1. The effect of interspecific competition on population growth
Moretz
Biology, 2016

2. Review Ecological Relationships Predator/Prey Producer/Consumer
Symbiosis
Competition

3. Ecological Relationships

4. Ecological Relationships

5. Ecological Relationships

6. Niche & Competition Niche
The role an organism plays in an ecosystem and the resources it uses.

7. Competition
Struggle over scarce resources

8. Competition Struggle over scarce resources
Intraspecific competition = within the same species

9. Competition Struggle over scarce resources
Interspecific competition = between organisms of different species

10. Competition Struggle over scarce resources Food Water Shelter Mates
Light

11. The Struggle for Existence
G.F. Gause, 1934
Theory of Competitive Exclusion: describes what will happen to the populations of different species when they have nearly identical niches.

12. The Struggle for Existence
Predicted that when two species occupied the same niche, the population with the greater growth rate will be successful and the other will be eliminated.
No 2 species can occupy the same niche.

13. Experimental Evidence
Design and implement an experiment that supports or refutes Gause’s claim (paramecium focus).

14. Experimental Evidence
Design and implement an experiment that supports or refutes Gause’s claim (plant focus).

15. Background Info. Paramecium Unicellular Eukaryote (nucleus)
Aquatic, freshwater
Use cilia to move
Consume algae, bacteria, decomposing plant material.
Eaten by other protists.
Reproduces asexually or sexually, 2-3 times per day.

16. Background Info. Paramecium aurelia Paramecium caudata

17. Sampling Technique (paramecium)
Culture: 4 mL of Paramecium in 128 mL of hay medium in 250 mL flask.
Sampling:
Agitate culture
Pipette 1 mL to sample culture.
Release 2-3 drops back into culture.
Quickly place next drop on slide and cover with cover slip.
Repeat 5 times.
Place remaining sample back into culture.
Count all organisms in each drop.
There are 20 drops per 1mL. One drop = .05mL.
Calculate the average number of organisms per 1 mL.
From Lab 4 & 5. Protist Population Dynamics
Developed from Glase and Zimmerman (1991)

18. Background Info. Raphanus sativus Poa pratensis

19. Sampling Technique (plants)
Plant types: raddish and grass
100% grass
80% grass, 20% raddish
Planter cups filled with soil to top rim.
40% grass, 60% raddish
60% grass, 40% raddish
Add a total of 20 seeds per plant
20% grass, 80% raddish
100% raddish
Ratios:

20. Repeating Gause’s Competitive Exclusion Experiment
Design and implement an experiment that supports or refutes Gause’s claim.
Paramecium focus
Plant focus

21. Lab Timeline
Formulate a hypothesis regarding the effect of interspecific competition on population growth of Paramecium. (Tues.)
Draw a sketch of the experimental procedure. (Tues.)
Complete the experimental design diagram. (Tues.)
Create a data table. (Tues.)
Take initial observations of paramecium. (Wed.)
Establish paramecium cultures. (Wed.)
Collect data. (Oct. 5 – Oct. 20)
Analyze data. (Oct. 21)