Chapter 2 Principles of Ecology
I. Organisms and their environments
Main Idea: The interactions of biotic & abiotic factors in a community or ecosystem form a tight web
A. What is Ecology?• 1. The scientific study of interactions
among organisms and their environment.
*Ecology comes from the greek word oikos meaning house and ology-to study*
2. Reveals interdependence3. Scientist who study it = Ecologist
B. Aspects of Ecological Study
1. -the portion of earth that supports life
-scientist study
the diversity
of organisms
& factors
that effect
them
2. Abiotic Factors
• a. air currents
• b. temperature
• c. moisture
• d. light
• e. soil
• f. rainfall
• g. available nutrients
3. Biotic Factors• a. plants
• b. animals
• c. bacteria
• d. fungi
• e. protists
C. Levels of Organization
• 1. Ecologist study interactions among organisms at several different levels.
• Know list on page 36
2. Levels include:
• a. Organism- one individual living thing
• b. Population- group of one species that interbreed and live in the same place.
• c. Biological Community- collection of interacting populations that occupy the same geographic area
d. Ecosystems- interactions among populations in a community and the physical surroundings.
Mobile, AL
D. Organisms in Ecosystems
1. Habitat-place an organism lives.
2. Niche-role and position a species has in its environment.
3. Living Relationships
• a. Symbiosis- Living together
b. Symbiotic relationships include:
• (1) Commensalism-one species benefits and the other species is unaffected.
(2) Mutualism- both species benefit.
Termites and intestinal flagellates: Sea anemone and the clown fish
(3) Parasitism- one organism derives benefit at the expense of another.
II. Flow of energy in an Ecosystem
Main Idea: Autotrophs capture energy, making it available for all members of a food web
A. How organisms obtain energy• 1. Autotrophs-make their own nutrients
from an energy source.
• 2. Heterotrophs- cannot make their own energy-they must feed on other organisms.
3. Heterotrophs include:
• a. herbivores-plant eaters
b. carnivores-kill and eat meat
c. Scavengers-eat already dead animals (don’t kill)
d. Omnivores- eat meat and plants
e. Decomposers- breakdown complex molecules. (detrivores)
B. Models of Energy Flow
1. Food Chain
• a. Shows how matter and energy move
through an ecosystem.
• b. Simple-shows one possible route.
• c. Algae fish heron
• d. Consist of 3-5 steps.
2. Trophic Levels• a. Trophic levels = feeding step
• b. Feeding = energy transfer
3. Food Webs
A model representing the many interconnected food chains and pathways in which energy can flow.
4. Ecological Pyramids
• a. Energy Pyramid- shows how
energy flows through an ecosystem.
b. Numbers pyramid
*number of individuals at each level decreases b/c there is less energy to support them
c. Biomass Pyramid• Expresses weight of living material at each
trophic level
III. Cycles in the Biosphere• Biogeochemical Cycles- exchange of matter
through the biosphere
• - Matter, in the form of nutrients moves through the organisms at each trophic level.
• - Matter cannot be replenished by sunlight.
• - Matter must be constantly recycled.
-Nutrient Cycles include:
B. Carbon/Oxygen Cycle
c. Nitrogen Cycle
d. Phosphorus Cycle