ECOLOGY

Ecological Organization

• Abiotic factor: Non-living things in an ecosystem that affect the life of the organism. – Sunlight– Air– Water– Temperature

• Biotic factor: All living things in an ecosystem. – Animals– Plants– Bacteria– Fungi

FACTORS AFFECTING POPULATION SIZE

Competition• When 2 or more species live in the

same area and eat the same organisms they are said to be in competition for those resources.

• Examples:– Cheetas and lions have the same

prey on the savannah in Africa– Grass and weeds in your yard

Coexistence/Cooperation

• When individuals of different species work together to meet their needs they are said to be coexisting or cooperating.

• There are several strategies that species use to cooperate:– Mutualism– Parasitism– Commensalism

Mutualism• An interspecies relationship in which

both species benefit from the interaction.

• Species 1 (+)• Species 2 (+)• Examples:

– A bee pollinating a flower– Fungus on plant roots– Clown fish and sea anemone

Parasitism• An interspecies relationship in which

one species benefits to the detriment (harm) of another.

• Host - Species 1 (-)• Parasite - Species 2 (+)• Examples:

– Fleas/ticks on a dog– Tape worm– Head lice

Commensalism• An interspecies relationship in which

one species benefits and the other is unaffected.

• Species 1 (+)• Species 2 (0)• Examples:

– Barnacles on a whale– Cattle egrets and livestock– Orchids on a tree

Energy Roles

Each organism fills a role of producer consumer or decomposer

PRODUCERSEnergy mostly come to Earth via sunlight and producers capture it to turn it into food molecules in a process called photosynthesis.

They are: plants, algaes and bacteria.

Producers are the source of all the food in an ecosystem

A producer can make its own food!

• Consumers cannot make their own food.

• Consumers obtain energy by feeding on (consuming) other organisms.

• They are classified by what they eat:– Herbivores– Carnivores– Omnivores

CONSUMERS

HerbivoresDo they eat “ Potatoes ” ? ? ?

?

PRIMARY CONSUMERS

• Also known as HERBIVORES • Ex: mice, deer, cows, and elephants• Herbivores eat ONLY PLANTS

• Are CARNIVORES or OMNIVORES• If the animal must be killed before it

is eaten, the secondary consumer is known as a predator.

SECONDARY CONSUMERS

• Feed on the bodies of dead organisms

SCAVENGERS

DECOMPOSERSBreak down wastes and dead organisms, and so complete the cycle by: ● returning nutrients to the soil &

water● returning carbon to the air & water

Food Chain

A food chain shows how each living thing gets food, and how nutrients and energy are passed from creature to creature. 

Food Webs

A food web consists of all the food chains in a single ecosystem.

Trophic Levels An organism’s position in the food

chain is often referred to as its trophic level.

Energy Pyramids• 90% of energy at each level is used

by the organism for its day to day existence.

• So only 10% transfers to the next level