Transcript organism

Principles of
Ecology
Ch. 13
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13.1 Ecologists study relationships
Ecology: the study of the interactions
among living things, and
between living things and
their surroundings.
Eco = environment
ology = study of
This is studied at different levels
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LEVELS OF ORGANIZATION
1. organism - an individual living
thing, such as an alligator.
Organism
Organism
LEVELS OF ORGANIZATION
2. population is a group of the same species
that lives in one area.
- Several alligators living together.
Population
Population
Organism
Organism
LEVELS OF ORGANIZATION
3. A community is a group of different
species that live together in one area.
- Alligators, birds, fish, plants
all living together in a swamp.
Community
Community
Population
Population
Organism
Organism
LEVELS OF ORGANIZATION
4. An ecosystem includes all of the
organisms as well as the non-living things
such as; climate, soil, water, rocks and
other in a given area.
Ecosystem
Ecosystem
Community
Community
Population
Population
Organism
Organism
LEVELS OF ORGANIZATION
5. 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
Ecological research methods include
observation, experimentation, and modeling.
Observation
•Direct surveys used for easy to spot
and follow species employ binoculars
or scopes.
•Indirect surveys are used for species
that are difficult to track and include
looking for other signs of their
presence.
•Feces or a recent kill.
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Quadrat Sampling
1. _____________________________________
TAGGING / RADIO TELEMETRY
2. _____________________________________
Mark and Recapture –
3. _____________________________________
•Capture a number organismsmark/tag them
•Recapture a portion
•The number of marked
organisms if proportional to the
size of the whole population.
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What is the
population of
turtles in the
rectangle:
_______
MEASURE THE SIZE OF THE SQUARE:
_______________
TIME YOURSELF AND COUNT THE NUMBER
OF TURTLES: ____
DETERMINE HOW MANY SQUARES CAN FIT
INTO THE LARGER RECTANGLE ON THE
PREVIOUS PAGE: _________
CALCULATE THE POPULATION OF TURTLES
IN THE RECTANGLE:
___________________________________
Where your two numbers relatively close? _____________________
What is the advantage of quadrat sampling? _____________________
What is the disadvantage of quadrat sampling? _____________________
What type of organism do you think would be best suited for quadrat
sampling? ____________________________________________________
Experiments: Performed in the lab or in
the field.
• Lab experiments:
• Positive = More control
• Negative = Doesn’t always reflect
what happens in nature
•Field experiments:
• Positive = More accurate picture of
what happens in nature
• Negative = May not help determine
cause and effect
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Modeling:
•Computer and Mathematical models
• “What would happen if…”
• Predict outcomes
• Allows scientists to learn about
organisms or ecosystems in ways that
would not be possible in a natural or
lab setting.
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1. What are the five different levels of organization studied by
ecologists?
2. Describe the three general methods used by ecologists to
study organisms.
3. What ecological research methods would you use to study bird
migration? Explain your choices.
4. How might an ecologist use modeling to study fire in a forest
ecosystem? What might be some key variable used to create
the model?
13.2 Biotic and Abiotic Factors
ALL LIVING THINGS
BACTERIA-PROTIST-FUNGUS-PLANTS-ANIMALS
ALL NON-LIVING THINGS
WATER-SUN-SNOW-CLOUDS-ROCKS-MOUNTAINS
Changing one factor can affect many other
factors
Biodiversity
Biodiversity is the assortment, or variety, of living
things in an ecosystem.
Rainforests have more biodiversity than other
locations in the world, but are threatened by
human activities.
•
•
Keystone species is a species that has an unusually
large effect on its ecosystem.
Example = Beaver
keystone
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creation of
wetland
ecosystem
increased waterfowl
Population
keystone species
increased fish
population
nesting sites for
birds
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1. Select an ecosystem that is familiar to you and describe the
biotic and abiotic factors that exist there.
2. How would the removal of a keystone species affect an
ecosystem’s biodiversity?
3. Name an abiotic factor. Explain how a change in an abiotic
factor would affect biodiversity.
4. Humans are sometimes described as being a keystone
species. Does this label fit? Why or why not?
13.3 Energy in Ecosystems`
Producers provide energy for other organisms in an
ecosystem.
Producers- make their own food – also called
autotrophs
Consumers – get energy by eating – also called
heterotrophs
•
•
Almost all producers obtain energy from sunlight.
Photosynthesis in most producers uses sunlight as
an energy source.
Chemosynthesis in prokaryote (bacteria) producers
uses chemicals as an energy source.
Video clip
•
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1. How does the stability of an ecosystem depend on its
producers?
2. What are the two processes used by producers to obtain
energy?
3. Few producers live deep below a lake’s surface. Suggest an
explanation for this pattern.
4. Could producers survive without consumers? Explain why or
why not?
5. Could consumers survive without producers? Why or why
not?
13.4 Food Chains and Food Web
Food chains and food webs model the flow of
energy in an ecosystem.
Show feeding relationships for one chain of
producers and consumers in an ecosystem
Arrow always points in the direction the energy is
going.
•
•
GRAMA GRASS
DESERT COTTONTAIL
HARRIS’S HAWK
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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.
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•Specialists are consumers that primarily
eat one specific organism or a very
small number of organisms.
Ex: Florida Snail Kite – eats only
snails
•
• Generalists are consumers that have a
varied diet.
Ex: Grey wolf
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Trophic Levels- Feeding 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.
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Food Web
•Shows many
interconnected food
chains in an
ecosystem
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Identify three food chains from this food web.
copyright cmassengale
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1. Name the producers in the salt marsh community. ___________________________
2. Name four primary consumers in the salt marsh community. __________________
___________________ ___________________ _____________________
3. Name four secondary consumers in the salt marsh community. _________________
___________________ ___________________ _____________________
4. Name an animal in the salt marsh community that eats both plants and animals.
_________________________________________________________________
5. Name the two animals at the top of the salt marsh food web.
_________________________________________________________________
6. Why are the decomposers shown as the are in this picture?
__________________________________________________________________
7. Who is the “highest’ consumer? ________________________________
copyright cmassengale
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1. Why are food chains especially useful for describing the
relationships of specialists?
2. What happens to energy as it flows through a food web?
3. Only a small percentage of all consumers are specialists.
What danger does a specialist face that a generalist does
not?
4. How might the stability of an ecosystem be affected if all the
decomposers were suddenly removed?
Water cycles through the environment.
•The hydrologic, or water cycle is the circular
pathway of water on Earth.
•Organisms all have bodies made mostly of water.
precipitation
condensation
transpiration
evaporation
lake
groundwater
surface
runoff
water storage
in ocean
Elements essential for life also cycle through
ecosystems.
• A biogeochemical cycle is the movement of a chemical
through the biological and geological parts of an
ecosystem.
• The Oxygen cycle involves photosynthesis and respiration.
•Oxygen cycles
indirectly through an
ecosystem by the
cycling of other
nutrients.
Carbon is the building block of life.
• The carbon cycle moves carbon from the atmosphere,
through the food web, and returns to the atmosphere.
• Carbon is emitted by the burning of fossil fuels.
• Some carbon is stored for long periods of time in areas
called carbon sinks.
carbon
dioxide
in air combustion
respiration
photosynthesis
respiration
decomposition
of organisms
fossil fuels
photosynthesis
carbon dioxide
dissolved in water
The nitrogen cycle mostly takes place underground.
• Some bacteria convert gaseous nitrogen into ammonia
through a process called nitrogen fixation.
• nitrogen-fixing
bacteria live in
roots of plants; others
live freely in the soil.
• bacteria change the
ammonium into
nitrate.
• moves through the
food web and returns
to the soil during
decomposition.
nitrogen in
atmosphere
animals
plant
nitrogen-fixing
bacteria in
decomposers
roots
ammonification
nitrogen-fixing
ammonium
bacteria in soil
nitrifying
bacteria
nitrates
nitrifying
bacteria
nitrites
denitrifying
bacteria
The phosphorus cycle takes place at and below ground
level.
• released by the weathering of rocks.
• moves through the food web and returns to the soil
during decomposition.
• leaches
into groundwater
from the soil and
is locked in
sediments.
• added to environment
by both mining and
agriculture
rain
plants
geologic uplifting
weathering of
phosphate from rocks
runoff
animalsphosphate
phosphate in solution
in soil
leaching
decomposers
sedimentation
forms new rocks
• How does the hydrologic cycle move water through the
environment?
• What are the four elements that cycle through ecosystems and
why are they important?
• Why might farmers plants legumes such as peas to improve the
nitrogen levels in their soil?
• Explain the importance of decomposers to the overall
biogeochemical cycle
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An energy pyramid shows the distribution of
energy among trophic levels.
• Energy pyramids compare energy used by
producers and other organisms on trophic
levels.
• Up to 90 percent of the
energy = lost as heat
between each level
• Only 10 percent of the
energy at each tier is
transferred from one trophic
level to the next.
energy
lost
energy transferred
Pyramids for Biomass and numbers
•Biomass is a measure of the total dry mass of
organisms in a given area.
tertiary
consumers
75 g/m2
150g/m2
secondary
consumers
primary
consumers
producers
producers
675g/m2
2000g/m2
A pyramid of numbers shows the numbers of
individual organisms at each trophic level in an
ecosystem.
tertiary
consumers
5
secondary
consumers
5000
primary
consumers
500,000
producers
producers
5,000,000
• A vast number of producers are required to support
even a few top level consumers.
1. How does an energy pyramid help to describe energy flow in a
food web?
2. What is the difference between a biomass pyramid and a
pyramid of numbers?
3. How would you draw a pyramid of numbers for a dog with
fleas? What shape would the pyramid take?
4. If each level in a food chain typically loses 90% of the energy it
takes in, and the producer level uses 1000 kilocalories of
energy, how much of that energy is left after the third trophic
level?