Chapter 13: Principles of Ecology
13.1 KEY CONCEPT
Ecology is the study of the relationships among
organisms and their environment.
Chapter 13: Principles of Ecology
Ecologists study environments at different levels of
organization.
• Ecology is the study of the interactions among living
things, and between living things and their surroundings.
Example: Salmon
•Over 140 species
eat salmon
•Important for
economy
•Important for
health of river
systems
Chapter 13: Principles of Ecology
• An organism is an individual living
thing, such as an alligator.
Organism
Organism
Chapter 13: Principles of Ecology
• A population is a group of the same
species that lives in one area.
Population
Population
Organism
Organism
Chapter 13: Principles of Ecology
• A community is a group of different
species that live together in one area.
Community
Community
Population
Population
Organism
Organism
Chapter 13: Principles of Ecology
• An ecosystem includes all of the
organisms as well as the climate, soil,
water, rocks and other nonliving things
in a given area.
Ecosystem
Ecosystem
Community
Community
Population
Population
Organism
Organism
Chapter 13: Principles of Ecology
• A biome is a major regional or global
community of organisms characterized
by the climate conditions and plant
communities that thrive there.
Biome
Ecosystem
Ecosystem
Community
Community
Population
Population
Organism
Organism
Chapter 13: Principles of Ecology
Concept Check: Organism, Population, Community,
Ecosystem, Biome
•
•
•
•
•
Desert
Cricket
River
Barrel of monkeys
Decayed Log
In your notes, give an example of each of the
five levels. They should build on each other!
Chapter 13: Principles of Ecology
13.2 KEY CONCEPT
Every ecosystem includes both living and nonliving
factors.
Chapter 13: Principles of Ecology
Create 2 columns in your notes, one labeled Biotic, the
other Abiotic. Classify each thing below.
•
•
•
•
•
•
•
•
•
•
Water
Fish
Paper
Glass
Aluminum
Wooden ruler
Sand
Clouds
Snail
Air
•
•
•
•
•
•
•
•
•
•
Steak
Salad
Bread
Hair
Finger nails
Pipe
Cotton fabric
Gold
Plastic
Grapes
Chapter 13: Principles of Ecology
An ecosystem includes both biotic and abiotic factors.
• Biotic factors are living things.
– plants
– animals
– fungi
– bacteria
plants
Chapter 13: Principles of Ecology
• Abiotic factors are nonliving things.
– moisture
– temperature
– wind
– sunlight
– soil
What is the first level
of organization that
includes abiotic
factors?
a. Populations
b. Biome
c. Ecosystem
d. Community
sunlight
moisture
Chapter 13: Principles of Ecology
Changing one factor in an ecosystem can affect many
other factors.
• Biodiversity is the assortment, or variety, of living things in
an ecosystem.
• Rain forests have more biodiversity than other locations in
the world, but are threatened by human activities.
– Only 7% of the world’s surface
– 50% of the world’s plant and animal species
Chapter 13: Principles of Ecology
• A keystone species is a species that has an unusually large
effect on its ecosystem.
keystone
Chapter 13: Principles of Ecology
• Keystone species form and maintain a complex web of life.
– Examples: Beaver, Salmon
creation of
wetland
ecosystem
increased waterfowl
Population
keystone species
increased
fish
population
nesting
sites for
birds
Chapter 13: Principles of Ecology
13.3 KEY CONCEPT
Life in an ecosystem requires a source of energy.
Chapter 13: Principles of Ecology
Producers provide energy for other organisms in an
ecosystem.
• Producers - energy from non-living resources.
• Producers are also called autotrophs…why?
• Basis for EVERY ecosystem!
Dark green =
heavy
forestation, a lot
of producers
Yellow = very
few producers
Chapter 13: Principles of Ecology
Producers provide energy for other organisms in an
ecosystem.
• Consumers - energy by eating
• Consumers are also called heterotrophs…why?
Chapter 13: Principles of Ecology
Almost all producers obtain energy from sunlight.
• Photosynthesis in most producers uses sunlight as an
energy source.
– How do we, as humans, get the energy from the sun?
• Chemosynthesis in prokaryote producers uses chemicals
as an energy source.
carbon dioxide + water +
hydrogen sulfide + oxygen
sugar + sulfuric acid
Chapter 13: Principles of Ecology
13.4 KEY CONCEPT
Food chains and food webs model the flow of energy
in an ecosystem.
Chapter 13: Principles of Ecology
Choose any three organisms and use them to fill in the
food chain below
Producer
Herbivore/Omnivore
Grass
Cow
Plankton
Whale
Carnivore/Omnivore
Human
Shark
Chapter 13: Principles of Ecology
A food chain is a model that shows a sequence of feeding
relationships.
• A food chain links species by their feeding relationships.
• A food chain follows the connection between one producer
and a single chain of consumers within an ecosystem.
• REMEMBER…Arrows show the direction the ENERGY
moves!!
GRAMA GRASS
DESERT COTTONTAIL
HARRIS’S HAWK
Chapter 13: Principles of Ecology
• Consumers are not all alike.
– Herbivores eat only plants.
– Carnivores eat only animals.
– Omnivores eat both plants and animals.
– Detritivores eat dead organic matter.
– Decomposers are detritivores that break down organic
matter into simpler compounds.
carnivore
decomposer
Chapter 13: Principles of Ecology
• Specialists are consumers that primarily eat one specific
organism or a very small number of organisms.
• Generalists are consumers that have a varying diet. Do not
have a single source of food.
Chapter 13: Principles of Ecology
• Trophic levels are the nourishment levels in a food chain.
– Primary consumers are herbivores that eat producers.
– Secondary consumers are carnivores that eat
herbivores.
– Tertiary consumers are carnivores that eat secondary
consumers.
– Omnivores, such as humans that eat both plants and
animals, may be listed at different trophic levels in
different food chains.
Chapter 13: Principles of Ecology
A food web shows a complex network of feeding
relationships.
• An organism may have multiple feeding relationships in an
ecosystem.
• A food web emphasizes complicated feeding relationships
and energy flow in an ecosystem.