Honors Biology 2010-2011
What is Ecology?
 Eco comes from Greek word “oikos” – house
 -logy comes from “logos” – study of
 Ecology means “study of the house” as coined by
Ernst Haeckel
 Ecology – the study of interactions among organisms
(plants and animals) and their environment
Levels of Organization (page 397
Figure 13.2)
 From individual to global:
 Organism—individual living thing (ex. Lion)
Levels of Organization
 Population—group of same species that live in one area
(ex. Pride of lions)
Levels of Organization
 Community—collection of interacting populations (ex.
Lions, antelope, zebras, elephants, grasses, etc…)
Levels of Organization
 Ecosystem—interactions of biotic and abiotic
factors in an area
 Biotic factors—living or once living things (ex.
Animals, plants, microorganisms, etc…)
 Abiotic factors—nonliving things (ex.
Sunlight, temperature, soil, etc…)
Levels of Organization
 Biome—regional or global community of
organisms which is usually characterized by the
climate conditions and plant communities that
thrive there
Section 13.2
 In an ecosystem, each living thing depends on an array
of biotic factors and abiotic factors in the ultimate web
of life.
 A single change in that web can lead to minor or major
changes.
 A keystone species is one that has an unusually large
effect on its ecosystem. (ex. Beaver) (ex. Killing too
many deer during hunting season)
Section 13.3 Energy in Ecosystems
(page 406)
 Autotrophs—“self feeder”
 Heterotrophs—“different feeder”
 Producers —obtain energy from the sun (by
photosynthesis pg 407) or chemicals (by
chemosynthesis pg 407) and convert it to a useable
form of energy (like food, sugar, carbohydrates)
 What kind of feeders are these?
Section 13.3
 *All ecosystems depend on producers, because they
provide the basis for the ecosystem’s energy.
 Consumers—get their energy by eating other living or
once-living organisms (like autotrophs and/or other
heterotrophs)
 What kind of feeders are these?
Types of consumers: (page 409)
 Herbivores—obtain energy from eating plants
 Omnivores—obtain energy from eating plants and
animals
 Carnivores—obtain energy from eating animals
Types of Consumers
 Detritivores—obtain energy from eating detritus or
dead organic material (ex. Earthworm)
 Decomposers—obtain energy from breaking down
organic matter (dead) into simpler molecules that can
be more easily absorbed by decomposers and by other
organisms
 Why would they by important?
 Important in an ecosystem to return vital nutrients back
into the environment
Section 13.4 Food Chains and Food
Webs
 To show energy transfer between different species, a
food chain can be constructed.
 A food chain is a linear sequence that links species by
their feeding relationships.
 Matter and energy move through an ecosystem by use of
arrows
 Example: autotroph→heterotroph→decomposer
 *Heat energy is lost in each step
Trophic Levels
 Trophic levels are the levels of nourishment in a food
chain
 Example: producer→herbivore→carnivore
 Chain has 3 trophic levels
 1st trophic level  producer (base)
 2nd trophic level  primary (1’) consumer (herbivore),
first order
 3rd trophic level  secondary (2’) consumer
(omnivore/carnivore), second order
 4th trophic level  tertiary (3’) consumer (omnivore/
mostly carnivore), third order (top level)
 Energy flows through an ecosystem in ONE direction
 Food web- links all the food chains in an ecosystem
 The stability of any food web depends on the presence
of producers, as they form the base of the food web
Section 13.6 Pyramid Models
 Each level in the food chain contains much less energy
than the level below it. The sun continually pumps
new energy into the system to continue life.
 Only about 10% of the available energy is transferred
to the next trophic level. Maximum number of
organisms in a food chain is 5 because of energy loss.
 Where does the rest of the energy go?
 An energy pyramid compares energy used by
producers, primary consumers, and other trophic
levels (in units of kilocalories, kcal) see figure 13.17 on
page 418
 A biomass pyramid provides a picture of the mass of
producers needed to support primary consumers, the
mass of primary consumers required to support
secondary consumers, and so on.
 A pyramid of numbers shows the numbers of
individual organisms at each trophic level in an
ecosystem.
 Biomass pyramids and pyramids of numbers may
occur in an inverted, or upside down formation. What
might this indicate about that ecosystem?