Chapter 2: Principles of
Ecology
Ecology
The study of the interactions between organisms and their
environment
Includes both Biotic (living) and abiotic (nonliving) factors
Abiotic factors might include:
Temperature
Water availability/quality
Terrain (mountains, flat land, etc.)
Soil chemistry
Etc.
The biosphere
The portion of Earth that contains life
Stretches from the high atmosphere to the deepest ocean
“Skin of an apple”
Levels of Ecological organization
Organism=1
Population=group of same species in same area who interbreed
Community=interacting populations
Ecosystem=communities and abiotic factors
Biosphere=portion of planet that supports life
So very important!
Within populations and
communities, there is competition
for limited resources (i.e. food,
water, shelter, etc.)
2 types of ecosystems
Terrestrial= on, under, or near land
Aquatic=in water
These ecosystems do occasionally overlap (pelicans, frogs, etc) but are in
their own category and are influenced by different things.
Habitat vs. Niche
An organism’s habitat is simply where it lives
An organism’s niche is the role or position of the organism in the habitat
Symbiosis
Sym=together (think “symmetry”)
Bio=life
Means “living together”
3 types, defined by how they impact one another
Mutualism (+/+)
Both organisms are benefitted
Commensalism (+/0)
One organisms gets a benefit, the other is unaffected
Parasitism (+/-)
One organism is benefitted, the other is harmed
Usually does not kill host, because it relies on it for survival
Nutrition and Energy Flow
Terms:
Autotroph: “Auto”=Self “troph”=nourishment
A.k.a. Producer
Organism that makes its own energy (ex. Plants and some bacteria)
Heterotroph: “Hetero”=other
A.k.a. consumers
Get energy from consuming other living matter (ex. Animals, fungi)
Decomposers
Break down dead/dying matter into nutritional materials (ex. Fungi)
Types of Heterotrophs
Herbivore-only eats plants
Carnivore=“only” eats other animals
Omnivore=eats plants and animals
Scavengers=only eat dead organisms
How energy moves through an
ecosystem
Diagrams
Food chain-simple diagram showing where energy goes
Producer (Autotroph)→Primary Consumer (Herbivore)→Secondary consumer
(carnivore)→Decomposer
NOTE: Arrows show where the ENERGY is going, not what is eating what
Food web
More complex than food chain
Shows all possible feeding relationships
More realistic, but seldom perfect
Trophic Levels
Feeding step in energy chain
Begin with autotrophs
1st order heterotroph (herbivore)
2nd order heterotroph (carnivore)
3rd order heterotroph (carnivore or scavenger
Decomposer (everything ends with decomposers!)
Energy Pyramids
Model to show how much energy is available at each level
As energy moves on, only a small portion (10%) is available at the next stage
The rest is lost to the environment as heat (metabolism) while with the organism
Biomass-mass of living matter at each level
Cycles in Nature
1.
Water cycle
2.
Carbon cycle
3.
Nitrogen cycle
4.
Phosphorus cycle
With a partner, draw each of the cycles using your own design (do not copy the book,
but use it as a reference)
One person will dictate what to draw.
The second person will draw.
Switch roles for each one.
Both should be able to answer questions about the pictures.
We’ll vote to see which ones should be posted in the room.