Lecture 20 Flashcards
(28 cards)
For tiny organisms what’s the y axis?
Biomass (relative volume)
Competitive exclusion
Two species competing for the same limited resources cannot coexist indefinitely. Eventually, one species will outcompete and exclude the other, leading to its local extinction or forcing it to adapt by occupying a different niche.
Both species reached K in _______ of interspecific comptition
Absence
How impacts a half- resource medium
Lower K
Which competition predominates when K is reached in absence of interspecific competition?
Intraespecific competition
Limited resources __________ competitive intensity
Increase in intra and interspecific competition
Gause noted that:
- Exclusion will often occur between closely related species
- Close relatives often have similar strategies to compete for
the same resource(s)
Gause proposed that:
No two species can coexist if they use the environment in precisely the same fashion
Competitive Exclusion Principle
Complete competitors cannot coexist
Paradox in ecology
Clearly competition is widespread
Lotka-Volterra competition model
Mathematical framework describing how two species compete for limited resources. It extends the logistic growth model by incorporating the effects of interspecific competition.
Why is important to use models to understand competition?
Models yield important predictions about the conditions promoting coexistence and exclusion of competitors.
What is α in competition coefficients?
Measure of the effect of species 2 on the growth rate of species 1. If α = 1, then individuals of the two species are interchangeable
What happens when α = 4?
Each individual of species 2 added depresses the growth of species 1 by the same amount as adding 4 individuals of species 1
What happens if If α > 1?
The per capita effect of interspecific competition is greater than the per capita effect of intraspecific competition
What happens if α < 1?
competition is more important
What happens if If α = 0?
There is no intercompetitive effect
Therefore, α is the per capita effect of _________ on the population growth of ________, measured relative to the effect of species 1.
species 2/species 1
T/F. α and β do not need to have the same values
True
T/F. Competition can be asymmetrical
True
State-space graphs
Used for plotting abundance of Species 1 on x-axis and the abundance of Species 2 on y-axis
What is represented in each point on graphs?
Combination of abundance of he two species
Zero-growth isocline (ZGI)
Expected equilibrium population size (dN/dt = 0) of one species
Which axis is N1?
X axis
