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5 Levels of Ecological
Organization
§ Species- organisms that can
interbreed and produce fertile
offspring
§ Population- all the members of 1
species in an area
§ Community- every species in an area
§ Ecosystem- many communities and
their environment
§ Biosphere- the entire region of Earth
where living things can be found
(many ecosystems)
What is Ecology?
§ Ecology- study of the interaction
between organisms and their
environment
§ Within an ecosystem there are two
main components
Habitat- place where organism
lives
Community- ALL the species in
habitat
Biomes
§ Biomes are groups of terrestrial ecosystems
that have the same climate and dominant
communities
§ 3 types of biomes:
l Temperate: seasonal
l Tropical: by equator and hot year round
l Arctic: far from equator and cold year
round
§ You have forests, deserts and grasslands in
these different areas
Biomes
Aquatic Lifezones
§ Aquatic lifezones are aquatic ecosystems.
§ Freshwater or saltwater
§ Freshwater
l Wetlands are very important ecosystems
l Bogs, swamps or marshes
l Rivers
l Ponds
l Estuaries (wetlands where river meets sea)
l Mangrove swamps
§ Saltwater (Marine)
l Coral Reefs
l Intertidal zone
l Open ocean
§ Biomes-22min
Species Interaction
§ Many interactions take
place between species
in a community
i.e.) predator and
prey
§ Each organism plays a
certain role in the
community
§ Niche- role of an
organism in which it
interacts with other
species and its
environment (i.e. its
job)
Abiotic vs. Biotic Factors
§ Abiotic- “non-living”
components
-ex) temperature, light,
water, nutrients, boats
§ Biotic- “living” species
-ex) sea turtle, sea grass,
coral, fish, humans
Biotic Factors
§ Two categories of life based on how they
get energy
§ All life is either a
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Producer OR
Consumer
Biotic Factors
§ Producers- organisms that are capable of
producing their own energy source
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Photosynthetic (plants that take light to make carbs)
Chemosynthetic (some bacteria that can take
chemicals to make their carbs)
All producers are autotrophs or “self-feeders”
KNOW THIS EQUATION!
Biotic Factors
§ Consumers- organisms
that can’t produce their
own energy source, but
have to consume it from
another source
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All consumers are
heterotrophs or “other
feeders
§ Many different types of
consumers (heterotrophs)
-Herbivores
-Carnivores
-Omnivores
-Decomposers
Look at each of the pictures and write in the
space below it whether it is a
producer or a consumer
Conditions for Life
§ For an ecosystem to sustain life,
it must have:
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1) Constant source of energy (sun).
2) Living system that converts sun’s
energy into organic molecules.
Plants!
3) Cycling of nutrients between
organisms and environment (water,
carbon dioxide, nitrogen, oxygen).
4) Decomposers- bacteria and other
small organisms that breakdown and
return unused nutrients to the
environment.
Biodiversity
§ Biodiversity- The
number of
different species
in an ecosystem
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More plants =
more animals
More biodiversity
= healthier
ecosystem
What Determines Biodiversity
of Ecosystem?
§ Size
§ Latitude – Closer to
equator = more diverse.
a) More sunlight and
longer growing season
b) More producers
(plants)
Why do we call plants
producers?
c) More producers =
more consumers
§ Precipitation (i.e. rainfall)
Nutritional Interactions
§ All ecosystems must have
interactions between
producers, consumers, and
decomposers
§ These interactions
transfer nutrients and
energy throughout the
ecosystem
Energy flow in an
ecosystem
§ Energy flows through an
ecosystem from the sun to
producers to consumers
§ ***Arrows show the direction
the energy flows
“Who Eats Who”…
§ Food chain- straight line
sequence shows simple
feeding relationships
§ Notice the direction of
the arrows!
§ Sun
§ Producers
§ Primary consumers
§ Secondary Consumers
§ Tertiary Consumers
OWL
Quaternary
consumer
FLOWER
Producer
FROG
Secondary
consumer
CATERPILLAR
Primary consumer
SNAKE
Teriary
consumer
§ Food webillustrates how many
food chains in an
ecosystem are
related
§ Primary consumers?
§ Secondary
consumers?
§ Tertiary consumers?
§ Where would
decomposers fit in
this food web?
How many trophic levels
are possible?
§ Energy pyramids- show amount of energy
at each trophic level
§ These are not food pyramids!!
§ Trophic levels -levels of feeding from
producers (plants) to the consumers
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Few ecosystems have more than 4 or 5 trophic
levels
Energy diminishes at each level because it is
used for life’s processes
Pyramid of Energy
§Which level has the most energy
AVAILABLE?
§ Trophic levels
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Producers have the
most energy
available
Primary consumers
are all herbivores
Secondary
consumers are small
carnivores
Tertiary consumers
are large carnivores
§ Part of the original
energy from the
sun is used at
every level by the
organisms for
survival
How do organisms obtain
nutrients?
§ Although energy moves through
ecosystems in a one-way direction,
nutrients are recycled
§ Three basic nutrient cycles are present in
all ecosystems allowing organisms to
obtain needed nutrients to function
effectively
Nitrogen Cycle
§The atmosphere contains
80% nitrogen gas (N2)
§However, this nitrogen can
not be used by most living
things
§Bacteria are the only
organisms that use nitrogen
gas directly from the
atmosphere
§They can fix nitrogen for
plants to use by converting it
into ammonia
N2
DNA and proteins
Nitrogen Cycle Processes
§Nitrogen fixation- nitrogen
N2
gas in atmosphere
converted to ammonia, NH3
(bacteria in soil, lightning)Nitrogen fixation
§Nitrification- bacteria
converting ammonia to
NH3
nitrate (another form of
nitrogen)
§Assimilation- absorption Nitrification
of ammonia and nitrate by
plants
YUMMY!
Assimilation
Nitrate
Nitrogen Cycle Processes
§ Ammonificationdecomposers (bacteria
and fungi) break down
of dead organisms
and waste and return
nitrogen to soil as
ammonia
§ Denitrificationconversion of
ammonia back to
nitrogen gas
(decomposers)
N2
Denitrification
Ammonification
NH3
Nitrogen Cycle
Review Nitrogen
Importance
§ Why is nitrogen important to living things?
§ How do plants obtain nitrogen?
§ Why are bacteria SO important to the
nitrogen cycle?
§ How do we obtain nitrogen?
§ Nitrogen cycle movie with QUIZ
Water Cycle
§ Driving force is the sun and gravity
§ Consists of the alternation between
evaporation and precipitation
§ Most water returned to the
atmosphere comes from evaporation
from the oceans
Water Cycle Processes
§ Water vapor- gaseous form of water in
atmosphere
§ Evaporation- liquid water from bodies of
water becomes gas returned to
atmosphere
§ Transpiration- loss of water by
land plants
Water Cycle Processes
§ Condensationprocess which water
molecules gather in
atmosphere “change
from gas to liquid”
when cooled
§ Precipitation- water
falls from atmosphere
to ground (rain, snow,
sleet, or hail )
Water Cycle
What is missing here?
Why is the water cycle
important?
§ Water is the most
important nonliving
(abiotic) component of an
ecosystem
§ Water essentially
determines what organisms
we find in an ecosystem
l Tropical rainforest vs.
desert
Carbon Cycle
§ Carbon cycles between the living
organisms and the non-living
components of ecosystem
§ Carbon exists in the atmosphere as
carbon dioxide (CO2)
§ Plants are of great importance to
the carbon cycle!!—photosynthesis
takes carbon from the air and
creates glucose for all consumers to
use
§ Why do living things need carbon?
6
C
Carbon
12.011
Carbon Cycle Processes
§ Photosynthesis- process where sunlight, CO2
and H2O is used to make carbs.
CO2 + H2O + sunlight (energy)  glucose (carb) +O2
§ Respiration- process by which animals use carbs,
taking in O2 given off by plants and give off CO2
***THE OPPOSITE OF PHOTOSYNTHESIS!
glucose (carb) + O2  CO2 + H2O + energy to live
Respiration
§ The energy for life’s processes comes from cellular
respiration, which occurs in your mitochondria
glucose (carb) + O2  CO2 + H2O + ATP energy
Carbon that you eat is used
to build other organic
macromolecules or is exhaled
This carbon that you exhale
is from the food you eat
Carbon Cycle Processes
§ Decomposition—breakdown of dead
organisms and waste, returning carbon
to the soil and atmosphere
§ Fossil fuels- formed by pressure applied
to dead organisms that are buried in
sediment. They are carbon and release
CO2 when burned.
§ Combustion- burning of fossil fuels
Carbon Cycle
Why is the carbon cycle important?
§ Organic macromolecules – carbon compounds
used for energy for living organisms
(carbohydrates), cell membranes (lipids),
DNA/RNA, and proteins.
§ ***Humans are altering this cycle
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Deforestation releases stored carbon
CO2 from burning is a greenhouse gas which warms
the planet
Why is the carbon cycle
important?
§ Burning too many fossil fuels
releases extra CO2 into the
atmosphere
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This creates climate change
due to increased greenhouse
effect
The greenhouse effect is
normal
Climate change is due to
abnormally high levels of the
greenhouse effec
Greenhouse effect video clip
Average Surface Temperature (°C)
Average Temperature Over Past 130
Years
15.0
14.8
14.6
14.4
14.2
14.0
13.8
13.6
1860
1880
1900
1920
1940
Year
1960
1980
2000
2020
What is the Scientific Consensus?
Mean global temperature
rose about 0.6º C (1.5º F)
since 1880
1979--NASA
Increase is real, not
explained by natural
variation in solar radiation
Warming greater at poles
than equator, greater at
night, mostly troposphere
September sea ice level
animation
2003--NASA
How competition effects
ecosystems
§ Sometimes two species will compete
§ Competitive exclusion- no two species can
occupy the exact same niche (job) for a long
period time
§ Only one species wins
What if no one wins?
§ In some species
interactions, neither
species wins
§ This results in close,
long term
associations within
an ecosystem called
symbiotic
relationships
§
§
§
§
3 Kinds of Symbiotic
Relationships
+=helped
- = harmed
0=neither
Parasitism (+/-)
§ Commensalism (+/0)
§ Mutualism (+/+)
Evolution and Ecology
§ Symbiotic relationships
cause species to evolve in
response to each other
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Ex) Flowers pollinated by
nocturnal moths
§ Coevolution- evolution of
two or more species in
response to one another
§ Ant and Fungus Symbiosis
Changing Ecosystems
• Infer….what do you think is the story behind the
picture?
• Changes are a natural part of any ecosystem
• Succession- regular development of an ecosystem which
leads to gradual replacing of species in a community by
others
• Succession and the
Mount
Ecosystem Stability
§ Does succession ever end?
§ Climax community
§ Stability - ability of an ecosystem to resist
change when a disturbance occurs
§ Biodiversity tends to promote stability
Ecosystem Stability
§ Keystone speciesspecies that are
crucial to the
stability of an
ecosystem
§ If members of a
keystone species die,
then the entire
ecosystem can
collapse
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i.e. sea otters- keep
sea urchins in check,
which would take over
the kelp beds without
the otters
Ecosystem Stability
§ Invasive, or introduced
species- those that are
brought by humans
accidentally or
purposefully from other
places
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Invasive/introduced species
can take hold and destroy
ecosystems.
They multiply out of control
due to lack of predators in
new place they are moved
to.
Ex: Asian longhorn beetle,
Zebra mussels
SEA LAMPREY
Population Dynamics
§ Population-a group of organisms of the
same species that occupy a given area
§ Living things reproduce
§ If environmental conditions are
“favorable,” then the number of
individuals in population should increase
from one generation to next
Population Size- Growth Rate
Birth rate- # individuals born
Death rate- # individuals die
Immigration- # individuals move in
Emigration- # individuals move out
If…
BR + I = DR + E EQUILIBRIUM
BR + I > DR + E INCREASING
BR + I < DR + E DECREASING
§ Population growth video clip
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§
§
§
§
Biotic Potential
§ Under favorable
conditions, a species may
reach its biotic potential
§ Biotic potential- highest
reproduction rate
possible for a species
under “ideal” conditions.
Ex) Houseflies
-Lay over 100 eggs at once
-Can reproduce at 1 month
old
-After 7 generations,
one fly = 15 billion flies!!!
Exponential Growth
§ Exponential
growth- starts out
slowly but then
grows rapidly to
infinitely high
numbers
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Represented by “J
curve”
This does NOT
describe real
populations
forever
§ Something always
limits growth
eventually
biotic
potential
Factors Affect Growth Rate
Size of Population
§ Environmental resistance- “limiting factors”
that stop populations from reaching their
biotic potential
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Space
Water
Nutrients
Competition
Disease
Natural disasters
Logistic Growth
§ Real populations can
only grow
exponentially for
short spans.
§ Environmental
resistance limits size
of a population.
§ Logistic curvepopulation growth
that levels off due
to environmental
resistance
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“S” curve
Carrying Capacity
§ Carrying capacitytotal # of individuals
that can be
supported by the
environment in a
particular area
§ Earth has over 7
billion people…how
many more can it
support?
§ Population Crash
The Human Population
World Populaton Clock
§ The human population is
growing exponentially at
1% a year
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Adding 1 million people
every 5 days
§ Remember that
exponential growth
cannot continue
forever
§ Humans are subject to
the same laws of nature
as all other species
Problems with Overpopulation
Humans, more than anything else, are affecting the
stability of Earth
§ 1.) Food supply increased over past few decades,
but amount per person has decreased
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Many people starving, and this will continue to get
worse as over 90% of future population growth is
expected to occur in less developed nations
Over-fishing
Erosion and pollution of agricultural land
Problems with Overpopulation
§ 2.)Energy shortage
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Nonrenewable resources
are limited and we are
using them faster than
ever before
• Less developed
nations who are
developing will
continue to use more
fossil fuels
• The U.S., with 5% of
the world’s
population, uses 25%
of the world’s energy
resources
• Pollutants are
increasing as well as
climate change
Problems with Overpopulation
§ 3.)Destruction and abuse of natural resources
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Topsoil
Forests
Freshwater supplies diminished
Species extinction
Problems with Overpopulation
§ 4.)Pollution
• Production of tons of
unnecessary solid waste
• Water
• Air
– Climate change due
to burning and
deforestation
increasing carbon
dioxide levels
– Acid rain
– Ozone depletion
Ozone Layer Depletion
§ Ozone shield
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Ozone (O3) in the atmosphere
protects us by absorbing
harmful UV light
1970s scientists discovered the
ozone layer over Antarctica
has decreased by as much as
60 %
§ Problems?
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UV light is a mutagen, which
can cause skin cancer
Cataracts