Principles of Ecology
Unit 2
Chapter 2
What is ecology?
• Ecology: study of
interactions that
take place
between
organisms and
their environment
Biosphere
• the portion of the
Earth that
supports living
things
• Ex: ocean, forest,
atmosphere.
Abiotic vs. Biotic factors
• Abiotic = nonliving parts of the environment
• Ex: light, air, temperature, soil
• Biotic = living parts of the environment
• Ex: bacteria, protist, fungus, plant, animal
Which is Biotic/Abiotic?
Levels of organization
• In biology, we begin
at the chemical level
which make up
cells…
• Which make
tissues…
• Organs…
• Systems…
• And finally, the
individual organism
Levels of organization from
smallest to largest in an
Ecosystem.
•
•
•
•
•
•
Organisms
Individual
Population
Community
Ecosystem
Biosphere
Levels of organization
• In Ecology, we begin with the
individual and move through the levels
to the planet, Earth
Individual
• made of cells, uses energy, reproduces,
responds, grows, and develops
Population
• group of organisms all of the same
species, which interbreed and live in the
same area at the same time
Community
• interacting populations in a certain area
at a certain time
Ecosystem
• interacting communities and abiotic
factors
Habitat vs. Niche
• Habitat: place where organism
lives
• Niche: role or position a
species has in its environment
End of What is Ecology Notes?
• Now let’s do some practice!!!
Energy Flow Through an
Ecosystem Notes Du (2)
Ecology and the flow of energy
and matter
• By the end of this portion of the notes
you should be able to describe how
matter and energy flow through trophic
levels using various models, including
food chains, food webs and ecological
pyramids
How organisms obtain energy
• Autotroph (producer): photosynthetic
or chemosynthetic, makes own food
• Heterotroph (consumer): “eat” other
organisms, cannot make own food
• Decomposer: breaks down dead or
decaying organisms, recycles matter
Autotroph
The sugar produced by autotrophs (through
photosynthesis) can then be used by heterotrophs
for energy
Heterotrophs - scavengers
• Scavengers: feed off of dead or
decaying living things but do not recycle
matter back into the ecosystem
Heterotrophs - herbivores
• consume only
vegetative matter
• mostly primary
consumers.
Heterotrophs - carnivores
• obtain energy
from eating other
consumers
• Secondary and
tertiary
consumers
Decomposers
•Bacteria and fungi break
down living matter and
help release nutrients.
•Decomposers are found at
every level of the food
chain.
•They are nature’s
recyclers.
Typical examples: fungus and bacteria
Autotrophs
Third-order
heterotrophs
First-order
heterotrophs
Second-order
heterotrophs
Decomposers
How Energy Flows
• From producer (autotroph) to consumer
(heterotroph)
AUTOTROPH
Water + CO2  Sugar + O2
HETEROTROPH
Sugar + O2  water + CO2
Food chain
• Series of steps in which
organisms transfer energy
by eating and being eaten
• The arrows show the
direction energy flows.
• Trophic levels: feeding
step
berries → mice → black bear
Food web
• shows
interactions
between
organisms
(all possible
routes)
Energy pyramid
• Shows how much
energy is available at
each trophic (energy)
level.
• Only 10% of the
available energy is
transferred up to the
next trophic level. The
rest is released as
heat
Pyramid of Energy
Heat
Heat
0.1% Consumers
1% Consumers
10%
Heat
Heat
Consumers
Pyramid of Numbers
• Each level
represents the
number of
organisms
consumed by the
level above it.
End of Lecture 2
Now lets
practice!!
Ecology Notes 3
Cycles
Two cycles in nature
• Carbon cycle
• Nitrogen cycle
CO2 in
Atmosphere
• Carbon Cycle
• driven by
photosynthesis &
respiration
CO2 in Ocean
• recycles carbon, a
primary component
of all organic
compounds
Carbon cycle
Nitrogen Cycle
• driven by decomposition of nitrifying bacteria and fungi
• atmospheric nitrogen must be converted to a usable
form (by plants)
N2 in Atmosphere
NH3
NO3 –
and NO2 –
Nitrogen cycle
Now let’s Practice
Time to Draw
some cycles.