Ecology of Organisms

Biotic and Abiotic Factors

• The living components of the environment are called biotic factors.

• The non-living components of an environment are called abiotic factors.

The changing environment

• Abiotic factors are not constant

• Temperature varies

• The photoperiod varies with seasons

Response to a Changing Environment • Organisms are able to survive within a

wide range of environmental conditions

• A graph of performance vs. values of environmental variables is called a Tolerance Curve

Acclimation

• Some organisms can adjust their tolerance to abiotic factors through a process called acclimation.

Control of internal conditions

• Conformers are organisms that cannot control their internal conditions. Ex jellyfish, reptiles.

• Regulators control internal body conditions and keep their bodies in the optimal range over a wide variety of environmental conditions.

Escape from Unsuitable Conditions

• Some species can escape from unsuitable conditions temporarily, there are also others who remain in a state of reduced activity called dormancy

• Another way a species can cope with an unsuitable environment is to leave or migrate to more hospitable areas.

Resources• Whether a species can survive in an area

depends on the suitability of environmental conditions as well as availability of resources.

The Niche (nich)

• The niche is a species way of life.

• A species’ fundamental niche is the range of conditions that they could potentially tolerate.

• A realized niche is the range of resources that a species actually uses.

Niche Differences

• Generalists are species with broad niches.– Opossum – Raccoon

• Specialists are species with narrow niches.– Koala

p. 3721. List three abiotic factors that can affect an

organism

2. What does a tolerance curve indicate curve indicate about an organism

3. What is migration? Give an example of migration.

4. How is an organism’s niche different from it’s habitat.

5. List two factors that might cause an organism to restrict its use of a resource.

6. Explain why two different species do not occupy exactly the same niche.