Biology 1
Chapter 18
Introduction to Ecology
Do Now
A
fight between a family of lions and
family of hyenas over an animal carcass
would be best described as competition
between




A.
B.
C.
D.
two different populations.
a population and a community.
two different communities.
a community and an ecosystem.
Introduction to Ecology
 Ecology-the
study of the interactions
between organisms and the living and
nonliving components of their
environment.
 Interdependence-organisms affect and
are affected by other organisms in their
surroundings and by the nonliving parts of
their environment
Interdependence
 Examples
of interdependence
Levels of Organization
 Biosphere-the
thin volume of Earth and its
atmosphere that supports life


All organisms are found within the
biosphere
Extends 5-6 miles above the
Earth and to the deepest
parts of the Ocean.
Levels of Organization
 Ecosystem-all
of the organisms and the
non-living environment found in a
particular place.

Ex. Pond
Levels of Organization
 Community-all
the interacting organisms
living in an area.
Levels of Organization
 Population-all
of the members of a
species that live in one place at one time.
 Species-a group of organisms that can
mate and produce fertile offspring.
Ecosystem Components
 Biotic
Factors-all of the living things that
affect an organism
 Abiotic Factors-all of the physical and
chemical characteristics of the
environment.

Temperature, humidity,
pH, salinity, oxygen
concentration, amount
of sunlight, availability
of nitrogen, precipitation.
Organisms in a Changing
Environment
 Each
organism is able to survive within a
limited range of environmental conditions.
 Tolerance Curve-a graph of performance
versus values of an environmental
variable.
 Acclimation-organisms
adjust their
tolerance to abiotic factors.

Occurs within the lifetime of an individual
 Adaption-genetic
change in a species or
population that occurs from generation to
generation over time.
 Conformer-organisms
that do not
regulation their internal conditions;
change as their external environment
changes; ectothermic.
 Regulator-organisms that use energy to
control some of their internal conditions;
keep an internal condition within the
optimal range; endothermic.
 Dormancy-a
longer-term strategy of
entering a state of reduced activity.
 Migration-moving to a more favorable
habitat
Do Now

The amount of life that can be supported in a
particular ecosystem is limited by which of the
following?
I.
energy
II.
water
III.
minerals
IV.
oxygen

A.
B.
C.
D.



II and IV only
I, II, III, and IV
I and II only
II, III, and IV only
• Look at the organisms in the image above. Which of the
following organisms are most closely related
evolutionarily?
•
A.
fish and clam
•
B.
fish and starfish
•
C.
starfish and sand dollar
•
D.
crab and starfish
The Niche
 Niche-the
specific role, or way of life, of a
species within its environment.
 Generalist-species with broad niches; can
tolerate a range of conditions and use a
variety of resources.
 Specialist-species that have a narrow
niche
Producers
 Producer-produce
their own food;
autotrophs.
 Photosynthesis-organisms use light to
produce food.
 Chemosynthesis-organisms use energy
stored in inorganic molecules to produce
food.
Measuring Productivity
 Gross
primary productivity-the rate at which
producers in an ecosystem capture the energy of
sunlight by producing organic compounds.
 Biomass-the organic material that has been
produced in an ecosystem.
 Net primary productivity-the rate at which biomass
accumulates.

Net primary productivity=Gross primary productivity – rate of respiration
Consumers




Consumer-obtain energy by consuming organic
molecules made by other organisms; heterotrophs
Herbivores-eat producers; primary consumer; 10
Carnivores-eat other consumers; secondary
consumer; 20
Omnivores-eat produces and consumers
Consumers
 Detritivore-consumes
that feed on the
“garbage” of an ecosystem
 Detritus-organisms that have recently
died, fallen leaves, and animal wastes
 Decomposer-break down complex
molecules into simpler molecules
 Make the nutrients that were contained in
detritus available again to the autotrophs
in the ecosystem.
 Food
Web Quick Draw
 Food Web How Stuff Works
 Food Web Discovery Channel
Do Now

Chemicals can affect an ecosystem. Which
of the following is a result of pesticide
application?

A. Pesticide application improves soil fertility,
increasing the diversity of plants in the
ecosystem.
B. Pesticide kills all kinds of insects, including
predatory insects, which in turn can increase
the population of insects for which the
pesticide was intended.
C. Pesticide application does not affect
ecosystems. This is why it is widely used on
farms and ranches.
D. It always leaves a residue on plant leaves,
reducing photosynthesis.




Answer: B
• Nearly all mammals have seven cervical (neck)
vertebrae. This fact implies that
• A. all animals can turn their heads the same
amount.
• B. predators prefer to eat animals with either six
or eight cervical vertebrae.
• C. all mammals have to stretch their necks to
obtain food.
• D. all mammals descended from a common
ancestor.
• The figure above shows the progression of embryonic
stages of four species of invertebrates. Which of the
following species are most closely related by evolution?
•
A.
Species A and Species D
•
B.
Species A and Species B
•
C.
Species C and Species D
•
D.
Species B and Species C
•
SABER TOOTH TIGER PRESENT DAY TIGER
• The skeletons of a saber tooth tiger and a present-day
tiger are shown above. Which of the following is a
structural difference between the saber tooth and the
present-day tiger?
•
A.
size of scapulae
•
B.
shape and size of skull
•
C.
size of teeth
•
D.
all of these
Energy Flow
 When
one organism eats another,
molecules are metabolized and energy is
transferred; heat is lost as a waste product.
 Trophic Level-indicates the organism’s
position in a sequence of energy transfers
 First Trophic Level-Producers
 Second Trophic Level-Consumers
 Third Trophic Level-Predators
Food Chain
 Food
chain-a single pathway of feeding
relationships among organisms in an
ecosystem that results in energy transfer.
Food Web
 Food
Web-Interrelated food chains in an
ecosystem.
Do Now

A rodent population in a forest ecosystem contains every
member of that species. These rodents eat a variety of
plants and live in hardwood trees. Their population growth
is limited by the amount of space they have available.

Human construction in the area is steadily reducing the
habitat of the rodent species. Which of the following will
most likely occur if the species' habitat continues to be
destroyed?

A. The species will experience population growth.
B. The limiting factor of the population will change.
C. The population will use less resources and stay the
same size.
D. The species will eventually go extinct.
Answer: D




Ecosystem Recycling
 Water
cycle-the movement of water
between various reservoirs.
 Cells contain 70-90% water, and water
provides the environment in which most of
life’s chemical reactions occur.
 Groundwater-water in the soil or in
underground formations of porous rock


Evaporation-adds water as vapor to the
atmosphere.
Transpiration-the process by which water
evaporates from the leaves of plants in
terrestrial ecosystems


Causes plants to take in water through their
roots and to replace the water that is being lost
through their leaves.
Precipitation-water leaving the atmosphere
Water Cycle
Carbon Cycle






Carbon Cycle-photosynthesis and cellular
respiration
In photosynthesis, autotrophs use carbon
dioxide, water, and solar energy to make
carbohydrates (glucose).
Heterotrophs use oxygen to break down
carbohydrates during cellular respiration.
The byproducts of cellular respiration are
carbon dioxide and water.
Decomposers release carbon dioxide into the
atmosphere when they break down organic
compounds
Crash Course-Water and Carbon Cycles
Carbon Cycle
Human Influence
 Fossil
Fuels-remains of organisms that have
been transformed by decay, heat, and
pressure into energy-rich molecules.

Coal, oil, natural gas
 Burning
fossil fuels releases the energy in
these molecules, but it also releases
carbon dioxide.
 Excessive carbon dioxide in the
atmosphere leads to a warming effect
(greenhouse effect).
Nitrogen Cycle






All organisms need nitrogen to make proteins
and nucleic acids.
Nitrogen fixation-the process of converting
nitrogen gas to nitrate.
Nitrogen-fixing bacteria-bacteria who
transform nitrogen gas into a usable form
Ammonification-Decomposers break down
urine and dung and release the nitrogen they
contain as ammonia (NH3), which in the soil
becomes ammouium (NH4+).
Nitrification-Soil bacteria takes up ammonium
and oxidizes it into nitrites and nitrates.
Denitrification-nitrogen is returned to the
atmosphere.
Nitrogen Cycle
Phosphorous Cycle




Phosphorous is an element that is used to form
bones, teeth, and parts of molecules, such as
DNA & RNA.
Phosphorous Cycle-the movement of
phosphorus from the environment to
organisms and then back to the environment.
When rocks erode, small amounts of
phosphorous dissolve in soil & water and then
plants absorb phosphorous in the soil.
Crash Course-Nitrogen and Phosphorous
Cycle
Phosphorous Cycle
 Crash
Course