Deck 14: The Structure of Communities

Question 1

The local ecotypes of the evening primrose

A) correspond to variation in their herbivores.
B) are independent of variation in their herbivores.
C) are independent of the variation in the environment.
D) filter the local herbivores.
E) none of the above

Answer 1

D

Question 2

In a neutral model of community structure,

A) deterministic processes organize the community.
B) species associate at random.
C) competitive effects are neutralized.
D) predation determines community structure.
E) none of the above

Answer 2

B

Question 3

If competition structures a community,

A) niche space should be neutral.
B) there is no niche overlap among species.
C) niches should be widely separated in niche space.
D) the environment does not filter species.
E) none of the above

Answer 3

C

Question 4

Communities that conform to a neutral model

A) may have been structured by competition in the past.
B) are not environmentally filtered.
C) converge on other communities.
D) have non-random positions in niche space.
E) none of the above

Question 5

Which of the following is not a prediction of the Bowers and Brown study of desert rodent communities?

A) Rodents of similar size should coexist less frequently.
B) The more similar the body sizes of two species, the less likely they should co-occur.
C) Species from different guilds are less likely to coexist.
D) Species from other guilds co-occur at random.
E) none of the above

Question 6

Niches of coexisting species

A) cannot overlap.
B) have large niche breadth.
C) occupy a small range on the resource axis.
D) are independent of past competition.
E) none of the above

Question 7

Only distantly related New World monkeys co-occur. This due to

A) phylogenetic under dispersion.
B) phylogenetic clustering.
C) competition eliminating similar species.
D) environmental filtering.
E) none of the above

Question 8

The key difference between community heritability and population heritability is that

A) the denominator in the community heritability equation is variation in a community trait.
B) the denominator in the community heritability equation is total genetic variance.
C) the denominator in the community heritability equation is additive genetic variance.
D) there is no denominator in the community heritability equation.
E) none of the above

Question 9

Ant mutualists of wild cotton are

A) more protective when herbivores are absent.
B) more protective when herbivores are present.
C) more diverse when nectar production is high.
D) less diverse when nectar production is low.
E) none of the above

Question 10

The starfish Pisaster

A) consumes barnacles, decreasing competition.
B) competitively excludes mussels.
C) suppresses algal growth.
D) benefits from the shade of kelp.
E) none of the above

Question 11

Disturbance affects community structure by

A) decreasing the resource base.
B) increasing the resource base.
C) leading to community equilibrium.
D) accelerating competitive exclusion.
E) none of the above

Question 12

According to the core-satellite hypothesis,

A) most species are common.
B) abundance and occurrence are linearly related.
C) core species are found at few sites.
D) satellite species are found in many sites surrounding core sites.
E) none of the above

Question 13

In metacommunities,

A) dispersal is unimportant.
B) competitive exclusion does not occur.
C) non-equilibrium and equilibrium processes occur.
D) have low community heritability.
E) none of the above

Question 14

Competitive networks are

A) based on apparent competition.
B) the result of facilitation.
C) due to the ghost of competition past.
D) due to keystone predators.
E) none of the above

Question 15

Tropical forests species diversity is

A) affected by environmental filtering and negative density-dependent effects.
B) affected only by environmental filtering.
C) affected only by negative density-dependent effects.
D) determined by the C:N ratio
E) none of the above

Question 16

If niches on islands are arranged at random,

A) competition will not occur.
B) niches are hyperdispersed.
C) niches are clumped.
D) they represent the null hypothesis.
E) none of the above

Question 17

Coexisting members of a guild differ in size by a factor of 1.4

Question 18

Neutral models emphasize dispersal and chance.

Question 19

Environmental filtering reduces competition.

Question 20

Phylogenetic clustering and phylogenetic overdispersion are mutually exclusive patterns.

Question 21

Desert rodents from different guilds less often than those from the same guild.

Question 22

If niches are hyperdispersed in niche space we conclude that competition structures the community.

Question 23

Core species are found in many sites but at low density.

Question 24

Invasive species are always superior competitors.

Question 25

Closely related species of oaks in Florida are more likely to occur together.

Question 26

Communities differ from populations in that they have precise boundaries.

Question 27

Explain the difference between a competitive hierarchy and a competitive network.

Question 28

A __________ increases community diversity by suppressing the populations of competitively dominant species.

Question 29

Explain the concept of the Ghost of Competition Past.

Question 30

How does disturbance affect community structure?

Question 31

Why is dispersal important in neutral models?

Question 32

Exotic species often disrupt natural communities by __________.

Question 33

Explain the concept of the null hypothesis in community structure.