The Predator and Prey Relationship

Competitive Relationships

And Predator and Prey

Competition

• Competition is when two or more parties strive for a goal that cannot be shared. One gains and the others lose.

Competition within a Population

• Competition is often seen between members of the same population, even siblings. 

• Many organisms produce far more offspring than can survive in their environment.

• These maple saplings will all compete for the same sunlight, water and space.

Wolf Competition

• Wolves compete for rank within their pack

• Competition also happens between packs for territory, for example.

Stressful Conditions

• Sometimes competition among members of the same population occurs only during stressful conditions.

• If the population is small, plenty of resources are available for each rabbit.

• If the population increases competition occurs for all resources.

Poll

Do you understand how competition works in ecosystems?

• Yes sir!

• Mostly

• A lil

• Not at all

Questions?

Competition between populations

• Competition also happens between members of different species.

• In the desert, many plants compete for water.

• Sagebrush and creosote bushes make chemicals that poison any plant growing too close to them.

Predator and Prey

• Any animal that eats another animal is a predator.

• An animal or organism taht is eaten by another is know as prey.

• Plants are not known as prey, so herbivores are never known as predators.

Competition Among Predators

• In any given ecosystem, there are often many predators competing for a limited amount of prey.

• If there is a small amout of prey, this can lead to agression between the different predators.

• Of course, the opposite is also true.

Predator-Prey Cycles

• There is a close relationship between the population of predators and prey.

• When the prey population increases, the predator population will increase in the coming years.

• The increase in predators will cause the prey population to go down.

Predator-Prey Cycles

• The repeated pattern of change in population is calles a predator-prey cycle.

• Notice at the end of the chart, how the moose population rises as the wolf population declines.

Competition in a Community

• Resources in an ecosystem might be limited, and organisms in that community might be forced to compete with each other.

•  This includes predators competing for prey or herbivores competing for plants. 

Multiple Select

What other factors, besides the moose population, could have affected the small rises in the wolf population at the beginning of the graph?

• A rise in the rabbit population

• Laws against hunting wolves.

• a decrease in the population of small rodents.

• Laws encouraging the hunting of wolves.

Multiple Choice

How do foxes affect the bison?

• Foxes are predators, and bison are their prey.

• Foxes keep the number of prairie dogs down.

• Foxes keep the number of wolves down.

• Foxes don't affect the bison.

Multiple Select

Which of the following involves two organisms competing for the same resource?

• Foxes and bison compete for prairie dogs.

• Wolves and foxes compete for prairie dogs.

• Foxes and wolves compete for prairie grasses.

• Prairie dogs and bison compete for prairie grasses.

Multiple Select

Name a predator-prey relationship in this community.

• foxes, wolves

• bison, prairie grasses

• prairie dogs, bison

• wolves, prairie dogs

Do Predators Benefit Prey?

• Usually a predator is harmful to prey.

• But, predators keep the prey population small enough to have ample food available.

• When enough food is available, the prey population is healthier.

Multiple Select

Imagine a population of rabbits in the woods. What resources do they need?

• grasses

• space

• shelter

• toys

Multiple Select

Imagine a population of rabbits in the woods. Who are they competing with for resources?

• One another

• grasshoppers

• white tailed deer

• groundhogs

Multiple Select

Imagine a population of rabbits in the woods. What predators are they hunted by?

• chipmunks

• wolves

• hawks

• deer

Multiple Choice

Wolves and hawks both eat rabbits. What type of competition is this?

• Competition within a species.

• Competition between species

• Stress competition.