Chapter 13: Interspecific Competition

Question 1

List the laboratory experiments with species interactions that supported the Lotka-Volterra model

Answer 1

1. Gause
2. Park
3. Tilman

Question 2

Let’s talk about the Gause experiments

Answer 2

Studied competition among Paramecium species:

P. aurelia + P. caudatum
P. aurelia had a higher rate of population growth and can tolerate a higher population density than P. caudatum, which died out when Gause introduced both species to one tube containing a fixed amount of bacterial food

P. caudatum + P. bursaria
These 2 species coexisted under the same conditions as the previous experiment because each used food unavailable to the other:
P. caudatum – fed on bacteria suspended in solution
P. bursaria – fed on bacteria at the bottom of the tubes

Question 3

Let’s talk about the Park experiments

Answer 3

Studied competition between Tribolium (flour beetle) species:

T. castaneum + T. confusum
The outcome of competition between the 2 depended on environmental temperature, humidity, and fluctuations in the total number of eggs, larvae, pupae, and adults

Often, the outcome of competition was not determined until many generations had passed

Question 4

Let’s talk about the Tilman experiments

Answer 4

Studied competition between 2 diatom species:

Asterionella Formosa + Synedra ulna
When grown alone in a liquid medium to which silica was continually added, both kept silica at a low level because they used it to form cell walls

However, when grown together, the use of silica by S. ulna reduced the concentration to a level below that necessary for A. formosa to survive and reproduce

By reducing resource availability, S. ulna drove A. formosa to extinction

Question 5

Hypothesis that when two or more species coexist using the same resource, one must displace or exclude the other

Answer 5

competitive exclusion principle

Question 6

Niche expansion in response to reduced interspecific competition

Answer 6

competitive release

Question 7

When species that share the same habitat coexist because each species exploits a portion of the resources unavailable to others

It is often viewed as a product of the coevolution of characteristics that function to reduce competition

Answer 7

resource partitioning

Question 8

Differences in the range of resources used or environmental tolerances

Answer 8

niche differentiation

Question 9

The principle that two species are more different where they occur together than where they are separated geographically

Answer 9

character displacement

Question 10

Effect of metabolic products of plants (excluding microorganisms) on the growth and development of other nearby plants

Answer 10

allelopathy

Question 11

Let’s talk about coyotes and wolves

Answer 11

The decline of gray wolf populations throughout much of North America have been paralleled by a dramatic expansion in the range of coyotes

Evidence from areas in which wolves have been reintroduced suggests that the expansion of coyotes was in part a result of competitive release from wolf populations over the past century