Habitats and Niches`

Habitats

o Organisms require certain things in order to survive such as food, light, shelter, and water.

o An organism’s habitat is the area where it can survive because it has these requirements in large enough amounts to support populations of the organism.o A habitat is the environment where an

organism lives.

Niche

Pronounced “N-itch” A niche is an organism’s way of life.

In includes the habitat, the food it eats, and all other organisms it interacts with. Another way to think about it is the

organism’s job. Often a specific niche leads to evolution

of similar traits.

Niche

Fundamental niche All resources that could be used in absence of

competition.

Realized Niche

Realized nicheResources actually used in the presence of competitors.

Niche Overlap

o When the niche of two species overlaps and competition is apparent.

Competition is Expensive!

o Organisms try to avoid it by getting M.A.D., they would prefer to:o Moveo Adapto Die

Resource partitioning

o It helps competing species share a resource.

o Occurs when species require different parts of the same resource.

Competition and niches Competitive exclusion

o If two species, with the same niche, coexist in the same ecosystem, then one will be excluded from the community due to intense competition.

The Grey Squirrel The Red Squirrel The Red Squirrel is native to Britain, but its population has declined due to competitive exclusion, disease and the disappearance of hazel coppices and mature conifer forests in lowland Britain.The Grey Squirrel - was introduced to Britain in about 30 sites between 1876 and 1929. It has easily adapted to parks and gardens replacing the red squirrel.

Niches and resources

Resource partitioning avoids competition;

Realized niches divide resources (insects) among several species woodpeckers,

nuthatches, & creepers. Each species evolved &

adapted to specialized diet.

Galapagos Finches -from Grant 1986

But… While there are many

habitats on the Earth, not all organisms can live in one habitat. Each habitat has a limiting factor. The limiting factor is one or

more resources that controls the amount of organisms in the habitat.

Carrying capacity

Since every habitat has a limited number of resources, scientists are able to establish a carrying capacity for each area. The carrying capacity is the

maximum number of organisms that can survive over a long period of time in one area.

Because there are limits like this to any habitat, organisms begin to compete for resources.

The End!