bio_ch14

14.2 Community Interactions
KEY CONCEPT
Organisms interact as individuals and as populations.
14.2 Community Interactions
Competition and predation are two important ways in
which organisms interact.
• Competition occurs when two organisms fight for the
same limited resource.
– Intraspecific
competition
– Interspecific
competition
14.2 Community Interactions
• Predation occurs when one organism captures and eats
another.
14.2 Community Interactions
• There are three major types of symbiotic relationships.
– Mutualism: both organisms benefit
14.2 Community Interactions
• There are three major types of symbiotic relationships.
– Commensalism: one organism benefits, the other is
unharmed
Ø
Human Our eyelashes
are home to tiny mites
that feast on oil
secretions and dead
skin. Without harming
us, up to 20 mites may
be living in one eyelash
follicle.
Commensalism
Ø Organism is not affected
+
+
Organism benefits
Demodicids Eyelash
mites find all they need to
survive in the tiny follicles
of eyelashes. Magnified
here 225 times, these
creatures measure 0.4
mm in length and can be
seen only with a
microscope.
14.2 Community Interactions
• There are three major types of symbiotic relationships.
– Parasitism: one organism benefits, the other is harmed
0
Parasitism
+
_
Hornworm
caterpillar
The host hornworm
will eventually die as
its organs are
consumed
by wasp larvae.
_
Organism is harmed
0
Braconid
wasp
Braconid larvae
feed on their
host and
release
themselves
shortly before
reaching
the pupae
stage of
development.
Organism benefits
14.2 Community Interactions
• There are three major types of symbiotic relationships.
– Parasitism meet their needs as ectoparasites (such
as leeches) and endoparasites (such as hookworms)
14.2 Community Interactions
Two robins eating worms is an example of
A.
B.
C.
D.
Mutualism
Commensalism
Competition
Parasitism
14.2 Community Interactions
Predation is best described as
A. One organism capturing and eating another
B. Two organisms competing for limited resources
C. An interaction in which two species benefit from one
another
D. An interaction in which one species benefits and the
other is not affected
14.2 Community Interactions
Aphids eat the sap from plants and excrete sticky waste
that ants eat. The ants protects the aphids from
predators. This type of interaction is called
A.
B.
C.
D.
Mutualism
Commensalism
Competition
Parasitism
14.2 Community Interactions
An oak tree provides a sparrow a place to build a nest.
The nest neither benefits or harms the tree. What is the
name for this type of relationship?
A. Mutualism
B. Commensalism
C. Competition
D. Parasitism
14.2 Community Interactions
One difference between parasitism and predation is that
parasites
A.
B.
C.
D.
Do very little to harm their hosts
Keep their hosts alive for a period of time
Attack the host only from the inside
Are not very big