Ecology
• The scientific study of interactions among
organisms and between organisms and their
environment, or surroundings.
• Origin of the word?
Ecology
• The scientific study of interactions among
organisms and between organisms and their
environment, or surroundings.
• Origin of the word?
Greek word – oikos which means ‘house’
Ecology
• The scientific study of interactions among
organisms and between organisms and their
environment, or surroundings.
• Origin of the word?
Greek word – oikos which means ‘house’
therefore – study of nature’s house
Levels of Organization
• Species -
Levels of Organization
• Species – group of organisms so similar to
one another that they can breed and produce
fertile offspring.
• Examples?
Levels of Organization
• Species – group of organisms so similar to
one another that they can breed and produce
fertile offspring.
• Examples?
• Not an example? mules
Levels of Organization
• Population -
Levels of Organization
• Population – groups of individuals that
belong to the same species and live in the
same area
• Examples?
Levels of Organization
• Communities -
Levels of Organization
• Communities – assemblages of different
populations that live together in a defined
area
• Examples?
Levels of Organization
• Ecosystem -
Levels of Organization
• Ecosystem – a collection of all the
organisms that live in a particular place,
together with their nonliving, or physical,
environment
• Examples?
Levels of Organization
• Biome -
Levels of Organization
• Biome – a group of exosystems that have
the same climate and dominant
communities.
• Examples?
Levels of Organization
• Biosphere-
Levels of Organization
• Biosphere –part of Earth in which life exists
including land, water, and air or
atmosphere.
• Example?
Energy Flow
• At the core of every organism’s interaction
with the environment is its need for energy
to power life’s processes.
• What is energy needed for?
Energy Flow
• At the core of every organism’s interaction
with the environment is its need for energy
to power life’s processes.
• What is energy needed for?
– To move
– To make new cells / to grow
– To carry out necessary chemical reactions
Energy Flow
• The main energy source for life on earth is
Energy Flow
• The main energy source for life on earth is
sunlight.
Of all the sun’s energy that reaches Earth’s
surfaces, only a small amount is used by
living things.
Energy Flow
• The main energy source for life on earth is
sunlight.
Of all the sun’s energy that reaches Earth’s
surfaces, only a small amount is used by
living things.
less than 1%
Energy Flow
• Another source of energy for living things is
Energy Flow
• Another source of energy for living things is
inorganic chemical compounds.
Examples?
Energy Flow
• Another source of energy for living things is
inorganic chemical compounds.
Examples?
mineral water that flows underground or
boils out of hot springs and undersea vents
is loaded with chemical energy – sulfer or
nitrogen compounds
Energy Flow
• Autotroph -
Energy Flow
• Autotroph – use energy from the
environment to fuel the assembly of simple
inorganic compounds into complex organic
molecules.
• May also be called?
Energy Flow
• Autotroph – use energy from the
environment to fuel the assembly of simple
inorganic compounds into complex organic
molecules.
• May also be called producers.
• Examples?
Energy Flow
• Autotroph – use energy from the
environment to fuel the assembly of simple
inorganic compounds into complex organic
molecules.
• May also be called producers.
• Examples? Plants, some algae, and certain
bacteria
Energy Flow
• Photosynthesis -
Energy Flow
• Photosynthesis – process where autotrophs
use light energy to power chemical
reactions that convert carbon dioxide and
water into oxygen and energy-rich
carbohydrates such as sugars and starches.
Photosynthesis
• This process is responsible for adding
oxygen to the atmosphere, and also for
removing carbon dioxide from it.
• Chemical equation – page 68, figure 3-5
6 CO2 + 6 H2O 
C6H12O6 + 6 O2
light carbohydrate
energy
Energy Flow
• Chemosynthesis -
Energy Flow
• Chemosynthesis – process where organisms
use chemical energy to produce
carbohydrates
• This process is performed by
Energy Flow
• Chemosynthesis – process where organisms
use chemical energy to produce
carbohydrates
• This process is performed by several types
of bacteria.
Energy Flow
• What is the difference between
photosynthesis and chemosynthesis?
Energy Flow
• Heterotroph -
Energy Flow
• Heterotroph – organisms that rely on other
organisms for their energy and food supply
• They may also be called?
Energy Flow
• Heterotroph – organisms that rely on other
organisms for their energy and food supply
• They may also be called consumers
Types of heterotrophs
• Herbivores -
Types of heterotrophs
• Herbivores – obtain energy by eating only
plants
• Examples?
Types of heterotrophs
• Herbivores – obtain energy by eating only
plants
• Examples? Cows, caterpillars, and deer
Types of heterotrophs
• Carnivores -
Types of heterotrophs
• Carnivores – organisms that obtain energy
by eating animals
• Examples?
Types of heterotrophs
• Carnivores – organisms that obtain energy
by eating animals
• Examples? Snakes, dogs, owls
Types of heterotrophs
• Omnivore -
Types of heterotrophs
• Omnivore – organism that obtains energy
by eating both plants and animals
• Examples?
Types of heterotrophs
• Omnivore – organism that obtains energy
by eating both plants and animals
• Examples? Humans, bears, crows
Types of heterotrophs
• Detrivores -
Types of heterotrophs
• Detrivores – organisms that obtain their
energy by feeding on detritus – plant and
animal remains and other dead matter
• Examples?
Types of heterotrophs
• Detrivores – organisms that obtain their
energy by feeding on detritus – plant and
animal remains and other dead matter
• Examples? Mites, earthworms, snails, crabs
Types of heterotrophs
• Decomposers -
Types of heterotrophs
• Decomposers – organisms that obtain
energy by breaking down organic matter
• Examples?
Types of heterotrophs
• Decomposers – organisms that obtain
energy by breaking down organic matter
• Examples? Bacteria and fungi
Feeding Relationships
• Energy flows through an ecosystem in one
direction,
Feeding Relationships
• Energy flows through an ecosystem in one
direction, from the sun or inorganic
compounds
Feeding Relationships
• Energy flows through an ecosystem in one
direction, from the sun or inorganic
compounds to autotrophs and then to
various heterotrophs
Feeding Relationships
• Food chain -
Feeding Relationships
• Food chain – a series of steps in which
organisms transfer energy by eating and
being eaten.
• Land example?
Feeding Relationships
• Food chain – a series of steps in which
organisms transfer energy by eating and
being eaten.
• Land example?
– Grass > antelope > coyote
• Aquatic example?
Feeding Relationships
• Food chain – a series of steps in which
organisms transfer energy by eating and
being eaten.
• Land example?
– Grass > antelope > coyote
• Aquatic example?
– Algae >zooplankton >small fish >squid >shark
Feeding Relationships
• Food web -
Feeding Relationships
• Food web – network of complex
interactions formed by the feeding
relationships among the various organisms
in an ecosystem
Feeding Relationships
• Trophic levels -
Feeding Relationships
• Trophic levels – each step in a food chain or
food web
• Producers make up the first trophic level
Feeding Relationships
• Trophic levels – each step in a food chain or
food web
• Producers make up the first trophic level
• Consumers make up the second, third, or
higher trophic levels
Feeding Relationships
• Trophic levels – each step in a food chain or
food web
• Producers make up the first trophic level
• Consumers make up the second, third, or
higher trophic levels
• Each consumer depends on the trophic level
below it for energy
Feeding Relationships
Ecological pyramids -
Feeding Relationships
Ecological pyramids – a diagram that shows the
relative amounts of energy or matter contained
within each trophic level in a food chain or
food web.
Feeding Relationships
Ecological pyramids – a diagram that shows the
relative amounts of energy or matter contained
within each trophic level in a food chain or
food web.
Types of ecological pyramids –
Energy
biomass
numbers
Ecological Pyramids
• Energy Pyramid –
– Shows the relative amount of energy available
at each trophic level
– Only about 10% of this energy is used for life
processes
– The rest is lost as heat
Ecological Pyramids
• Biomass Pyramid –
– Represents the amount of living organic matter
at each trophic level
– Typically, the greatest biomass is at the base of
the pyramid
Ecological Pyramids
• Pyramid of Numbers –
– Shows the relative number of individual
organisms at each trophic level
hawk
snakes
rats, mice, and rabbits
grasses and plants