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Unformatted text preview: 4/24/09
 Lec
80.
Community
Ecology
 Mark
A.
Sarvary
 BioG
1102
Final
Exam,
2
‐
4:30
PM,
May
7
 Two
parts:
 1)  coverage
from
the
last
prelim
(22
%,
same
as
another
prelim)
 2)  comprehensive,
from
lecture
42
‐
83
(10
%) All
questions
will
be
multiple
choice
(no
essays)
 The
comprehensive
section
will
test
general
principles,
not
details.
 Example
cumulative
question
for
the
final
 Three
metabolic
enzymes
are
responsible
for
breaking
down
the
sugar
arabinose
to
 D‐xyluose‐5‐phosphate.
The
genes
for
these
enzymes
are
linked
on
the
same
 chromosome
and
are
regulated
by
a
common
promoter.

Which
statement
about
 these
enzymes
and
their
genes
is
INCORRECT?
 A)
an
operator
is
associated
with
the
promoter
 B)
the
second
gene
consists
of
four
exons
and
three
introns
 C)
the
second
structural
gene
codes
for
the
first
enzyme
in
the
pathway
 D)
arabinose
activates
the
pathway
 E)
transcription
is
catalyzed
by
RNA
polymerase
 Dr.
Sarvary
will
not
have
office
hours
today
 Fig. 52-2 Organismal
 ecology
 Population
Dynamics
 •  interactions
between
biotic
and
abiotic
factors
that
 cause
variation
in
population
size
 Abiotic
‐‐
weather
 Biotic
‐‐
predation
 Population
 ecology
 Community
 ecology
 Ecosystem
 ecology
 Landscape
 ecology
 Global
 ecology
 1
 4/24/09
 Population
Dynamics
 •  Lynx
populations
follow
the
10
year
boom‐and‐bust
 cycle
of
hare
populations

 Human
population
dynamics
 Delayed
response
of
the
predator
 •  No
population
can
grow
indefinitely,
and
humans
 are
no
exception
 Human
population
dynamics
 Regional
Patterns
of
Population
Change
 •  To
maintain
population
stability,
a
regional
human
 population
can
exist
in
one
of
two
configurations:
 –  Zero
population
growth
=

 High
birth
rate
–
High
death
rate
 –  Zero
population
growth
=
 Low
birth
rate
–
Low
death
rate
 •  The
demographic
transition
is
the
move
from
the
 first
state
toward
the
second
state
 •  No
population
can
grow
indefinitely,
and
humans
 are
no
exception
 •  The
demographic
transition
is
associated
with
an
 increase
in
the
quality
of
health
care
and
improved
 access
to
education
 Natural
selection

Life
History
 Trade‐off
 2
 4/24/09
 Global
Carrying
Capacity
 •  How
many
humans
can
the
biosphere
support?
 Global
Carrying
Capacity
 The
ecological
footprint
concept
summarizes
the
 aggregate
land
and
water
area
needed
to
sustain
the
 people
of
a
nation
 Use
of
photosynthetic
products
 Sustainable:
Productive
land/population
size=
2
ha/person
 USA:
10
ha
ecological
footprint
per
capita
 Global
Carrying
Capacity
 



Nonrenewable
 resources

 Meat
consumption
 Universal
carrying
capacity
 Water
 Waste
 The
Great
Pacific
Garbage
Patch,
also
 described
as
the
Eastern
Garbage
 Patch
or
the
Pacific
Trash
Vortex,
is
a
 gyre
of
marine
debris
in
the
central
 North
Pacific
Ocean
located
roughly
 between
135°
to
155°W
and
35°
to
 42°N.

 Earth
dynamics
 •  http://www.breathingearth.net/
 dN
 =
 r N
 dt
 max •  http://www.breathingearth.net/
 Earth
dynamics
 3
 4/24/09
 Per
capita
(individual)
rate
of
increase
 •  •  •  •  •  There
are
300
million
people
in
the
USA
 In
1
hour
9000
people
were
born
and
4000
died.
 In
1
year
an
estimated:
79.5
mill
people
are
born
 In
1
year
an
estimated:
35.3
mill
people
die
 The
US
can
handle
500
million
people
 •  •  •  •  •  If
Δt=
1
yr

 N=
300mill
Americans
 B=

79.5
mill

offspring
 b=

79.5
mill/300mill=0.265
(annual
per
capita
birth
rate)
 d=35.3
mill/300mill=0.117
(annual
per
capita
death
rate)
 •  •  •  •  •  r=
per
capita
rate
of
increase
 r=
0.148
 r
<
0

declining
population
 r
>
0
growing
population
 r=
0
Zero
population
growth
 ΔN
 =
 0.148*300mill=44.4mill
 Δt
 Net
population
annual
growth=
 •  r=
per
capita
rate
of
increase
 •  r=
0.265‐0.117=0.148
 Net
population
annual
growth=
 ΔN
 =
 0.148*300mill=44.4mill
 Δt
 Net
population
annual
growth=
 ΔN
 =
 0.148*300mill=44.4mill
 Δt
 If
r(max)
=
1.0

 If
there
is
44.4mill
net
population
growth
in
the
USA,
is
the
 USA
experiencing

exponential
growth?
 If
r(max)
=
1.0

 If
there
is
44.4mill
net
population
growth
in
the
USA,
is
the
 USA
experiencing

exponential
growth?
 A,
No
 B,
Yes
 C,
I
have
no
clue
 *
A,
No
 B,
Yes
 C,
I
have
no
clue
 No,
because
it ’s
per
capita
rate
of
increase
does
not
equal
its
maximum
rate….
 •  •  •  •  •  There
are
300
million
people
in
the
USA
 In
1
hour
9000
people
were
born
and
4000
died.
 In
1
year
:
79.5
mill
people
are
born
 In
1
year
:
35.3
mill
people
die
 The
US
can
handle
500
million
people
 In
the
logistic
population
growth
model,
 the
per
capita
rate
of
increase
declines
as
 carrying
capacity
is
reached
 dN=(
300mill+(79.5m‐35.3m))‐300mill
 (200mill)
 44.2mill
 
 = r*300mill*
 500mill
 1
yr
 r=44.2/120=0.368
 (K
‐
N)
 dN
 =
 dt
 rmax
N
 K
 Number
of
additional
 Individuals
the
habitat
 can
support
 4
 4/24/09
 Lec
80.
Community
Ecology
 Mark
A.
Sarvary
 Community
ecology
 •  A
biological
community
is
an
assemblage
of
 populations
of
various
species
living
close
 enough
for
potential
interaction
 •  Number
of
species
 •  Which
species
are
present
 •  Relative
abundance
of
species
 •  Interactions
between
species
 Interspecific
interactions
 •  Ecologists
call
relationships
between
species
in
a
 community
interspecific
interactions
 •  Interspecific
interactions
can
affect
the
survival
 and
reproduction
of
each
species,
and
the
 effects
can
be
summarized
as
positive
(+),
 negative
(–),
or
no
effect
(0)
 Competition
 •  Interspecific
competition
(–/–
interaction)
 occurs
when
species
compete
for
a
resource
in
 short
supply
 Can
two
species
coexist
in
the
same
habitat?

 Competitive
Exclusion
 –  two
species
competing
for
the
 same
limiting
resources
cannot
 coexist
in
the
same
place
 The
ecological
niche:
the
total
of
an
organism’s
use
of
the
biotic
and
 
 
 
 
 
 
abiotic
resources
in
its
environment
 Can
two
species
coexist
in
the
same
habitat?

 5
 4/24/09
 Can
two
species
coexist
in
the
same
habitat?

 The
ecological
niche:
the
total
of
an
organism’s
use
of
the
biotic
and
 
 
 
 
 
 
abiotic
resources
in
its
environment
 Natural
selection

Resource
Partitioning
 •  the
differentiation
of
niches
 A.
insolitus
 usually
perches
 on
shady
branches.
 A.
ricordii
 Realized
niche
 A.
distichus
perches
on 
 fence
posts
and
other 
 sunny
surfaces. 
 A.
alinigar
 A.
distichus
 A.
insolitus
 A.
christophei
 A.
cybotes
 A.
etheridgei
 Fundamental
niche:
occupies
in
absence
of
competitors
 Natural
selection

Character
displacement
 Predation
 •  Predation
(+/–
interaction)
refers
to
interaction
 where
one
species,
the
predator,
kills
and
eats
 the
other,
the
prey
 Allopatric
 Sympatric
 Predator
 •  Feeds on more than one host per lifecycle… PREDATOR Predation
 6
 4/24/09
 Excluding
predators
in
ecological
 experiments….
 Natural
selection

Defense
against
predation
 •  •  •  •  Cryptic
coloration
 Aposematic
coloration
 Batesian
Mimicry
 Müllerian
Mimicry
 Cryptic
Coloration
 Aposematic
Coloration
 Batesian
mimicry
 •  Batesian
Mimicry:
A
palatable
or
harmless
 species
mimics
an
unpalatable
or
harmful
 model
 Batesian
mimicry
 Müllerian
Mimicry
 •  Müllerian
Mimicry:
Two
or
more
unpalatable
 species
resemble
each
other
 (b)
Green
parrot
snake
 (a)
Hawkmoth
larva
 7
 4/24/09
 Herbivory
 •  the
process
in
which
an
herbivore
eats
parts
of
 a
plant
 –  evolution
of
plant
mechanical
and
chemical
 defenses
and
consequent
adaptations
by
 herbivores
Dr.
Kessler ’s
lecture
 Symbiosis
 •  Symbiosis
is
a
relationship
where
two
or
more
 species
live
in
direct
and
intimate
contact
with
 one
another
 Definition
varies
from
ecologist
to
ecologist…..
 Parasitism
 •  In
parasitism
(+/–
interaction),
one
organism,
the
 parasite,
derives
nourishment
from
another
organism,
 its
host,
which
is
harmed
in
the
process
 •  Parasites
that
live
within
the
body
of
their
host
are
 called
endoparasites;
parasites
that
live
on
the
external
 surface
of
a
host
are
ectoparasites
 Parasitism
 •  More than 1 species is in the same host… •  Always kills the host… Parasitism
 •  Some
parasites
change
the
behavior
of
the
host
 to
increase
their
own
fitness
   Parasite: •  The host survives… parasitized
aphids
 that
contain
 diapausing
 parasitoid
larvae
 leave
the
host
 plant
to
mummify
 in
concealed
sites

   Aphids parasitized by non-diapausing parasitoids remain on the leaf Parasitized larvae showed negative phototaxis caused by the need of dormant parasitoids overwintering in sheltered sites 8
 4/24/09
 Mutualism
 Cardinal
vs.
Cowbird
 •  Mutualistic
symbiosis,
or
mutualism
(+/+
 interaction),
is
an
interspecific
interaction
that
 benefits
both
species
 
 A
mutualism
can
be
 Obligate,
where
one
species
cannot
 survive
without
the
other
(Termites‐ Trychonimpha)
 Nest‐parasite
 Facultative,
where
both
species
 can
survive
alone
 (Plants‐Mycorrhizal
fungi)
 Commensalism
 •  In
commensalism
(+/0
interaction),
one
species
 benefits
and
the
other
is
apparently
unaffected
 •  Commensal
interactions
are
hard
to
document
 in
nature
because
any
close
association
likely
 affects
both
species
 Fig.
54‐9
 Species
Diversity
 •  Species
richness
is
the
total
number
of
different
 species
in
the
community
 •  Relative
abundance
is
the
proportion
each
 species
in
the
community
 – Shannon
diversity
index
(H):
 H
=
–[(pA
ln
pA)
+
(pB
ln
pB)
+
(pC
ln
pC)
+
…]
 A
 B
 C
 D
 Community
1
 A:
25%

B:
25%

C:
25%

D:
25%
 Community
2
 A:
80%

B:
5%

C:
5%

D:
10%
 



Dwarf
mistletoes
are
flowering
plants
that
grow
on
certain
 forest
trees,
using
one
tree
during
their
life
cycle.
They
 obtain
nutrients
and
water
from
the
vascular
tissues
of
the
 trees.
The
trees
derive
no
known
benefits
from
the
dwarf
 mistletoes.
Which
of
the
following
best
describes
the
 interactions
between
dwarf
mistletoes
and
trees?

 
 
 
 
 
 A)
parasitism
 B)
mutualism
 C)
commensalism

 D)
predation

 E)
competition
 



Dwarf
mistletoes
are
flowering
plants
that
grow
on
certain
 forest
trees,
using
one
tree
during
their
life
cycle.
They
 obtain
nutrients
and
water
from
the
vascular
tissues
of
the
 trees.
The
trees
derive
no
known
benefits
from
the
dwarf
 mistletoes.
Which
of
the
following
best
describes
the
 interactions
between
dwarf
mistletoes
and
trees?

 



A)
parasitism
 *
 
 B)
mutualism
 
 C)
commensalism

 
 D)
predation

 
 E)
competition
 9
 4/24/09
 Trophic
Structure
 •  Trophic
structure
is
the
feeding
relationships
 between
organisms
in
a
community‐>Food
 chains
 Fig.
54‐12
 Humans
 Baleen
 whales
 Smaller
 toothed
 whales
 Sperm
 whales
 Crab‐eater
 seals
 Leopard
 seals
 Elephant
 seals
 Birds
 Fishes
 Squids
 Carnivorous
 plankton
 Euphausids
 (krill)
 Copepods
 Phyto‐
 plankton
 Dominant
Species
 •  Dominant
species
are
those
that
are
most
 abundant
or
have
the
highest
biomass
 •  Dominant
species
exert
powerful
control
over
 the
occurrence
and
distribution
of
other
species
 Central NY Dominant
parasitoid

family
 Western NY Dominant predator families Keystone
Species
 •  Keystone
species
exert
strong
control
on
a
 community
by
their
ecological
roles,
or
niches
 •  In
contrast
to
dominant
species,
they
are
not
 necessarily
abundant
in
a
community
 10
 4/24/09
 Foundation
Species
(Ecosystem
“Engineers”)
 •  Foundation
species
(ecosystem
“engineers”)
 cause
physical
changes
in
the
environment
that
 affect
community
structure
 Bottom‐Up
and
Top‐Down
Controls
 •  The
bottom‐up
model
of
 community
organization
 proposes
a
unidirectional
 influence
from
lower
to
 higher
trophic
levels
 •  The
top‐down
model,
also
 called
the
trophic
cascade
 model,
proposes
that
control
 comes
from
the
trophic
level
 above
 Bottom‐Up
and
Top‐Down
Controls
 •  Longer
development
of
primary
consumers
may
 increase
their
mortality
(slow‐growth‐high‐mortality
 hypothesis).
Top
down.
 •  Parasitoids
and
predators
are
expected
to
be
found
 more
abundant
in
diverse
habitats
(Natural
Enemy
 Hypothesis
(Root,
1973)
Bottom
up
 •  The
resource
concentration
hypothesis
(Root
1973)
 predicts
that
specialist
herbivorous
insects
should
be
 more
abundant
in
large
patches
of
host
plants,
 because
the
insects
are
more
likely
to
find
and
stay
 longer
in
those
patches.
Bottom
up


 Disturbance
 •  Disturbance
influences
species
diversity
and
 composition
 –  Historically,
ecologists
thought
communities
are
in
 equilibrium
 •  Intermediate
Disturbance
Hypothesis
 –  moderate
levels
of
disturbance
can
foster
higher
 species
diversity
than
low
levels
of
disturbance
 Fire
in
Yellowstone
National
Park
in
1988
 Ecological
Succession
 •  Ecological
succession
is
the
sequence
of
 community
and
ecosystem
changes
after
a
 disturbance
 •  Primary
succession
occurs
where
no
soil
exists
 when
succession
begins
 •  Secondary
succession
begins
in
an
area
where
 soil
remains
after
a
disturbance
 Succession:
sequence
of
community
and
ecosystem
changes
 after
a
disturbance
 11
 4/24/09
 Ecological
Succession
 •  Early‐arriving
species
and
later‐arriving
species
 may
be
linked
in
one
of
three
processes:
 –  Early
arrivals
may
facilitate
appearance
of
later
 species
by
making
the
environment
favorable
 –  They
may
inhibit
establishment
of
later
species
 –  They
may
tolerate
later
species
but
have
no
impact
 on
their
establishment
 Area
Effects
 •  The
species‐area
curve
quantifies
the
idea
that,
 all
other
factors
being
equal,
a
larger
geographic
 area
has
more
species
 Fig.
54‐27a
 Rate
of
immigration
or
extinction
 •  Species
richness
on
 island
depends
on
 –  island
size
 –  distance
from
the
 mainland
 •  immigration
 •  extinction
 near far dispersal •  MacArthur
and
Wilson
 ‐
1960
 Source region (large land mass) Equilibrium
number
 Number
of
species
on
island
 (a)
Immigration
and
extinction
rates
 Fig.
54‐27b
 Fig.
54‐27c
 Rate
of
immigration
or
extinction
 Rate
of
immigration
or
extinction
 Ex (sm tinc all tion 
is 
 lan d) 
 (sm Im al ig ra l
is tion 
 la nd )
 m Ex ti (l 
is ge ar t nc io n
 l d an )
 Im m (fa igr r
i ati sla on nd 
 )
 Small
island
 (b)
Effect
of
island
size
 Large
island
 Far
island
 Number
of
species
on
island
 Number
of
species
on
island
 (c)
Effect
of
distance
from
mainland
 Ex (fa tinc r
i tio sla n
 nd )
 Ex 
 on cti d)
 tin slan Ex r
i ea (n Near
island
 tin cti o n
 Island
Equilibrium
Model
 Im m 
 ion at igr n
 tio 
 gra and) mi l Im ar
is (ne n
 io )
 at igr land m s Im ge
i r (la 12
 4/24/09
 Which
island
has
the
lowest
number
of
species?
 Which
island
has
the
lowest
number
of
species?
 *
 13
 ...
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This note was uploaded on 10/20/2009 for the course BIO G 1102 taught by Professor Walcott during the Spring '08 term at Cornell.

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