Chapter 16 - Competition

Question 1

What is intraspecific competition?

Answer 1

Competition among individuals of the same species.

Question 2

What is interspecific competition?

Answer 2

Competition among individuals of different species.

Question 3

What are common resources of plants?

Answer 3

Sunlight, soil nutrients, water.

Question 4

What are resources of animals?

Answer 4

Food, water space.

Question 5

What is not considered a resource?

Answer 5

An ecological factor, such as temperature or pH, that cannot be consumed or used.

Question 6

What is a resource?

Answer 6

Anything an organism consumes or uses that causes an increase in the growth rate of a population when it becomes more available.

Question 7

What are renewable resources? Provide examples.

Answer 7

Resources that are constantly regenerated; seeds, sunlight.

Question 8

What are nonrenewable resources? Give an example.

Answer 8

Resources that are not regenerated; space.

Question 9

Where can renewable resources originate?

Answer 9

From inside or outside the ecosystem.

Question 10

How does competition impact resources that come from outside the ecosystem?

Answer 10

Can reduce their abundance but cannot affect the rate of resource supply.

Question 11

How does competition impact resources that arise from inside the ecosystem?

Answer 11

Can affect supply and demand.

Question 12

What is Liebig’s law of the minimum?

Answer 12

A population increases until the supply of the most limiting resource prevents it from increasing further.

Question 13

When two species compete for a single limiting resource, which species persists?

Answer 13

The one that can drive down the abundance to the lowest level.

Question 14

What does Liebig’s law assume?

Answer 14

If a given resource limits the growth of individuals and populations, increasing the availability of other resources will not improve this growth.

Question 15

What is the competitive exclusion principle?

Answer 15

Two species cannot coexist indefinitely when they are both limited by the same resource.

Question 16

What observations were the basis for the competitive exclusion principle?

Answer 16

Generally, one species is better at obtaining the resource or is better able to survive when the resource is scarce.

Question 17

Why do closely related species living in the same region often exist in different habitats?

Answer 17

Over the course of evolution, developed competitive advantages in their own environment.

Question 18

To add a second species to the logistic growth model, what two pieces of information do we need?

Answer 18

1. # of individuals of second species.
2. How much each individual of second species affects carrying capacity of the first species.

Question 19

What are competition coefficients?

Answer 19

Variables that convert between the number of individuals of one species and the number of individuals of another species.

Question 20

Under what two conditions does the dual species logistic growth model reach equilibrium?

Answer 20

1. When N = 0
2. When carrying capacity is reached.

Question 21

Explain the basics of what each figure is representing (a and b)

Answer 21

Figure a: Equilibrium isocline for species 1 (green line) representing the combinations of species’ 1 population size (N1) and species 2 population size (N2) that make population 1 experience zero growth.
Figure b: Equilibrium isocline for species 2 (purple line) representing the combinations of species’ 1 population size (N1) and species 2 population size (N2) that make population 2 experience zero growth.

Question 22

What is the abundance of species 1 when species 2 has an abundance of 0? What is the abundance of species 2 when species 1 has an abundance of zero? What do these values represent?

Answer 22

When species 2 has an abundance of 0, species 1 has an abundance of K1, its carrying capacity.
When species 1 has an abundance of 0, species 2 has an abundance of K2, its carrying capacity.

Question 23

What do the arrows in these figures represent?

Answer 23

Indicate how each population either increases or decreases as it moves away from the equilibrium line.

Question 24

What is a zero population growth isocline?

Answer 24

Population sizes at which a population experiences zero growth.

Question 25

Do growth rates effect the position of an isocline?

Answer 25

No, growth rates determine how quickly a population will meet equilibrium but not the location of equilibrium.

Question 26

How can we determine if one of two species will win the competitive interaction or if the two will coexist?

Answer 26

Overlap their individual zero growth population isoclines.

Question 27

What is depicted in this figure? What will happen to each population?

Answer 27

Isocline for species 1 is further than species 2. Species 1 will increase to carrying capacity K1 and species 2 will go extinct.

Question 28

What is depicted in this figure? What will happen to each population?

Answer 28

Isocline for species 2 is further than species 1. Species 2 will increase to K2 and species 1 will go extinct.

Question 29

What is depicted in this figure? What will happen to each population?

Answer 29

Isoclines cross and carrying capacities are on outermost points of the axes. Winner depends on initial population size of each species.

Question 30

What is depicted in this figure? What will happen to each population?

Answer 30

Isoclines cross and carrying capacities are on innermost points of the axes. The species will coexist.

Question 31

When is coexistence between species most likely?

Answer 31

When interspecific competition is weaker than intraspecific competition.

Question 32

When competing for two different resources, when does one species have a competitive advantage?

Answer 32

When one species is better able to sustain itself with low levels of both resources.

Question 33

When competing for two different resources, when coexistence between two species occur?

Answer 33

When one species can better sustain itself at low levels of one resource and the other species can better sustain itself at low levels of the other resource.

Question 34

What is a common trade-off related to competition?

Answer 34

Trade-off between competitive ability and the ability to tolerate a challenging abiotic factor.

Question 35

Which plants are most susceptible to herbivores? Which animals are most susceptible to predators? What can this be attributed to?

Answer 35

The most competitive plants and animals. Trade-off between resistance to predators and competitive ability.

Question 36

What is exploitative competition?

Answer 36

Competition in which individuals consume and drive down the abundance of a resource to a point that other individuals cannot exist.

Question 37

What is interference competition?

Answer 37

When competitors do not immediately consume resources but defend them.

Question 38

Is exploitative competition considered direct or indirect competition?

Answer 38

Indirect

Question 39

What is an effective form of interference competition that occurs between animal species?

Answer 39

Aggressive interactions

Question 40

What is allelopathy?

Answer 40

A type of interference that occurs when organisms use chemicals to harm their competitors.

Question 41

What is apparent competition?

Answer 41

When two species have a negative effect on each other through an enemy, including a predator, parasite or herbivore.