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TEXTBOOK
SECTION
3.1,
p.
121
Check
Your
Understanding
Answers
Checking
Concepts
1.
The
development
of
the
two
sticklebacks
in
the
same
lake
was
caused
by
competition
for
food
and
space.
2.
The
role
of
pioneer
species,
such
as
mosses
and
lichens,
is
to
change
the
biotic
and
abiotic
environment,
which
will
then
allow
other
species
to
survive
in
the
ecosystem.
3.
Lichens
are
considered
a
pioneer
species
because
lichens
are
able
to
obtain
nutrients
from
rock
through
chemical
weathering.
Also,
lichens
decay,
adding
to
the
developing
soil.
4.
New
soil
is
created
in
primary
succession
by
the
release
of
nutrients
from
rock
through
chemical
weathering
and
the
decay
of
pioneer
species
plant
material,
which
adds
more
nutrients
to
the
developing
soil.
5.
The
order
is
(d),
(b),
(a),
and
(c).
6.
After
a
volcanic
eruption,
all
the
life
and
previous
soil
will
be
destroyed.
Since
the
cooled
lava
flow
will
be
barren,
this
is
primary
succession.
7.
(a)
Lodgepole
pine
trees
naturally
defend
themselves
against
the
beetle
by
secreting
a
resin,
which
traps
and
flushes
the
adult
beetles
from
the
tree.
(b)
The
mountain
pine
beetle
has
had
such
a
devastating
impact
on
lodgepole
pine
forests
because
cold
temperatures
are
not
being
sustained
long
enough
to
kill
the
beetle
larvae
and
suppression
of
forest
fires
has
retained
large
number
of
older
host
trees
for
the
beetles.
Older
trees
do
not
secrete
as
much
resin
to
defend
against
the
beetle.
8.
There
are
more
types
of
species
in
a
forest
undergoing
succession
because
there
is
less
light
available
in
a
mature
forest
so
there
is
less
of
a
variety
of
plant
species
and
therefore
fewer
different
habitats
for
animals.
Understanding
Key
Ideas
9.
Darwin’s
finches
illustrate
adaptive
radiation
since
changes
in
some
finches
allowed
them
to
adapt
to
particular
niches
and
food
sources.
The
individuals
that
were
best
adapted
survived
and
reproduced
and
that
is
natural
selection.
10.
Sample
answer:
bare
rock
→
mosses
and
lichens
→
nutrients
available
→
decay
→
more
3.1
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WKBK
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soil
→
new
species
of
plants
established
→
animals
move
in
→
abiotic
and
biotic
conditions
continue
to
change
→
mature
community
11.
(a)
There
is
no
soil
available
in
primary
succession
initially,
but
there
is
soil
available
in
secondary
succession.
(b)
There
are
no
nutrients
available
initially
in
primary
succession,
but
there
are
existing
nutrients
in
secondary
succession.
(c)
Secondary
succession
may
take
decades.
Primary
succession
takes
centuries.
13.
The
scenario
should
show
a
progression
from
grass
to
small
trees
and
bushes
to
a
forest.
14.
Flooding
affects
ecosystems,
causing
soil
erosion
and
pollution.
Harmful
bacteria
may
be
carried
in
flood
water
and
cause
disease.
Prolonged
drought
destroys
habitats,
killing
animals
and
plants.
Insect
infestations
can
destroy
forests
and
the
habitats
for
animals.
WORKBOOK:
Section
3.1
How
Changes
Occur
Naturally
in
Ecosystems
Change
in
ecosystems
Page
40
1.
natural
selection
2.
adaptive
radiation
3.
ecological
succession
4.
primary
succession
5.
pioneer
species
6.
climax
community
7.
secondary
succession
8.
flooding
9.
tsunami
10.
drought
11.
insect
infestations
Analyzing
Information
Primary
and
secondary
succession
Page
41
1.
Answer
should
include
the
following
sequence:
•
Lichens
begin
to
grow.
This
begins
the
process
of
soil
formation.
•
Plants,
such
as
mosses,
begin
to
grow.
•
Insects,
micro‐organisms,
and
other
organisms
move
in.
•
Grasses,
wildflowers,
and
shrubs
begin
to
grow.
More
insects
and
micro‐organisms
move
in.
•
Tree
seeds
are
transported
by
animals.
Deciduous
trees
grow.
•
Coniferous
trees
germinate.
•
Mature
community
develops.
2.
Answer
should
include
the
following
sequence:
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•
Exposed
soil
will
contain
micro‐organisms,
worms,
and
insects
as
well
as
the
seeds
of
wildflowers,
weeds,
grasses,
and
trees.
•
Other
seeds
may
blow
in
or
be
carried
in
by
animals.
•
Deciduous
trees
grow.
•
Coniferous
trees
return.
•
Mature
community
may
only
take
decades
to
establish.
Applying
Knowledge
How
natural
events
affect
ecosystems
Page
42
NATURAL
EVENT
EFFECTS
ON
MATURE
COMMUNITY
•
causes
secondary
succession
•
results
in
regrowth
•
causes
soil
erosion
•
results
in
soil
and
water
pollution,
leading
to
widespread
disease
•
water
carries
away
or
destroys
plants
and
animals
•
disrupts
habitats
and
foods
webs
•
salt
from
salt
water
changes
composition
of
soil
•
destroys
habitats
•
results
in
the
death
of
plants
and
animals
•
leads
to
crop
failures
and
livestock
deaths
•
results
in
losses
to
forest
canopy
•
disrupts
habitats
and
food
webs
FIRE
FLOODING
TSUNAMI
DROUGHT
INSECT
INFESTATION
Assessment
How
changes
occur
naturally
in
ecosystems
Page
43
1.
B
2.
A
3.
D
4.
E
5.
C
6.
C
7.
D
8.
C
9.
B
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