Ecology
Definition: The study of the relationships among living organisms and the interactions the organisms have with
their environment.
Focus – interactions, interconnectedness, interdependance, inter-related, i.e., a web
A disturbance in one area actually has a broad impact on the entire ecosystem!
 The Butterfly Effect
Ecological models - modeling
A visual, verbal or mathematical method
to explain complex interactions
Terms:
Habitat
 the place where an organism lives
Niche
 the role and position a species has in its environment
 how it lives, gets food, reproduces, gets shelter
Biotic factors
 living component of ecosystem
Abiotic factors
 non-living component of ecosystem
 the environment
Levels of Organization
Biosphere
 layer of life surrounding the earth
Ecosystem

biotic and abiotic factors
Biomes
 largest ecosystems
Community
 Biotic factors
Population
 all organisms of one individual species in a particular place at a particular time
Organism
 an individual organism
Species Interactions

Symbiotic Relationships (Symbiosis)
Predation – Predator-Prey Interactions
Mimicry
Cryptic Coloration – Camouflage
Warning Coloration
Plant-Herbivore Interactions, e.g., secondary compounds
Parasitism – Ecto, Endo
Competition
Mutualism
Commensalism
Energy
Producers – autotrophs
photosynthesis, chemosynthesis
Consumers - heterotrophs
Herbivores
Carnivores
Omnivores
Insectivores
Scavengers
Detritivores
Decomposers, saprophytes
Energy Flow
Trophic Levels
1st trophic level – producers
2nd trophic level – herbivores
3rd trophic level – 1st order carnivores
4th trophic level – 2nd order carnivores
5th trophic level – scavengers and detritivores
Food Chain – single pathway of feeding relationships
Food Web – complex interactions of many food chains
Energy Flow
Ecological Pyramids
Pyramid of Numbers
Pyramid of Biomass
Pyramid of Energy
Quantity – 10% rule – 10% of energy at one trophic level is transferred to the next trophic level
Range: 20% to 1%, e.g., Isle Royale: moose  wolf, 1.3%
Short food chains/pyramids are more efficient!
Ecosystem Recycling – Nutrient Cycling
Biogeochemical Cycles
The Water Cycle
Ground water, transpiration
The Carbon Cycle
The Nitrogen Cycle
Nitrogen fixation
- nitrogen-fixing bacteria
Recycling nitrogen
Ammonification
Nitrification
Denitrification
The Phosphorus Cycle