What is
Ecology?
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What is Ecology??
• The study of interactions
that take place between
organisms and their
environment.
• It explains how living
organisms affect each other
and the world they live in.
2
Habitat & Niche
• Habitat is the
place a plant or
animal lives
• Niche is an
organism’s total
way of life
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The Nonliving Environment
• Abiotic factors- the
nonliving parts of an
organism’s environment.
• Examples include air
currents, temperature,
moisture, light, and soil.
• Abiotic factors affect an
organism’s life.
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The Living Environment
• Biotic factors- all the
living organisms that
inhabit an environment.
• All organisms depend on
others directly or
indirectly for food,
shelter, reproduction, or
protection.
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Which are
abiotic
factors?
Which are
biotic
factors?
Levels of
Organization
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What are the Simplest Levels?
• Atom
• Molecule
• Organelle
• Cell
• Tissue
• Organ
• System
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Levels of Organization
• Ecologists have organized the
interactions an organism takes part
in into different levels according to
complexity.
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1st Level of Organization
• Organism:
An individual
living thing that is
made of cells,
uses energy,
reproduces,
responds, grows,
and develops
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2nd Level of Organization
• Population:
A group of
organisms, all
of the same
species, which
interbreed and
live in the same
place at the
same time.
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3rd Level of Organization
• Biological
Community:
All the
populations of
different
species that live
in the same
place at the
same time.
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4th Level of Organization
• Ecosystem:
Populations of plants and
animals that interact with
each other in a given area
with the abiotic components
of that area.
(terrestrial or
aquatic)
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5th Level of Organization
• Biosphere:
The portion
of Earth
that
supports
life.
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The Biosphere
• Life is found in air, on land,
and in fresh and salt water.
• The BIOSPHERE is the
portion of Earth that
supports living things.
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What level of organization?
Organism
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Which level is this?
• Population
Which level is this?
• Community
Which level is this?
• Individual organism
What level of Organization?
Population
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Which level is this?
• Ecosystem
What level of Organization?
Community
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Symbiosis
• A close relationship between two organisms
There are 3 types of symbiosis…
Symbiosis
• Def. – the way two different species live together
• Mutualism – both organisms benefit from their
relationship (cleaning shrimp; termites)
• Commensalism – one organism benefits and the
other neither benefits nor is harmed (little fishies
that follow the sharks, they are too small for the
shark to eat, but they feed on the pieces of food
that the shark drops)
• Parasitism – one organism benefits, while the
other is harmed (tapeworms)
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Mutualism
The bird picks bugs off of the
larger animal and eats them.
The larger animal gets rid of
pests.
The butterfly gets food
from the flower. The flower
gets pollinated as the
butterfly travels between
different plants.
Commensalism
The smaller remora shark hitches a ride attached
to a larger animal (usually a whale or another
shark). It eats scraps of food leftover from the
larger animal’s meals. The larger animal is
unharmed.
Parasitism
The fly lays
its eggs
within the
larvae of
another
animal. When
the fly eggs
hatch, they
eat the
surrounding
tissues of the
victim.
Interactions
• Even though some organisms can live with each
other “peacefully”, we must take into consideration
survival.
• Predator-Prey Relationship – one organism hunts
another organism for food
• Competition – two different organisms have to
compete against each other for the same resource
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Energy Flow in
an Ecosystem
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Energy Flow
• Energy in an ecosystem originally
comes from the sun
• Energy flows through Ecosystems
from producers to consumers
– Producers (make food)
– Consumers (use food by eating
producers or other consumers)
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Producers
• Sunlight is the main
source of energy
for most life on
earth.
• Producers contain
chlorophyll & can
use energy directly
from the sun
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Autotrophs
• An Autotroph is any organism
that can produce its own food
supply!
• Autotrophs are also called
Producers
• Plants, algae, some protists, &
some bacteria are examples
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Niche of a Producer
• Captures energy and transforms
it into organic, stored energy for
the use of living organisms.
• May be photoautotrophs using
light energy (e.g. plants)
• May be chemoautotrophs using
chemical energy (e.g.
cyanobacteria)
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Photoautotroph
Producer That Captures Energy
from the sun by:
– Photosynthesis
• Adds Oxygen to the
atmosphere
• Removes Carbon Dioxide from
the Atmosphere
Algae
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Habitat of Photoautotrophs
• On Land
– Plants
• In The Sea
– Algae
• Tidal Flats & Salt Marshes
– Cyanobacteria
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Chemoautotrophs
• Capture energy from
the bonds of inorganic
molecules such as
Hydrogen Sulfide
• Process is called
Chemosynthesis
• Often occurs in deep
sea vents or gut of
animals
Called a Black
smoker (thermal
vent)
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Tube Worms living in Black
Smoker
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Consumers
Heterotrophs eat other
organisms to obtain
energy. (e.g. animals)
• Herbivores
– Eat Only Plants
• Carnivores
– Eat Only Other Animals
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Consumers
Heterotrophs eat other organisms
to obtain energy.
• Omnivores (Humans)
– Eat Plants & Animals
• Detritivores (Scavengers)
– Feed On Dead Plant & Animal
Remains (buzzards)
• Decomposers
– Fungi & Bacteria
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Feeding Relationships
Energy flows
through an
ecosystem in
one direction
from producers
to various
levels of
consumers
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Feeding Relationships
• Food Chain
– Simple Energy path through an
ecosystem
• Food Web
– More realistic path through an
ecosystem made of many food
chains
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Food Chain
1st
order
Consumer
2nd Order
Consumer
3rd
Order
consumer
4th Order
Consumer
Producer (trapped
sunlight & stored food)
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Food Chains
• Show who ate who
• Arrow points to where
energy goes
Name the Producer, Consumers
& Decomposers in this food
chain:
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Food Web
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Trophic Levels
Each Level In A Food Chain or Food
Web is a Trophic Level.
• Producers
– Always The First Trophic Level
– How Energy Enters The System
• Herbivores
– Second Trophic Level
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Trophic Levels
• Carnivores/Omnivores
– Make Up The Remaining
Trophic Levels
Each level depends on the
one below it for energy.
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Ecological Pyramids
Graphic Representations Of The
Relative Amounts of Energy or
Matter At Each Trophic Level
May be:
Energy Pyramid
Biomass Pyramid
Pyramid of Numbers
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Energy Pyramid
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Biomass Pyramid
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Pyramid of Numbers
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Energy Pyramid
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Cycling of Nutrients:
Water Cycle
Cycling of Nutrients:
Nitrogen Cycle
Cycling of Nutrients:
Phosphorus Cycle
Cycling of Nutrients
Carbon Cycle
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Population Growth
• How fast do populations grow?
– Starts slow…increases fast
– Exponential growth = “J curve”
– Sigmoid growth = “S curve”
Population Growth
• Will populations keep increasing?
– No! something always runs out
– Called “limiting factors”
• Can you think of any examples?
Population Growth
• Two types of limiting factors:
– Density dependent
• More affected when population is larger
• Examples: food, water, shelter
– Density independent
• Does NOT matter how many are in the
population
• Examples: flood, tornado, etc
Population Growth
• So, how many can live in a habitat?
– Carrying capacity
• # of organisms environment can support
– If population goes above the CC, death rate will increase
Communities
• Communities differ because…
– they have different combinations of biotic & abiotic factors
vary
– Climates differ…so organisms differ
– Organisms are limited by resources available (limiting
factors)
– most organisms can live only within certain range of
conditions (tolerances)
Communities
• Communities change over time because…
– Organisms can change environment so it’s
unsuitable for its continued survival
– The final, stable community is the “climax
community”
Communities
• Succession – change in communities over time
Communities & Biomes
Primary succession
• Happens where life
has never been
before
• Can you think of some
examples?
Secondary succession
• Happens where life
has been before
• Can you think of some
examples?
Biodiversity
• What is BIODIVERSITY?
– Bio = ?
– Diversity = ?
• Important because
– Living things are
interdependent
– Brings stability to ecosystems
– Humans depend on it
Human Impact
• Habitat destruction
– Clear-cutting, development, acid rain, habitat fragmentation
• Ozone depletion
– CFC’s in atmosphere; more UV hitting Earth
• Pollution
– Burning fossil fuels; greenhouse effect
• Threats to biodiversity
– Pollution, habitat loss destroy organisms, exotic species (i.e.
zebra mussels and lampreys)
Habitat Fragmentation
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The End