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Communities
When you describe your community, you
probably include your family, the students in
your school, and the people who live nearby. A
biological
community
is a group of interacting
populations that occupy the same area at the
same time. Therefore, your community also
includes other people, plants, animals, bacteria,
and fungi. Not every community includes the
same variety of organisms. An urban commu-
nity is different from a rural community, and a
desert community is different from a polar
community.
You have learned that organisms living in the
same ecosystem depend on one another for
survival. You also learned about abiotic factors
and how they affect individual organisms.
Recall that limiting factors can influence an
organism’s ability to survive or to reproduce.
How might abiotic factors affect communities?
For example, consider soil, which is an abiotic
factor. If soil becomes too acidic, some species
might die or become extinct. This might affect
food sources for other organisms, resulting in a
change in the community.
Organisms can adapt to the conditions in
which they live. For example, a wolf’s heavy fur
coat enables it to survive in harsh winter
climates, and a cactus’s ability to retain water
enables it to tolerate the dry conditions of a
desert. Depending on which factors are pres-
ent, and to what extent, organisms can survive
in some ecosystems but not in others. For
example, the camel and trees shown in
Figure 1
have adaptations that enable them to thrive in
desert conditions, but would not be useful in
colder climates.
Figure 1
Plants and animals in a desert community have
adaptations to help them survive periods of drought.
FOCUS QUESTION
What is an ecological community?
LESSON 1
COMMUNITY ECOLOGY
Disciplinary Core Ideas
Crosscutting Concepts
Science & Engineering Practices
3D THINKING
C
C
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S
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P
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COLLECT EVIDENCE
Use your Science Journal to
record the evidence you collect as
you complete the readings and
activities in this lesson.
INVESTIGATE
GO ONLINE
to find these activities and more resources.
Applying Practices:
Local Ecosystem Dynamics
HS-LS2-6.
Evaluate the claims, evidence, and reasoning that
the complex interactions in
ecosystems maintain relatively consistent numbers and types of organisms
in stable
conditions,
but changing conditions may result in a new ecosystem.
50
Module 3 • Communities, Biomes, and Ecosystems