Ecology - Lecture 08 - Competition

Front 1

Define:

Interspecific competition

Back 1

Two species use the same resource or seek that resource to the detriment of both species.

Front 2

The 2 types of competition are:

Back 2

1) Exploitation competition

2) Interference competition

Front 3

Define:

Competitive Exclusion Principle

Back 3

Two species cannot coexist indefinitely on the same limiting resource.

i.e. "Complete competitors" cannot exist.

Front 4

Describe Gause's Paramecium experiments:

Back 4

1) Species were growth alone, and then together

2) Results:
a) Reduced equilibrium density for p. aurelia

b) p. caudatum went extinct.

Front 5

What are the 3 possible outcomes for the Lotka-Voltera Model of Competition?

Back 5

1) Species 1 goes extinct

2) Species 2 goes extinct

3) Both species coexist

Front 6

Lotka-Voltera Model of Competition:

Explain when equilibrium occurs.

Back 6

Coexistence occurs when both species reach equilibrium densities where:

dN1/dt = dN2/dt = 0

i.e. population is not growing

Front 7

Lotka-Voltera Model of Competition:

What are the two times where coexistence occurs?

Explain what this means about when coexistence is expected.

Back 7

(K₂ / β) > K₁

and

(K₁ / α) > K₂

-------------------------------------------------

1) Coexistence is predicted if the competition coefficients (α and β) are small (less than 1)

2) Coexistence expected if intraspecific competition is a stronger force than interspecific competition..

Front 8

Define:

Resource partitioning

Back 8

Species specialize on different resources.

Front 9

What was the example organism for:

Resource partitioning

Back 9

The anolis lizard communities in the Dominican Republic

The were able to coexist because they ate different insects.

Front 10

True or False:

It's possible for competition to occur between distantly related taxa.

Back 10

True.

Front 11

Describe the Brown and Davidson experiment (1977), and what it showed.

Back 11

This experiment shows how it's possible for competition to occur between distantly related taxa.

Experiment:
In a desert granivore community:
- Ant removal increased rodent density by 20%

- Rodent removal increased any colony numbers by 71%

- Ant and rodent removal increased seed densities in soil by 5x.

Front 12

Competition reduces...

Back 12

...individual fitness.

Front 13

Natural selection will favor traits that...

Back 13

...*decrease* competition and *increase* fitness

Front 14

Define:

Character displacement

Back 14

Competing species display greater difference when they co-occur than in areas where they occur separately.

[12.22]

Front 15

What was the example of character displacement given?

Back 15

Darwin's finches (Geospiza)

1) Seed eating birds on the Galapagos Islands

2) Beak size patterns suggest character displacement.

On islands where different species of bird co-occurred, beak size varied

On islands where a species was alone, beak size was relatively constant.