chapter 53 community ecology. i. interspecific interactions competition –competitive exclusion...
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Chapter 53Chapter 53
Community EcologyCommunity Ecology
I. Interspecific InteractionsI. Interspecific Interactions
CompetitionCompetition– Competitive exclusion principleCompetitive exclusion principle– Niche – fundamental vs. realizedNiche – fundamental vs. realized– Resource partitioningResource partitioning– Character displacementCharacter displacement
PredationPredation– AdaptationsAdaptations
Cryptic colorationCryptic coloration
Aposemetic colorationAposemetic coloration
MimicryMimicry
Table 53-1
LE 53-2
Chthamalusfundamental niche
High tide
Low tideOcean
Chthamalusrealized niche
High tide
Low tideOcean
Balanusrealized niche
Chthamalus
Balanus
LE 53-3A. insolitususually percheson shady branches.
A. ricordii
A. insolitus
A. christophei
A. cybotes
A. etheridgei
A. alinigerA. distichus
A. distichusperches onfence postsand othersunnysurfaces.
LE 53-4
Beakdepth
Sympatricpopulations
G. fuliginosaG. fortis
Santa María, San Cristóbal
40
20
0
Los Hermanos
40
20
0
Daphne
40
20
0
G. fuliginosa,allopatric
G. fortis,allopatric
Beak depth (mm)
161412108
Pe
rce
nta
ge
of
ind
ivid
ua
ls i
n e
ac
h s
ize
cla
ss
Figure 53-05
Figure 53-06
LE 53-7
Hawkmoth larva
Green parrot snake
LE 53-8
Cuckoo bee
Yellow jacket
HerbivoryHerbivory
ParasitismParasitism– Endoparasites, ectoparasites and Endoparasites, ectoparasites and
parasitoidismparasitoidism
Disease - pathogensDisease - pathogens
MutualismMutualism
CommensalismCommensalism
II. Dominant and Keystone Species II. Dominant and Keystone Species and Control of Communityand Control of Community
Species diversitySpecies diversity– Species richnessSpecies richness– Relative abundanceRelative abundance
Trophic structureTrophic structure– Food webs (Fig. 53.13)Food webs (Fig. 53.13)– Limits on lengthLimits on length
Energetic hypothesisEnergetic hypothesis
Dynamic stability hypothesisDynamic stability hypothesis
LE 53-11
Community 1
AB
C
D
A: 25% B: 25% C: 25% D: 25%
Community 2A: 80% B: 5% C: 5% D: 10%
LE 53-12
Quaternaryconsumers
Tertiaryconsumers
Carnivore
Carnivore
Carnivore
Carnivore
Secondaryconsumers
CarnivoreCarnivore
Primaryconsumers
ZooplanktonHerbivore
Primaryproducers
PhytoplanktonPlant
A terrestrial food chain A marine food chain
LE 53-13
Euphausids(krill)
Carnivorousplankton
Phyto-plankton
Copepods
Squids
Elephantseals
FishesBirds
Crab-eaterseals
Leopardseals
Spermwhales
Smallertoothedwhales
Baleenwhales
Humans
LE 53-14
Zooplankton
Fish larvae
Fish eggs
Sea nettle Juvenile striped bass
LE 53-15
Productivity
Nu
mb
er o
f tr
op
hic
lin
ks
Nu
mb
er o
f sp
ecie
s
No. of trophiclinks
No. of species
High(control)
6
5
4
3
2
1
0
6
5
4
3
2
1
0Medium Low
Species with a Large ImpactSpecies with a Large Impact– Dominant speciesDominant species– Keystone species (Fig. 53.16, p. 1168)Keystone species (Fig. 53.16, p. 1168)– Foundation speciesFoundation species
Bottom-Up and Top-Down ControlsBottom-Up and Top-Down Controls– Bottom-Up: NBottom-Up: NVVHHPP
Nutrients are limiting factorsNutrients are limiting factors
– Top-Down: NTop-Down: NVVHHPPPredation is limiting factorPredation is limiting factor
LE 53-16
Without Pisaster (experimental)
With Pisaster (control)
1963 ’64 ’65 ’66 ’67 ’68 ’69 ’70 ’71 ’72 ’73
20
15
10
5
0
Nu
mb
er
of
sp
ec
ies
pre
se
nt
LE 53-17
100
80
60
40
0
20
Sea otter abundance
Ott
er
nu
mb
er
(% m
ax
. c
ou
nt)
400
300
200
0
100
Sea urchin biomass
Gra
ms
pe
r0
.25
m2
10864
02
Total kelp density
Nu
mb
er
pe
r0
.25
m2
19971993198919851972Year
Food chain beforekiller whaleinvolvement inchain
Food chain afterkiller whales startedpreying on otters
Figure 53-18
LE 53-19
Nu
mb
er o
f p
lan
t sp
ecie
s
8
6
4
0
2
Conditions
WithJuncus
WithoutJuncusSalt marsh with Juncus
(foreground)
LE 53-20
Per
cen
tag
e o
fh
erb
aceo
us
pla
nt
cove
r100
75
50
0
25
Rainfall (mm)
200 300 4000 100
LE 53-UN1171
Polluted State Restored State
Fish Abundant Rare
Zooplankton AbundantRare
Algae Abundant Rare
III. Disturbance Influences III. Disturbance Influences CommunitiesCommunities
Definition and causesDefinition and causes– Changes in community and removal of Changes in community and removal of
speciesspecies– Human rolesHuman roles
Ecological successionEcological succession– PrimaryPrimary– SecondarySecondary
LE 53-21
Before a controlled burn.A prairie that has not burned for several years has a high propor-tion of detritus (dead grass).
During the burn. The detritus serves as fuel for fires.
After the burn. Approximately one month after the controlled burn, virtually all of the biomass in this prairie is living.
LE 53-22
Soon after fire. As this photo taken soon after the fire shows, the burn left a patchy landscape. Note the unburned trees in the distance.
One year after fire. This photo of the same general area taken the following year indicates how rapidly the com-munity began to recover. A variety of herbaceous plants, different from those in the former forest, cover the ground.
LE 53-24Pioneer stage, with fireweed dominant
Dryas stage
Spruce stageNitrogen fixation by Dryas and alder
increases the soil nitrogen content.
Successional stage
DryasPioneer Alder Spruce
So
il n
itro
gen
(g
/m2)
60
50
40
30
20
10
0
IV. Biogeographic Factors on IV. Biogeographic Factors on CommunityCommunity
Equatorial-Polar gradientsEquatorial-Polar gradients
Area effectsArea effects– Species-area curve (p. 1176)Species-area curve (p. 1176)
Island equilibrium modelIsland equilibrium model– Size and distance from mainlandSize and distance from mainland– Immigration/extinctionImmigration/extinction
LE 53-25
Trees
Tre
e sp
ecie
s ri
chn
ess
180
160
140
120
100
80
0
Ver
teb
rate
sp
ecie
s ri
chn
ess
(lo
g s
cale
)
200
100
50
10
60
40
20
1,100900700500300100Actual evapotranspiration (mm/yr)
Vertebrates
2,000Potential evapotranspiration (mm/yr)
1,5001,000500
LE 53-26
Nu
mb
er o
f sp
ecie
s (l
og
sca
le)
1,000
Area (acres)
1010109106 107 108103 104 1051 10 100
100
10
1
LE 53-27
Immigration and extinction rates
Number of species on island
Equilibriumnumber
Imm
igration
Rat
e o
f im
mig
rati
on
or
exti
nct
ion
Extin
ctio
n
Effect of island size
Number of species on island
Smallisland
Imm
igration
Rat
e o
f im
mig
rati
on
or
exti
nct
ion
Extin
ctio
n
Largeisland
(large island)
Imm
igration
(small island)
Extin
ctio
n
(larg
e is
land)
(sm
all i
slan
d)
Effect of distance from mainland
Number of species on island
Farisland
Imm
igration
Rat
e o
f im
mig
rati
on
or
exti
nct
ion
Extin
ctio
n
Nearisland
(near island)
Imm
igration
(far island) Extinctio
n
(near i
sland)
(far i
slan
d)
LE 53-28
Area of island (mi2)(log scale)
400N
um
ber
of
pla
nt
spec
ies
(lo
g s
cale
)
1,0001001010.1
200
100
50
25
10
5
V. Views of Community StructureV. Views of Community Structure
Integrated hypothesisIntegrated hypothesis
Individualistic hypothesisIndividualistic hypothesis
LE 53-29
Trees in the Santa Catalina Mountains
Nu
mb
er
of
pla
nts
pe
r h
ec
tare
Moisture gradientWet
600
400
200
0
Environmental gradient(such as temperature or moisture)
Po
pu
lati
on
de
ns
itie
s o
fin
div
idu
al
sp
ec
ies
Individualistic hypothesis
Environmental gradient(such as temperature or moisture)
Po
pu
lati
on
de
ns
itie
s o
fin
div
idu
al
sp
ec
ies
Integrated hypothesis
Dry
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