Deck 16: Competition

Question 1

Which of the following is NOT a renewable resource for a species of predatory bird?

A) prey
B) water
C) oxygen
D) nest sites

Answer 1

D

Question 2

Which of the following is NOT an example of a resource?

A) temperature
B) holes that allow prey to hide from a predator
C) soil nitrogen
D) nesting sites in a dead tree

Answer 2

A

Question 3

Which of the following is a limiting resource for sessile organisms in rocky intertidal habitats?

A) food
B) space
C) dissolved nitrogen
D) mates

Answer 3

B

Question 4

Intraspecific competition occurs

A) when any two species compete for a limited resource.
B) when two species of hummingbird compete for nectar.
C) when bald eagles compete for fish out of the same lake.
D) only among plant species.

Question 5

Closely related species

A) often share similar niches.
B) are unlikely to compete with one another.
C) are often distributed among different habitats to minimize competition.
D) grow together because they thrive in similar habitats.

Question 6

The competitive exclusion principle states that two organisms cannot coexist indefinitely when they

A) live in the same habitat.
B) are similar species.
C) are limited by the same resources.
D) consume the same prey.

Question 7

Tansley's experiments with bedstraw (Galium) showed that closely related species reduce competition by

A) partitioning soil resources.
B) growing in distinct patches.
C) growing in distinct habitats.
D) altering nutrient requirements so that there is no overlap.

Question 8

Distantly related species are most likely to compete if they

A) consume a shared limiting resource.
B) live close together.
C) live in similar habitat.
D) face the same predator species.

Question 9

In the study of the diatoms Synedra and Asterionella, Synedra was a better competitor than Asterionella because Synedra

A) had a higher carrying capacity than Asterionella.
B) had a lower carrying capacity than Asterionella.
C) reduced the shared limiting resource to the lowest level at its carrying capacity.
D) was more tolerant of predators than Asterionella.

Question 10

Leibig's law of the minimum

A) fails to consider that the interaction of resources can limit growth.
B) fails to consider competition for resources.
C) assumes that the resource in lowest supply is always the most limiting.
D) fails to consider other processes like predation and disease.

Question 11

In the study of seed-eating rodents and ants in the American Southwest deserts, which observation provided evidence that rodents and ants compete for food?

A) The two animals consume some of the same food.
B) Rodents eat larger seeds than ants.
C) Ants hide whenever rodents are present.
D) The abundance of ant colonies increases when rodents are excluded.

Question 12

Interspecific competition occurs

A) when two pumas compete for deer.
B) when any two species compete for a limited resource.
C) when bald eagles compete for fish out of the same lake.
D) only among animal species.

Question 13

Abiotic environmental factors are NOT considered resources for all of these reasons EXCEPT that

A) organisms do not compete for them.
B) they cannot be consumed.
C) they cannot be used up.
D) they do not affect growth and reproduction.

Question 14

Hemlocks cast much deeper shade than birch trees. The tree that competes more successfully for light is

A) hemlock, because it casts deeper shade.
B) the tree that survives best under low levels of light.
C) the tree that can persist as saplings in deep shade in the forest understorey.
D) the most abundant species of saplings in the understorey.

Question 15

Darwin argued that closely related species are more likely to compete because

A) they almost always live close together.
B) they are the same size.
C) they face the same predators.
D) they have similar traits and consume similar resources.

Question 16

Which of the following is NOT a renewable resource?

A) soil nitrogen
B) water
C) prey
D) space

Question 17

If a plant is primarily limited by nitrogen and secondarily by phosphorus, according to Leibig's law of the minimum, under which circumstances would adding phosphorus increase the plant's growth rate?

A) if nitrogen and phosphorus are added together
B) if the phosphorus is added to alleviate limitation before the nitrogen is added
C) if the nitrogen is added to alleviate limitation before phosphorus is added
D) Phosphorus would never increase the growth rate because the primary limitation is nitrogen.

Question 18

Organisms often have specific environmental requirements. For example, many organisms can live only within a narrow range of temperatures, nutrient levels, pH, humidity, soil moisture, and soil type. They require specific nesting sites, mates, and prey. Which (if any) of these factors are considered resources? What distinguishes resources from the other environmental factors?

Question 19

Tansley's experiments with bedstraw (Galium) showed that when two closely related species of bedstraw are grown together,

A) one is always the superior competitor regardless of habitat.
B) bedstraw in its preferred soil type is always the superior competitor.
C) bedstraw in its preferred soil type is the better competitor for soil nitrogen.
D) one was a better competitor for light and the other for water, depending on soil type.

Question 20

In the study of seed-eating rodents and ants in the American Southwest deserts, it was originally thought that rodents and ants would not compete for resources because

A) rodents often consume ants, thereby keeping ant densities very low.
B) ants are predators, and the rodents are herbivores.
C) rodents are much larger than ants.
D) rodents were active during the day and ants were active at night.

Question 21

Competition coefficients can be used to

A) identify which limiting resource two species compete for.
B) determine the time it takes for the competitive exclusion principle to operate.
C) determine whether species are likely to coexist.
D) convert between the number of individuals of one species and the number of individuals of another species.

Question 22

Populations approach a stable equilibrium when

A) all resources have been consumed.
B) resources are plentiful relative to demand.
C) growth rate nears zero.
D) the population exceeds carrying capacity.

Question 23

In experiments with competitive barnacle species distributed along upper and lower intertidal zones, researchers found a trade-off between ability to _____ and ability to _____.

A) compete; colonize
B) compete; tolerate desiccation
C) compete; tolerate strong tides
D) tolerate harsh dry conditions; colonize deeper water

Question 24

Imagine a population of 600 mice and 350 chipmunks. The chipmunks and mice eat some of the same food, but the food to support 1000 mice would support only 300 chipmunks. What would α and β be for this population in which mice are species 1 and chipmunks are species 2?

A) α = 3.3; β = 0.3
B) α = 0.3; β = 3.3β
C) α = 1.7; β = 0.6
D) α = 0.6; β = 1.7

Question 25

A zero growth isocline is best defined in terms of

A) time.
B) population.
C) carrying capacity.
D) growth rate.

Question 26

In the logistic growth equation , the variable r represents

A) the carrying capacity.
B) the intrinsic growth rate.
C) the size of the population.
D) the competition coefficient.

Question 27

If an individual of species 2 has a greater effect on species 1 than the reverse, which of the following would be true?

A) α = 1; β = 1
B) α < 1; β < 1
C) α > 1; β > 1
D) α < 1; β > 1
E) α > 1; β < 1

Question 28

Graphical models of competition tell us that

A) closely related species are less likely to compete than distantly related species.
B) closely related species are more likely to compete than distantly related species.
C) coexistence of two competing species is most likely if intraspecific competition is stronger than interspecific competition.
D) coexistence of two competing species is most likely if interspecific competition is stronger than intraspecific competition.

Question 29

In Lotka-Volterra population models, α₁₂ and α₂₁ are referred to as

A) isoclines.
B) competition coefficients.
C) carrying capacities.
D) rates of growth.

Question 30

Question: You want to perform a field experiment to determine whether green frog and bullfrog tadpoles that were laid as eggs in the same pond will coexist or one species will drive the other to extinction. You determine that a bullfrog tadpole consumes 5 times more algae than a green frog tadpole. You then determine the carrying capacity of the pond for each species based on intraspecific competition of both species: the carrying capacity for bullfrog tadpoles is 100 individuals, and the carrying capacity for green frog tadpoles is 150 individuals. You take a census of the pond and find that there are 50 bullfrog tadpoles and 200 green frog tadpoles living in the pond. Based on this information and assuming that no factors other than competition influence these populations, how will they affect each other? Will the two species coexist, or will one of these species drive the other to extinction? Explain your answer.

Question 31

Topic: competition for a single resource
Difficulty: medium
The resource requirements of two plant species, A and B, have been carefully studied. Researchers have determined the levels of a particular resource that will support equilibrium levels of each species. Species A needs more of this resource to maintain equilibrium than does species B. When these two species are set in competition (under conditions in which this resource is limiting), what is likely to happen to the populations of species A and B?

A) Species A will displace species B.
B) Species B will displace species A.
C) Species A and B will continue to coexist.
D) There is not enough information to determine the outcome.

Question 32

In Lotka-Volterra competition models, the variable K represents

A) the size of the population.
B) the intrinsic growth rate.
C) the carrying capacity.
D) the time component of the model.

Question 33

Which of the following make(s) coexistence of species 1 and 2 more likely?

A) higher values of both r1 and r2
B) lower values of both N1 and N2
C) higher values of both K2 and K1
D) lower values of both α1,2 and α2,1

Question 34

In Connell's experiment with upper and lower intertidal barnacles, the rock barnacle excluded the Poli's stellate barnacle from deeper water because

A) it was the better competitor for a limiting nutrient at that depth.
B) intraspecific competition was stronger than interspecific competition.
C) it could survive for long periods underwater.
D) it grew faster and pushed the stellate barnacle off the rock substrate.

Question 35

In Lotka-Volterra competition models, what does the term α_1,2 N₂ represent?

A) instantaneous rate of population increase of species 1
B) carrying capacity of the environment for species 1
C) reduction of species 1's carrying capacity by individuals of species 1
D) reduction of species 1's carrying capacity by individuals of species 2

Question 36

Which of the following equations is a zero growth isocline?

A) N2 = K1 ÷ α
B) N2 = α ÷ K2
C) N1 = α ÷ K1
D) N2 = K1 ÷ α

Question 37

The mathematical models for competition between species are based on the _____ equation.

A) energy balance
B) exponential population growth
C) logistic population growth
D) life table

Question 38

In David Tilman's experiments with the diatoms Cyclotella and Asterionella, when the diatoms were grown at silicon/phosphorus ratios between 6 and 90, why did the two species coexist?

A) Both species were phosphorus limited.
B) Both species were silicon limited.
C) Neither species was limited by phosphorus or silicon.
D) One species was limited by phosphorus, and the other was limited by silicon.
E) Tilman continually supplemented the cultures with individuals of the two species.

Question 39

(Figure 16.8c and d) Compare the outcomes of competition between species 1 and 2 in the figure. Justify your answers.

Question 40

Researchers perform an experiment on a long-lived perennial shrub in a semiarid site where the soil is low in nitrogen. They fertilize the plants with nitrogen, but the treated plants do not increase their growth compared with control plants. What is a reasonable hypothesis for this result?

Question 41

In the example of competition dynamics with longleaf pine (Pinus palustris) and other woody plants, fire suppression

A) caused increases in important herbivore predators of longleaf pine.
B) allowed the persistence of superior competing species that would otherwise be eliminated by fire.
C) allowed increased growth of wiregrass (Aristida beyrichiana).
D) decreased germination of longleaf pine, which requires heat from fire.

Question 42

What type of competition is allelopathy?

A) exploitative
B) interference
C) apparent
D) scramble

Question 43

Connell's research on competition between the rock barnacle and Poli's stellate barnacle in upper and lower intertidal zones is an example of

A) a manipulative experiment.
B) a long-term observational study.
C) how predation determines the superior competitor.
D) how colonization determines where species live in an intertidal zone.

Question 44

(Figure 16.17) In the study of the grey partridge and ring-necked pheasant in the United Kingdom, researchers found that grey partridges were declining. A parasitic nematode seemed to negatively affect partridges. The pheasants that carried the parasites were not negatively affected. Researchers performed an experiment in which they allowed both species to feed in one of two enclosures: enclosures with parasite eggs scattered on the floor or enclosures without parasite eggs. The results are shown in the nearby figure. What did the researchers conclude? Was competition occurring, and if so what type?

Question 45

Researchers studying sex ratios among field mice expect to find a 50:50 ratio of males to females. Instead they find 1120 females and 975 males at their site. Use a chi-square analysis to determine whether the field mouse population at their site significantly differs from a 50:50 sex ratio. Assume a critical chi-square value of 3.841 for α = 0.05 and 1 degree of freedom.

Question 46

In the experiment in which goldenrod fields were either sprayed with insecticide or left as untreated controls, the treated goldenrod increased growth and shaded out all of the other species. The result was near monocultures of goldenrod in the treated fields compared with the control fields, where the density and height of goldenrod was reduced. What did researchers conclude from this result?

Question 47

When wolves and coyotes compete, reductions in numbers of coyotes are attributed to a virus the wolves carry that is more harmful in coyotes. This is an example of

A) apparent competition.
B) exploitative competition.
C) interference competition.
D) allelopathy.

Question 48

In a chi-square test what is the null hypothesis?

A) There is no difference between expected and observed.
B) Observed and expected are different.
C) Observed is greater than expected.
D) Observed is less than expected.

Question 49

Researchers studying the effects of hay-scented fern on the recruitment of red maple and sugar maple expected to find that the fern employed interference competition on the tree seedlings by casting shade. What did researchers actually discover when they employed fences to exclude rodents?

Question 50

Scientists believe that some species of eucalyptus in Australia promote frequent fires by means of flammable oils in their leaf litter. These fires kill completing plants. What type of competition does this example describe?

A) exploitative competition
B) allelopathy
C) scramble competition
D) apparent competition

Question 51

In an experiment involving seed-eating ants and rodents in Arizona deserts, the exclusion of rodents caused an increase in the number of ant colonies over the first few years. However, over many decades the number of ant colonies actually declined. Plant diversity also declined. Why did this occur?

Question 52

When long-legged ants plug the nest entrances of red harvester ants with which they compete for seeds, it is called

A) allelopathy.
B) exploitative competition.
C) interference competition.
D) apparent competition.

Question 53

You are studying the competitive interactions between two desert plant species, the prickly pear cactus and the ocotillo. During your research, you discover that the ocotillo produces a flower that is preferentially consumed by mule deer, a major desert herbivore. When the deer population is large and has consumed most of the available ocotillo flowers, it eats the flowers of the prickly pear cactus, which reduces the prickly pear's fecundity. Further, you know that the ocotillo and prickly pear compete for water, nutrients, and light. You also discover that the prickly pear secretes a chemical into the soil that inhibits the growth and survival of the ocotillo. For each of these examples of competition between the prickly pear cactus and the ocotillo, name and describe what type of competitive interaction is taking place.

Question 54

When two species compete for soil water, it is called

A) exploitative competition.
B) interference competition.
C) apparent competition.
D) allelopathy.

Question 55

The result of a chi-square test gives χ² = 35.95, χ² critical = 14.98. What is the conclusion of the analysis?

A) null hypothesis retained
B) alternative hypothesis not supported
C) null hypothesis rejected
D) There is not enough information to make a determination.

Question 56

In Morin's competition experiment, ponds contained tadpoles of three species and a species of newt. Newts in increasing numbers were added to ponds containing the tadpoles. How did the number of newts affect competition among tadpoles?

A) Predation by newts reversed the outcome of competition between the tadpoles.
B) Predation by newts extirpated tadpoles in the ponds.
C) Predation by newts had no effect on tadpoles in the ponds.
D) Predation by newts equalized tadpole survival between the tadpoles.

Question 57

When an individual drives down a resource to a point where another individual cannot persist, it is called

A) interference competition.
B) allelopathy.
C) apparent competition.
D) exploitative competition.

Question 58

When two species interact directly to aggressively defend resources, it is called

A) allelopathy.
B) exploitative competition.
C) interference competition.
D) apparent competition.

Question 59

When organisms use chemicals to suppress competitors, it is called

A) exploitative competition.
B) interference competition.
C) apparent competition.
D) allelopathy.

Question 60

Researchers have determined that common reed damages roots of other species by secreting gallic acid. This is an example of _____ competition.

A) passive
B) exploitative
C) interference
D) apparent