Principles of Ecology
Chapters 3, 4, 5, & 6
A. What is Ecology?
• Ecology is the study of interactions between
organisms and their environment.
B. Biotic vs. Abiotic Factors
1. Biosphere – portion of the Earth supporting life
2. Biotic factors
a. All organisms inhabiting the environment
b. Each organism adapts to its part of the biosphere
3. Abiotic factors
a. Nonliving parts of the environment
b. Can determine which species will survive
examples: rainfall, temperature, light, soil
Abiotic Factors
Biotic Factors
ECOSYSTEM
C. Levels of Biological Organization
1. Populations
a. A group of organisms of the same species living
together
b. Must compete for resources
2. Community
a. Several populations that interact
b. Changes in one population will cause changes in the
others
3. Ecosystem
a. Interactions between populations and their
surroundings
b. 2 main types:
1. Terrestrial – land
2. Aquatic – fresh or salt water
Levels of Biological Organization
D. Niche vs. Habitat
1. Niche
•
The role an organism plays in the environment
(Its “job” in the community)
2. Habitat
• Place where an organism lives
Three
Species of
Warblers and
their niches
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Bay-Breasted Warbler
Feeds in the middle
part of the tree
Spruce tree
Yellow-Rumped Warbler
Feeds in the lower part of the tree and
at the bases of the middle branches
E. Types of Feeding Relationships
1. Autotrophs
a. Self-feeders, produce their own
food
b. Example: plants, algae
2. Heterotrophs
a. Depend on other organisms for
food
b. Herbivore – eats only plants
c. Carnivore – eats only meat
d. Omnivore – eats both
3. Decomposers
a. Break down and absorb nutrients
from dead organisms
b. Example: mushrooms, bacteria
4. Commensalism
bacteria
a. Relationship in which one species benefits and the
other is not affected
b. Example: remoras that live on/around a shark’s
mouth
Remora
on a Ray
tickbirds
5. Mutualism
a. Both species benefit
b. Example: tickbirds eat
parasites off of a rhino
oxpeckers
6. Parasitism
a. One organism benefits
and the other is harmed
b. Example: tapeworm
living inside a person’s
intestine
F. Compare Food Chains and Food Webs
1. Food Chains
a. Model showing movement of
energy through the ecosystem
b. Uses arrows to show “what
eats what”
2. Food Web
a. More complicated than a food
chain
b. Shows more than one food
source for each organism
c. More realistic view of energy
transfer
Food Chain
Grass  Cow  Human
Food Web