Chapter 16 - Competition Flashcards
What is intraspecific competition?
Competition among individuals of the same species.
What is interspecific competition?
Competition among individuals of different species.
What are common resources of plants?
Sunlight, soil nutrients, water.
What are resources of animals?
Food, water space.
What is not considered a resource?
An ecological factor, such as temperature or pH, that cannot be consumed or used.
What is a resource?
Anything an organism consumes or uses that causes an increase in the growth rate of a population when it becomes more available.
What are renewable resources? Provide examples.
Resources that are constantly regenerated; seeds, sunlight.
What are nonrenewable resources? Give an example.
Resources that are not regenerated; space.
Where can renewable resources originate?
From inside or outside the ecosystem.
How does competition impact resources that come from outside the ecosystem?
Can reduce their abundance but cannot affect the rate of resource supply.
How does competition impact resources that arise from inside the ecosystem?
Can affect supply and demand.
What is Liebig’s law of the minimum?
A population increases until the supply of the most limiting resource prevents it from increasing further.
When two species compete for a single limiting resource, which species persists?
The one that can drive down the abundance to the lowest level.
What does Liebig’s law assume?
If a given resource limits the growth of individuals and populations, increasing the availability of other resources will not improve this growth.
What is the competitive exclusion principle?
Two species cannot coexist indefinitely when they are both limited by the same resource.
What observations were the basis for the competitive exclusion principle?
Generally, one species is better at obtaining the resource or is better able to survive when the resource is scarce.
Why do closely related species living in the same region often exist in different habitats?
Over the course of evolution, developed competitive advantages in their own environment.
To add a second species to the logistic growth model, what two pieces of information do we need?
- # of individuals of second species.
- How much each individual of second species affects carrying capacity of the first species.
What are competition coefficients?
Variables that convert between the number of individuals of one species and the number of individuals of another species.
Under what two conditions does the dual species logistic growth model reach equilibrium?
- When N = 0
- When carrying capacity is reached.
Explain the basics of what each figure is representing (a and b)
Figure a: Equilibrium isocline for species 1 (green line) representing the combinations of species’ 1 population size (N1) and species 2 population size (N2) that make population 1 experience zero growth.
Figure b: Equilibrium isocline for species 2 (purple line) representing the combinations of species’ 1 population size (N1) and species 2 population size (N2) that make population 2 experience zero growth.
What is the abundance of species 1 when species 2 has an abundance of 0? What is the abundance of species 2 when species 1 has an abundance of zero? What do these values represent?
When species 2 has an abundance of 0, species 1 has an abundance of K1, its carrying capacity.
When species 1 has an abundance of 0, species 2 has an abundance of K2, its carrying capacity.
What do the arrows in these figures represent?
Indicate how each population either increases or decreases as it moves away from the equilibrium line.
What is a zero population growth isocline?
Population sizes at which a population experiences zero growth.
Do growth rates effect the position of an isocline?
No, growth rates determine how quickly a population will meet equilibrium but not the location of equilibrium.
How can we determine if one of two species will win the competitive interaction or if the two will coexist?
Overlap their individual zero growth population isoclines.
What is depicted in this figure? What will happen to each population?
Isocline for species 1 is further than species 2. Species 1 will increase to carrying capacity K1 and species 2 will go extinct.
What is depicted in this figure? What will happen to each population?
Isocline for species 2 is further than species 1. Species 2 will increase to K2 and species 1 will go extinct.
What is depicted in this figure? What will happen to each population?
Isoclines cross and carrying capacities are on outermost points of the axes. Winner depends on initial population size of each species.
What is depicted in this figure? What will happen to each population?
Isoclines cross and carrying capacities are on innermost points of the axes. The species will coexist.
When is coexistence between species most likely?
When interspecific competition is weaker than intraspecific competition.
When competing for two different resources, when does one species have a competitive advantage?
When one species is better able to sustain itself with low levels of both resources.
When competing for two different resources, when coexistence between two species occur?
When one species can better sustain itself at low levels of one resource and the other species can better sustain itself at low levels of the other resource.
What is a common trade-off related to competition?
Trade-off between competitive ability and the ability to tolerate a challenging abiotic factor.
Which plants are most susceptible to herbivores? Which animals are most susceptible to predators? What can this be attributed to?
The most competitive plants and animals. Trade-off between resistance to predators and competitive ability.
What is exploitative competition?
Competition in which individuals consume and drive down the abundance of a resource to a point that other individuals cannot exist.
What is interference competition?
When competitors do not immediately consume resources but defend them.
Is exploitative competition considered direct or indirect competition?
Indirect
What is an effective form of interference competition that occurs between animal species?
Aggressive interactions
What is allelopathy?
A type of interference that occurs when organisms use chemicals to harm their competitors.
What is apparent competition?
When two species have a negative effect on each other through an enemy, including a predator, parasite or herbivore.
