Introduction to Ecology
Understanding the World


What affects the environment also affects you.
Understanding what affects the environment is
important because it is where you live. (ie. Global
Warming)
What is Ecology?


Ecology is the study of interactions that take place
between organisms and their environment
Ecology covers the study of plants and animals,
including where they grow and live, what they eat,
or what eats them, is called natural history


All organisms interact
with other organisms in
their surroundings and
with the nonliving part of
their environment
This survival depends on
their interdependence
which is the key term
found throughout
ecology
Interdependence or
Interconnectedness
ANTS AND ACACIA: These ants actually harm acacia trees (Savannah
Africa)in the absence of large herbivores by allowing infestations by other
harmful insects, such as the parasitic scale bugs also pictured here.
Ecological Research

Most ecologists use scientific research includes

using descriptive and quantitative methods
They obtain descriptive information by observing
organisms
Levels of
Organization
1. Most inclusive level of
organization
2. Biosphere is the thin layer of
Earth & its atmosphere that
supports life
3. Extends high in the
atmosphere to bottom of
oceans
4. Supports a diverse group of
organisms in a wide range of
climates
5. All organisms are found
within the biosphere
The Biosphere
Ecosystem
The biosphere is made of smaller units
called ecosystem
 Ecosystems include all of the organisms and
the nonliving environment

Non-living Factors
include:
pH, levels of dissolved
oxygen, carbon dioxide,
& sunlight
Communities

A community is all the interacting
organisms living in an area
Describes all the fish,
plants, algae, bacteria
and other living
organisms found in
this River Ecosystem
Population


A population includes all the
members of a species that
live in one place at the same
time
Members of the same
population may compete
with each other for food,
water, mates, or other
resources.
Represents a population of
California Poppies
Organism

An organism is an individual living thing that is
made possesses all the characteristics of life
Ecosystem Components
Biotic vs. Abiotic

Ecologists separate the environmental
factors that influence an organism into two
types
1. Biotic Factors-all living things that affect an
organism
2. Abiotic Factors-non-living are the physical and
chemical characteristics of an environment
Abiotic Factors
Abiotic factors include temperature,
humidity, pH, salinity, oxygen
concentration, amounts of sunlight,
availability of nitrogen, and precipitation
 Are not constant; vary from place to place
and
over
time
Also important are the small

Amounts of temperature differences
Within a habitat like under a
Shade tree
Organisms in a changed
environment

Each organism is able to survive within a
limited range of environmental conditions
– Example: an organism may be able to function
only within a specific range of temperature. To
determine the range, measure how efficiently it
performs at different temperatures

A graph of performance vs. values of an
environmental variables ie: temperature is
called Tolerance curve
Acclimation of organism
Some organisms can adjust their tolerance to
abiotic factors through the process of
acclimation
Example: goldfish raised at different temperatures
have somewhat different tolerance curves
This occurs within the lifetime of an individual
(different from adaptation)
Environments change in:
Temperature, light, moisture, salinity, and
other chemical factors
 There are 2 ways for organisms to deal with
some of these changes in their environment
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1. Conformers: are organisms that do not regulate
their internal conditions; they change as their
external environment changes
2. Regulators: use energy to control some of their
internal conditions
Control of Internal Conditions

Conformers change their
internal conditions to
what ever the external
environment is.
Conformers are Snakes

Regulators maintain
their internal conditions
constant. Such as as
body temperature, in
humans the normal
body temperature is
98.6
Escape from unsuitable
conditions



Some species can survive unfavorable
environmental conditions by escaping from them
temporarily
A long-term strategy is to enter a state of reduced
activity called dormancy during periods of
unfavorable conditions like winter or drought
Another strategy is to move to a more favorable
habitat called migration
Escape from unsuitable
conditions

dormancy

migration
Niche

A niche is the role or position a
species has in its
environment—how it meets its
specific needs for food and
shelter, how and where it
survives, and where it
reproduces in its environment.

A species’ niche includes all its
interactions with the biotic and
abiotic parts of its habitat
Niches


Generalists are species
with broad niches
They can tolerate a
range of conditions
and use a variety of
resources

Specialists that have a
narrow niche

Generalists: The
Virginia opossum
found across US, feeds
on most anything from
eggs & dead animals
to fruits & plants

Specialists:
The koala of Australia
feeds only on the
leaves of a few species
of eucalyptus trees
Habitat

A habitat is a place an
organism lives out its
life
Nutrition & Energy Flow
Section 2
The Producers: Autotrophs



The ultimate source of the
energy for life is the sun
Plants use the sun’s energy
to manufacture food in a
process called
photosynthesis
An organism that uses
light energy or energy
stored in chemical
compounds to make
energy-rich compounds is
a producer, or autotroph
The Consumer: Heterotrophs


An organism that cannot
make its own food and
feeds on other organisms
is called a Heterotrophs or
consumers
Heterotrophs include:
organisms that feed only
on autotrophs, organisms
that feed only on other
heterotrophs, and
organisms that feed on
both autotrophs and
heterotrophs
Herbivores

Herbivores are
heterotrophs that feed
on only plants
Carnivores

Carnivores are
herbivores that feed on
only meat
American Black Bear
Are carnivores even though they
Feed on berries
Omnivores

Omnivores are
heterotrophs that feed
on both plants and
animals
badger
Scavengers

Scavengers are
herbivores that feed on
animals that have
already died
Decomposers


Some organisms, such as
bacteria and fungi, are
decomposers
Decomposers break down
the complex compounds
of dead and decaying
plants and animals into
simpler molecules that can
be more easily absorbed
Other types of relationships
Symbiosis



The relationship in which there is a close and
permanent association between organisms of
different species is called symbiosis
Symbiosis means living together.
Three kinds of symbiosis are recognized:
1. Mutualism
2. Commensalism
3. Parasitism
Mutualism

Mutualism: is a
symbiotic relationship
in which both species
benefit
Commensalism

Commensalism: is a
symbiotic relationship
in which one species
benefits and the other
species is neither
harmed nor benefited.
Parasitism


Parasitism is a symbiotic
relationship in which a
member of one species
derives benefit at the
expense of another
species (the host)
Parasites have evolved in
such a way that they
harm, but usually do not
kill the host species
Predator vs. Prey

A predator is a type of
consumer. Predators
seek out and eat other
organisms.

Predation is found in
all ecosystems and
includes organisms
that eat plants and
animals

The animals that predators
eat are called prey
Flow of Matter and Energy in Ecosystems
Autotrophs
Third-order
heterotrophs
First-order
heterotrophs
Secondorder
heterotrophs
Decomposer
Food Chain


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A food chain is a simple model that scientists use
to show how matter and energy move through an
ecosystem
In a food chain, nutrients and energy move from
autotrophs to heterotrophs and, eventually, to
decomposers
A food chain is drawn using arrows to indicate the
direction in which energy is transferred from one
organism to the next- uses 3 to 5 links
berries → mice → black bear
Food Chain in an Antarctic
Ecosystem
Trophic Levels


Each organism in a food
chain represents a feeding
step, or trophic level, in
the passage of energy and
materials
A food chain represents
only one possible route for
the transfer of matter and
energy through an
ecosystem
Energy Transfer Through Trophic
Levels
Food Webs

A food web
shows all the
possible feeding
relationships at
each trophic level
in a community
Food Web
in an
Antarctic
Ecosystem
Ecological Food Pyramid


An ecological pyramid can show how energy
flows through an ecosystem
The base of the ecological pyramid represents the
autotrophs, or first trophic level. Higher trophic
levels are layered on top of one another.
The Water Cycle

Steps of the Water Cycle
–
–
–
–
Evaporation
Condensation
Transpiration
Precipitation
The Carbon Cycle
The carbon cycle is the process through which
carbon is cycled through the air, ground, plants,
animals, and fossil fuels.
 Large amounts of carbon exist in the atmosphere
as carbon dioxide (CO2).
 Carbon dioxide is cycled by green plants during
the process known as photosynthesis to make
organic molecules (glucose, which is food).

The Nitrogen Cycle
Nitrogen is used by living organisms to
produce a number of complex organic
molecules like amino acids, proteins, and
nucleic acids.
 The amount of nitrogen found in the
atmosphere, where it exists as a gas (mainly
N2), plays an important role for life.
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