Deck 16: Competition

Question 1

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 1

B

Question 2

Which of the following is NOT a renewable resource?

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

Answer 2

D

Question 3

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?

Answer 3

not answered

Question 4

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 5

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

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

Question 6

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

Question 7

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 with the largest canopy.
C) the tree that can persist as saplings in deep shade in the forest understory.
D) the most abundant species of saplings in the understory.

Question 8

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 9

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

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

Question 10

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 11

Distantly related species are most likely to compete if they

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

Question 12

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 to control plants. What is a reasonable hypothesis for this result?

Question 13

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 14

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 15

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 16

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 17

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 18

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 19

Interspecific competition occurs

A) when two mountain lions 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 20

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 21

Which of the following equations is a zero-growth isocline?

A) N₂ = K₁ ÷ $\alpha$
B) N₂ = $\alpha$ ÷ K₂
C) N₁ = $\alpha$ ÷ K₁
D) N₂ = K₂ ÷ $\alpha$

Question 22

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

A) $\alpha$ = 1; $\beta$ = 1
B) $\alpha$ < 1; $\beta$ < 1
C) $\alpha$ > 1; $\beta$ > 1
D) $\alpha$ < 1; $\beta$ > 1
E) $\alpha$ > 1; $\beta$ < 1

Question 23

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 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 1,000 mice would support only 300 chipmunks. What would $\alpha$ and $\beta$ be for this population in which mice are species 1 and chipmunks are species 2?

A) $\alpha$ = 3.3; $\beta$ = 0.3
B) $\alpha$ = 0.3; $\beta$ = 3.3
C) $\alpha$ = 1.7; $\beta$ = 0.6
D) $\alpha$ = 0.6; $\beta$ = 1.7

Question 25

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 26

In Lotka-Volterra competition models, the variable K represents the

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

Question 27

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 28

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 29

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 $\alpha$ _1,2 and $\alpha$ _2,1

Question 30

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 31

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 32

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 33

In Lotka-Volterra population models, $\alpha$ ₁₂ and $\alpha$ ₂₁ are referred to as

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

Question 34

In the logistic growth equation $\frac { d N } { d t } = r N \left( 1 - \frac { N } { K } \right)$ , the variable r represents the

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

Question 35

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

Question 36

In Lotka-Volterra competition models, what does the term $\alpha$ _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 37

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 38

A zero-growth isocline is best defined in terms of

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

Question 39

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 40

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 41

The result of a chi-square test gives $\chi$ ² = 35.95, $\chi$ ² 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 42

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 43

The research on competition between sage and grasses in California demonstrated that the bare zone surrounding purple sage shrubs (Salvia leucophylla) was due to

A) foraging by small mammals and not competition.
B) apparent competition.
C) exploitative competition.
D) interference competition.

Question 44

Researchers studying sex ratios among field mice expect to find a 50:50 ratio of males to females. Instead they find 1,120 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 $\alpha$ = 0.05 and 1 degree of freedom.

Question 45

In the study of the gray partridge and ring-necked pheasant in the United Kingdom, researchers found that gray 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 46

Describe the concept of Leibig's law of the minimum and how it relates to the reality of species requirements of multiple resources for population growth.

Question 47

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 48

When organisms use chemicals to suppress competitors, it is called

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

Question 49

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 50

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 51

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

Question 52

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 53

Describe what researchers have discovered about the invasive species garlic mustard that makes the plant such an effective competitor in the forests of the northeast.

Question 54

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 55

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 56

When two species compete for soil water, it is called

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

Question 57

Species that produce chemicals for whatever reason pay a price. Whether the chemical allows them to be a more effective prey (i.e., less likely to be taken by a predator) or a better competitor, the chemical produced by the organism has a cost that must be accounted for and could have been used for other purposes (i.e., reproduction). Discuss the costs associated with garlic mustard's production of the chemical sinigrin. How should the production of the chemical change as the species residency time in a particular forested area increases? Why would this change in production make sense?

Question 58

What type of competition is allelopathy?

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

Question 59

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

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

Question 60

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 to the control fields, where the density and height of goldenrod was reduced. What did researchers conclude from this result?

Question 61

In the pine bush/pine barrens of the northeastern United States, fire suppression has seen native, fire-dependent pitch pine trees (Pinus rigida) replaced by black locust (Robinia pseudoacacia). This would be an example of the role that

A) allelopathy plays in competition.
B) disturbance plays in competition.
C) predation plays in competition.
D) herbivory plays in competition.

Question 62

A gray squirrel consuming acorns in a forest impacting other species' ability to do the same would be an example of what type of competition?

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

Question 63

According to the competitive exclusion principle, two species limited by the same resource will _____.

A) see both species coexist at large population sizes
B) see one species persist while the other dies out
C) see both species die out
D) see both species coexist at small-to-moderate population sizes

Question 64

When looking at a competitive interaction between chipmunks and gray squirrels, you determine the competition coefficient for chipmunks is 0.25. How many chipmunks would need to be added to the chipmunk population to have the same effect as adding one gray squirrel to the gray squirrel population (relative to resource use and carrying capacity)?

A) 4
B) 40
C) 25
D) 10

Question 65

Which is NOT a possible outcome of the Lotka-Volterra competition model between two species labelled x and y?

A) Species x will reach its carrying capacity and species y will go extinct.
B) Species y will reach its carrying capacity and species x will go extinct.
C) Both species x and y will go extinct.
D) Both species x and y will persist at population sizes below their respective carrying capacities.

Question 66

Black walnut trees (Juglans nigra) produce a chemical called juglone in many parts of the tree, including the roots. In producing the chemical the tree is able to decrease growth of some plants around the tree (from the trunk outward to the drip line/edge of canopy). This would be an example of what type of competition?

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

Question 67

To use the Lotka-Volterra model for competition, which of the following information is NOT needed?

A) the population sizes of both the competitive species involved
B) the intrinsic growth rate of both of the competitive species involved
C) the carrying capacities of both of the competitive species involved
D) the efficiency of conversion of resources (food items) to offspring for both of the competitive species involved