Chapters 4-5
Unit 4
Ecology
•Studying Ecology
•Describing
Populations
•Energy movement
through the
ecosystem
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Unit4 Vocabulary (30)
Abiotic factor•
•
Autotroph
•
Biotic factor
•
Carnivore
•
Community
•
Consumer
•
Decomposer •
•
Detrivore
•
Ecology
Ecosystem
Habitat
•
Herbivore •
Heterotroph •
•
Omnivore
•
Population •
Producer
Resources •
Species
•
Biomass
Ecological
•
efficiency
•
Food chain
Food web
Keystone species
Primary consumer
Primary producer
Primary
productivity
Pyramid of
energy
Pyramid of
numbers
Secondary
consumer
Trophic level
Levels of Ecological Organization
• Ecology – Study of how organisms interact
with each other & with their environment
• Individuals
Populations
Communities
Ecosystems
Biosphere
• Individual species – can interbreed and
produce fertile offspring
• Population – members of a species that live
in the same area at the same time
• Community – all of the populations in a
particular area
• Ecosystem – living & nonliving
Biotic & Abiotic Factors
• Biotic factors – parts
of the ecosystem that
are living or used to
be living
• Abiotic factors –
parts of the
ecosystem that have
never been living
Habitat
• Habitat – specific
environment in which an
organism lives
• Organisms depend on
resources provided by their
habitat for survival
• Resource – anything an
organism needs, incl.
nutrients, shelter, mates
Small Group
• For all the levels of ecological
organization (individuals to
biosphere), state whether it
contains only biotic factors, only
abiotic factors, or both. Then,
write a question that an ecologist
might ask when studying life at
each of the levels.
• Section 4.1 Review
What is a population?
Individuals of the same
species living in a
particular area
Species can consist of
many populations that
are geographically
isolated
Population Size
• The number of individual
organisms present in a given
population at a given time
• This may increase, decrease,
undergo cyclical change or
remain the same over time
• When size decreases quickly,
it could mean extinction is
coming
Passenger Pigeon
• Ex. of extremes of pop. size
• Once the most abundant
bird in North America
• Nested & bred in the
forests of upper Midwest
and southern Canada
• Deforestation led to over
hunting
• Extinct by 1914
Limiting Factors
• Characteristics of the
environment that limit
population growth
• Can be biotic or abiotic
• Ex’s: oxygen, sunlight,
nutrients, available mates,
competition, …
Ecological Communities
• Life requires energy!
• Organisms are classified as
either producer or consumer
based on how they obtain
energy
• Primary producers capture
energy from the sun or other
chemicals and then store it in
the chemical bonds of sugars
• Autotroph = self-feeder
Photosynthesis
• For almost all ecosystems,
the sun is the ultimate
energy source
• Primary producers include
plants, algae, cyanobacteria
• Turn light energy into
chemical (bonds) energy
• CO2 & H2O is converted
into C6H12O6 & O2
Chemosynthesis
• Deep-sea vents host entire
communities of organisms
• Complete lack of sunlight
• Primary producers such as
bacteria use H2S to convert
CO2 & H2O into sugars
• Chemosynthesis uses a
different energy source, but
like photosynthesis, it uses
water & carbon dioxide to
produce sugars
Small Group Activity
CO2 + H2O + energy
C6H12O6 + O2
1. List examples of autotrophs
2. Describe their role in energy production
3. List some factors that might influence
photosynthesis
4. Explain why some organisms might use
chemosynthesis
5. Compare/contrast photosynthesis and
chemosynthesis (Venn diagram)
6. What is each’s source of energy?
Consumers
• Organisms that rely on other
organisms for energy and nutrients
• Also called heterotrophs or “other
feeder”
• Use cellular respiration to release
the energy from bonds created in
photosynthesis or chemosynthesis
• Consumers & Producers use O2 with
glucose to release CO2 & H2O as
byproducts and make ATP energy
• Primary consumers - organisms
that consume producers
• Herbivores – organisms that only
consume plants
• Secondary consumers –
organisms that consume the
primary consumers & herbivores
• Tertiary consumers eat the
secondary consumers
• Carnivores – eat only other
animals
• Omnivores – eat both plant and
animal food
• Parasite – does not kill its host*
Detritivores & Decomposers
• Recyclers who help nutrients reenter the ecosystem
• Detritivores consume detritus –
nonliving organic matter like
leaf litter, waste products, dead
bodies (ex. millipedes, beetles)
• Large detritivores are called
scavengers (ex. vultures)
• Decomposers break down
nonliving matter for reuse by
primary producers (ex. fungi,
bacteria)
Trophic Levels
• An organism’s trophic level is its
rank in a feeding hierarchy
• Primary producers always make
up the community’s 1st trophic
level
• 10% Rule – each trophic level
contains just 10% of the energy
of the trophic level below it
• You lose 90% of the original
energy in the energy used in life
Biomass
• Similar to available energy,
there are generally fewer
organisms at higher
trophic levels than at lower
ones
• Biomass is the total amount
of living tissue
• For every hawk, there are
more snakes, still more
mice, and a huge # of
plants
Energy & Biomass
• Energy tranfers from one trophic
level to another within a community.
• Its efficiency is only about 10%.
• If 1000 units of energy are available
at the producer level of the energy
pyramid, about how many units are
available for primary consumers?
• For secondary consumers?
• For tertiary consumers?
• Why do most communities have only
about 3 or 4 trophic levels?
Food Chains & Webs
• Food chain – a single linear
series of feeding relationships
(what eats what now) and
shows how energy moves up the
trophic levels (arrows point
which way?)
• Feed web – a more accurate
representation of feeding
relationships in a community;
a visual map of all the feeding
relationships and energy flow
Don’t forget the decomposers,
scavengers and detritivores in the
community food web.
Florida Food Webs
• How are they unique?
• How are they similar to other parts of the US?
Keystone Species
• Some species have greater
influence than others
• Keystone species have a
strong, wide-reaching
impact on the community;
its removal can alter a
large portion of the food
web
• Exs. – sea otters, wolves,
black bear, alligator.
Small Group Work
• Section 5.3 packet
• Answer the following:
1. Explain the difference between a
producer & a consumer. Then explain the
difference between herbivors, carnivore,
omnivore, detritivore, and decomposer.
2. Write a paragraph arguing that
decomposers are a “keystone group.”
Community Stability
• Ecological succession –
predictable series of changes
over time that occur to a
community
• Two types of succession:
1. Primary succession
– No life existed
2. Secondary succession
– Soil already present
– Removal of biota
Primary
Succession
• When a disturbance is so severe,
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there is no vegetation or soil life
A community is built from scratch
Takes place on bare rock, sand or
sediment that is exposed for the
first time
Pioneer species – species that
colonize newly exposed land first,
often have spores or seeds that
can travel long distance. Ex. Lichen
Ex. – glacier retreat, volcano, dry
lake
Secondary Succession
• A disturbance (fire, flood,
farming, paving) alters an
existing community but does not
destroy all living things or
organic matter
• The soil remains
• Occurs faster than primary
succession
• Usually grasses to shrubs to
fast growing trees to
hardwoods
Climax Communities
• Succession eventually
leads to a climax
community
• A stable community that
completes the succession
process
• Ex. Beech-maple forests
in the NE US, oak, spruce
Invasive Species
• Nonnative, exotic species that
spreads widely in a community
• Become invasive when limiting
factors are not present in their
new environment (predators,
parasites, competitors)
• Not all are bad
• Ex. – zebra mussels, cane toad,
kudzu, honey bees