Competition Flashcards
What is the main idea of Darwin’s statement from 1859?
There must be a struggle for existence due to more individuals being produced than can survive.
Who conducted the well-known work ‘The Struggle for Existence’?
G. F. Gause, a Russian microbiologist.
What is Gause’s principle?
If both competitors are limited by the same resource, they cannot coexist indefinitely.
What does the Competitive Exclusion Principle state?
A stable equilibrium between two populations cannot be achieved if they share similar ecological niches.
Give an example of species competition mentioned in the text.
The native Hawaiian short-eared owl (pueo) and the introduced barn owl.
What organisms did Gause experiment with?
Paramecium caudatum and P. aurelia.
What was the outcome of Gause’s experiment with P. caudatum and P. aurelia?
P. caudatum perished with a fixed amount of bacteria present.
In Gause’s experiments, why did P. caudatum coexist with P. bursaria?
Because P. bursaria only fed at the bottom of the test tube.
What are the four possible outcomes of interspecific competition between two species?
- Species 1 wins
- Species 2 wins
- Competition can go either way
- Coexistence
What does the Lotka-Volterra model of interspecific competition extend?
It extends the logistic equation to include effects of a second species on K.
What do the competitive coefficients α and β represent in the Lotka-Volterra model?
- α: competitive impact per individual of species 2 on species 1
- β: impact of species 1 on species 2
What happens when α or β is less than 1?
Intraspecific competition is greater than interspecific competition.
What is the significance of zero population growth isoclines in competition?
They are used to examine outcomes of competition.
What did Tilman study in his competition studies?
Two diatom species requiring silica.
What was the outcome of Tilman’s experiment with Synedra and Asterionella?
Synedra reduced silicon availability, excluding Asterionella.
What are the assumptions of competitive exclusion?
- Competitors have exactly the same resource requirements
- Environmental conditions remain constant
Why are the assumptions of competitive exclusion problematic?
They do not account for variability in resource requirements and environmental conditions.
What does Gause’s principle suggest about co-existing species?
There should be selective pressure on them to ‘learn to share’ resources.
What is resource partitioning?
The process where co-existing species reduce interspecific competition by sharing resources.
How do plants partition soil resources?
By varying root morphology.
Give an example of three species that partition resources in prairie soil.
- Bristly foxtail: shallow roots
- Indian mallow: intermediate roots
- Smartweed: deep taproot
What is usually observed along an environmental gradient?
Realized niches.
Why is competition considered complex?
It rarely involves simple two-way interactions between two species limited by a single resource.
What types of species interactions are mentioned regarding invasive species?
- Competition for prey: mongoose, barn owl, and cats
- Nest predation: mongoose, barn owl, cats, rats, and pigs
What is a significant impact of invasive species on native species?
Several species compete and predate on the native pueo.
