Question 1

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

Accepted Answer

The replacement of pitch pine trees with black locust is likely due to the suppression of fires, which are important disturbances in maintaining the pitch pine ecosystem. Pitch pine trees are adapted to survive and even thrive in the presence of fires, while black locust is not as well-adapted and can outcompete pitch pine in the absence of fire. This demonstrates the important role that disturbance plays in competition.

Question 2

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?

Accepted Answer

Exploitative competition occurs when one species reduces the availability of a resource by consuming or using it, as in the case of a gray squirrel consuming acorns, thereby impacting other species' ability to access the same resource.

Question 3

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

Accepted Answer

The competitive exclusion principle states that two species competing for the same limiting resource cannot coexist indefinitely. One species will eventually outcompete the other and drive it to extinction or force it to evolve to use a different resource. Therefore, the most likely outcome is that one species persists while the other dies out.

Question 4

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)?

Accepted Answer

The competition coefficient (α) is defined as the effect of one species on the population growth rate of another species, relative to the effect of its own population density on its own growth rate. In this case, if the competition coefficient for chipmunks is 0.25, it means that one gray squirrel has the same competitive effect as four chipmunks. Therefore, to match the effect of one gray squirrel, four chipmunks would need to be added to the chipmunk population. Answer choice A) 4 is the correct choice.

Question 5

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

Accepted Answer

The Lotka-Volterra competition model predicts outcomes of species interactions including coexistence below carrying capacities and competitive exclusion (one species outcompeting the other), but it does not predict mutual extinction as an outcome of competition.

Question 6

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?

Accepted Answer

Interference competition occurs when one species directly interacts with and limits the growth or survival of another species. In this case, the black walnut tree is producing juglone which directly interferes with the growth of plants around it.

Question 7

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

Accepted Answer

The Lotka-Volterra model for competition only requires information on population sizes, intrinsic growth rates, and carrying capacities of the two species involved. The efficiency of conversion of resources to offspring is not necessary for the model.

Quiz 16: Competition

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

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

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

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