Ecological Niches and Adaptation

• Ecological niche– Total way of life or functional role of a

species in an ecosystem.

• Habitat– Physical location of a species

Occupation

Address

Niches!!

Fundamental• The full range of

environmental conditions (biological and physical) under which an organism can exist

Realized• Narrower niche, a result of

pressure from, and interactions with, other organisms (e.g. superior competitors). They are mostly highly adapted to this one

According to the competitive exclusion principle, no two species can occupy the same niche in the same environment for a long time.

Generalist Species

• Can live in many different places

• Eat a variety of foods• Tolerate a wide range of

environmental conditions

• Makes them better adapters!

Homo sapiens

Human

Brown Rat

Procyon lotor

Racoon

CONSIDER THE COCKROACH• Eat anything! (algae,

dead insects, electrical cords, glue, paper, soap

• Live and breed anywhere (except polar regions)

• Can go months without food!

• Real good at hiding!• High reproductive rates!

Periplaneta americana

Cockroaches

Specialist Species

• Live in only one type of habitat

• Use only one or a few types of food

• Tolerate only a narrow range of environmental conditions

• Makes them more prone to extinction due to environmental change!

CONSIDER THE KOALA

• Only eats eucalyptus leaves

• What would happen if there were no more eucalyptus?

Patterns of Evolution

Gradualism

• Intermediate forms between extant (living) and extinct species

• Species evolve slowly, small changes add up

Punctuated equilibrium

• S J Gould• Periods of rapid

divergence alternating with periods of stability