteria that are mutalistic or commensal with humans, can eliminate the need to use antibiotics, which can wipe out helpful bacteria along with harmful bacteria. The use of probiotics is an example of which process?
a. succession
b. competitive exclusion
c. parasitism
d. niche differentiation

John Barone
John Barone
Numerade Educator
03:21

Problem 15

Suppose that a two-acre lawn on your college's campus is allowed to undergo succession. Describe how species traits, species interactions, and the site's history might affect the community that develops.

John Barone
John Barone
Numerade Educator
02:53

Problem 16

Design an experiment to test the hypothesis that increasing species richness increases a community's productivity.

John Barone
John Barone
Numerade Educator