Table of Contents
Chapter: Ecology
Section 1: What is an ecosystem?
Section 2: Relationships Among
Living Things
Section 3: Energy Through the
Ecosystem
Relationships Among Living Things
2
A. Organizing Ecosystems
1. When ecologists study living things, they
usually start by studying the small groups in
biosphere.
2. To separate the biosphere into smaller
systems that are easier to study, ecologists
find it helpful to organize living things into
groups.
Relationships Among Living Things
2
B. Groups of Organisms
1. A population is a group of the same type of
organisms living in the same place at the
same time.
2. Some populations
that you might
find in a coral reef
ecosystem are
sponges, algae,
sharks, and coral.
Relationships Among Living Things
2
B. Groups of Populations
3. All of the
populations
that live in an
area make up
a community
(kuh MYEW
nuh tee).
4. The members of a community depend on
each other for food, shelter, and other needs.
Relationships Among Living Things
2
C. Characteristics and density
of Populations
1. Ecologists study the characteristics of
populations.
They study the size of the population, where
its members live, and how the population is
able to stay alive.
Relationships Among Living Things
2
C. Characteristics and density
of Populations
2. Population density is the size of the
population compared to its area.
3. For instance, if 100 dandelions are growing
in a field that is one square kilometer in size,
then the population density is 100 dandelions
per square kilometer.
Relationships Among Living Things
2
D. Studying Populations
1. Monarch butterflies travel to warm climates
for the winter. They return to the same place
year after year. This seasonal travel is called
migration.
2. To study migrating monarch butterflies, an
ecologist catches a butterfly and attaches a
tag to one of its wings.
3. Later, someone else who catches the same
butterfly can use the tag to figure out how
far the butterfly has flown.
Relationships Among Living Things
2
D. Studying Populations
4. Information from many butterflies can be
combined to build a picture of the monarch's
migration.
5. Similar techniques
are used to study
populations of birds,
wolves, and other
animals that travel long
distances.
Relationships Among Living Things
2
E. Limits to Populations
1. Populations cannot grow larger and larger
forever. Resources such as food, water, and
living space would eventually run out.
2. The things that limit the size of a population,
such as the amount of rainfall or food, are
called limiting factors.
Relationships Among Living Things
2
E. Limits to Populations
3. In a stream ecosystem, an abiotic limiting
factor might be a lack of rain.
4. If the stream dries up because of lack of rain,
the population of mosquitoes might not have
place to breed. The mosquitoes are a biotic
factor.
5. If the population of mosquitoes goes down,
then the frog population might not have
enough food. This would limit the size of the
frog population.
Relationships Among Living Things
2
F. Interactions in Communities
1. One of the most common ways
organisms interact in a
community is by being food for
another organism, as shown in
the picture.
2. Organisms will compete for any
resource that is in limited supply.
Relationships Among Living Things
2
F. Interactions in Communities
3.The greater the population size of an area,
the greater the competition for resources
such as food.
4. Space, water, sunlight,
and shelter are all
resources that may be
limited in a particular
ecosystem.
Relationships Among Living Things
2
G. Eat or Be Eaten
1. A falcon is a predator (PRE duh tur), which
means it captures and eats other animals. The
animals the falcon catches and eats are its prey.
2. The act of one
organism feeding
on another is
called predation
(pre DAY shun).
Relationships Among Living Things
2
H. Organisms That Live Together
1. There are other types of relationships among
organisms.
2. In one type of interaction, both organisms in
the relationship benefit. For example, an
african tickbird gets its food by eating insects
off the skin of zebras.
Relationships Among Living Things
2
H. Organisms That Live Together
3. The tick birds
gets foods, and the
zebra gets rid of
harmful insects.
http://www.youtube.co
m/watch?v=2D1mu9
WYBNw
Relationships Among Living Things
2
H. Organisms That Live Together
4. In another type of
relationship, only one
organism benefits. For
example, a bird builds a
nest in a tree.
5. The bird gets shelter from
the tree, but the tree is not
harmed.
Relationships Among Living Things
2
H. Organisms That Live Together
6. In still another relationship, one organism is
helped while the other is harmed. Have you ever
been bitten by a mosquito? That's a firsthand
experience of this type of relationship.
Relationships Among Living Things
2
I. Where and How Organisms Live
1. The role of an organism in an ecosystem is
called the organism's niche (NICH). For
example, an aquarium may contain fish,
snails, algae, and bacteria.
2. Each of these organisms has a role in the
aquarium. The snails eat algae to help keep
the glass clear for light to get in.
Relationships Among Living Things
2
I. Where and How Organisms Live
3. The algae provide food for the snails and fish,
and provide oxygen for the system
4. The niche of the fish is to provide nutrients
to the ecosystem through its waste products.
Relationships Among Living Things
2
I. Where and How Organisms Live
5. The place where an organisms lives is called
its habitat (HA buh tat).
The habitat of a
catfish is the muddy
bottom of a lake or pond.
The habitat of penguin
Is the icy waters of the
Antartic.
Relationships Among Living Things
2
I. Where and How Organisms Live
6. Different species of organisms often live in
the same habitat. Resources, such as food, living
space, and shelter, are shared among all the
species living in a habitat.
Relationships Among Living Things
2
I. Where and How Organisms Live
7. For example, Spiders
feed on beetles and other
insects. Caterpillars eat
leaves. Fruit flies feed
on apples. Birds eat
spiders. Caterpillars or
flies. Each species has a
different niche within
the same habitat.
Section Check
2
Question 1
Which represents a population?
A. flock of birds that includes pigeons,
sparrows, and doves
B. forest of trees and all the birds that live in
them
C. group of elephants in Africa and another
group in India
D. group of gray squirrels that live in a park
together
Section Check
2
Question 2
What type of information would you need to
collect concerning the monarch butterfly
population in order to
prepare a map like
this one showing the
migration of
monarchs?
Section Check
2
A. How long
butterflies live
B. what foods
butterflies eat
C. when butterflies
fly through
certain areas
D. when butterflies
lay their eggs
Section Check
2
Question 3
What is the difference between an organism’s
niche and its habitat?
Help
To advance to the next item or next page click on any
of the following keys: mouse, space bar, enter, down or
forward arrow.
Click on this icon to return to the table of contents
Click on this icon to return to the previous slide
Click on this icon to move to the next slide
Click on this icon to open the resources file.
Click on this icon to go to the end of the presentation.
End of Chapter Summary File