Competition Among Living
•Explore how living things
Vocabulary: compete for things they need.
•competition •Explain why competition
occurs in ecosystems.
•niche Explain how populations avoid
How Much Room Do
• Competition for space affects how plants
grow. Competition occurs when one
organism works against another to get
what it needs to live. Organisms may
compete for space, water, food, or
some other need.
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compete for water.
A cactus soaks up
all the moisture in
a single area. No
other plants can
grow in this area.
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Rabbits compete for food. If there are too
many rabbits, all of the grass will be eaten.
Some of the rabbits won’t survive.
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Different ecosystems support different numbers
of organisms. The chart below compares the
numbers of different types of birds in a rain
forest with those in a temperate forest.
Different Types of Different Types of
Temperate Forest 50-60 50
Rain Forest 500-600 250
Temperate forests are the most common type of
forest in the U.S. Rain forests support many more
types of trees and birds than temperate forests.
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The same pattern is true for other
living things. Why are there so
many more types of organisms in
the rain forest? Rain forests are
much wetter and warmer than
temperate forests. More plants can
grow in this environment. More
plants means more animals, too.
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Can Competition Be Avoided?
Competition is a struggle for
survival. In order to survive, some
organisms find ways to avoid
competing. Many types of
organisms share the same
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Each type of organism has its own
niche. A niche is the job or role an
organism has in an ecosystem. An
organism’s niche includes what an
organism does, what it eats, and
how it interacts with other
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For example, there are many types of pigeons in
the forests of New Guinea. Each type has a
different niche. This helps the pigeons avoid
competition. The Victoria crowned pigeon has a
niche that includes eating fruits, berries, and large
seeds. The pigeon nests in trees and searches for
food on the ground of the forest.
The forests of New
Guinea are home to
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Why It Matters
As a living thing, you have a niche in
your ecosystem. Your niche
includes the roles you have at
home and at school. How is your
niche different from the niches of
other people and animals in the
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