Competition, Predation, and Symbiosis

Interactions within a community

Niche (nitch or neesh)The role of an organism in its habitateach species is specially adapted to its nicheIncludes:

Type of food it eatsHow it gets its foodWhat eats it (predators)Conditions it requires to survive and reproduce

Adaptations Organisms are adapted to survive in

their nicheAdaptations: Behaviors or physical

traits that allow organisms to live successfully in their environments

How do organisms become adapted to their niche? Natural

SelectionNatural Selection:

How a trait that makes an individual better suited to its environment may become common in the species

Survival of the fittest Individuals who are

best suited to their environment are more likely to survive and reproduce and pass their traits on

This makes their unique traits more common in the species

Results in adaptations

Remember…

An organism does NOT change its traits to suit the environment

Adaptations that can be changed through natural selection are GENETIC

CompetitionThe struggle between

organisms to survive as they try to use the same resources

If organisms try to occupy the same niche, they are competing.

One will either die out or moveOrganisms avoid competition

by occupying slightly different niches

Examples:Lions and Hyenas compete for the

same foodKudzo, and invasive plant in the south,

crowds out the native plants in a competition for space

Predation

When one organism kills another for food

Predator: The hunter

Prey: The huntedBoth are adapted to

help them survive

Predator Prey Interactions

Predators depend on prey to surviveWhen the population of prey is low, the

population of predators will go downWhen the prey population goes up,

predator populations tend to go up as wellIt is a cycle

Symbiosis a close relationship between two

species, where at least one of the species benefits

Three types: Mutualism, commensalism, parasitism

Mutualism

We’re friends! Both organisms benefit from the

relationship

CommensalismWe are sort of friends…Sometimes you

open my locker for me when it’s stuck because you are stronger then me…

One organism benefits, and the other is neither helped or harmed

parasitism

We are NOT friends. We are enemies.One organism lives on or in another

organism and causes harmSometime a parasite lives on its host

permanently (tapeworms), sometimes it is temporary (mosquitoes)

Common parasites

Other types of parasitesBrown headed

cowbird: lays its eggs in other birds nest to be raised by other birds at the expense of their own young.

Galls: Growths on plants caused by insects, fungi, bacteria, viruses. Very common.

Moose and Wolves of Isle Royale

Isle Royale is an island in Lake Superior

There is a population of moose and wolves that lives there.

The relationship between the moose and wolves has been studied since 1958. This is the longest predator prey study ever done.

•There are no permanent populations of people living on Isle Royale

•It is a national Park (hunting is illegal)

The Moose

The first moose arrived around 1900 by probably swimming the 15 miles from Canada

Wolves are its only predator Moose need to eat about 40 lbs of food/day

to surviveTicks, food supply, and weather all affect the

survival of moose (limiting factors)

The Wolf They arrived on Isle Royale around 1950 by

using an ice bridge from Canada (probably)Moose are its main food source (90%). They

will also eat snowshoe hare and beavers Beside starvation, they die due to fights with

other wolves over food (competition)

The Study

Other parts of the Isle Royale Community

Balsam FirRavensRed FoxRed SquirrelsMoose ticksBeaverSnowshoe hare