1. Chapter 53
Community Ecology

2. I. Interspecific Interactions
Competition
Competitive exclusion principle
Niche – fundamental vs. realized
Resource partitioning
Character displacement
Predation
Adaptations
Cryptic coloration
Aposemetic coloration
Mimicry

3. Table 53-1

4. LE 53-2
High tide
High tide
Chthamalus
Chthamalus
realized niche
Balanus
Chthamalus
fundamental niche
Balanus
realized niche
Ocean
Ocean
Low tide
Low tide

5. A. insolitus usually perches on shady branches. A. ricordii
LE 53-3
A. insolitus
usually perches
on shady branches.
A. ricordii
A. distichus
perches on
fence posts
and other
sunny
surfaces.
A. insolitus
A. aliniger
A. christophei
A. distichus
A. cybotes
A. etheridgei

6. Santa María, San Cristóbal
LE 53-4
G. fortis
G. fuliginosa
Beak
depth
Santa María, San Cristóbal 40
Sympatric
populations 20
Los Hermanos
Percentage of individuals in each size class 40
G. fuliginosa,
allopatric 20
Daphne 40
G. fortis,
allopatric 20 8 10 12 14 16
Beak depth (mm)

7. Figure 53-05

8. Figure 53-06

9. LE 53-7
Green parrot snake
Hawkmoth larva

10. LE 53-8
Cuckoo bee
Yellow jacket

11. Herbivory Parasitism Disease - pathogens Mutualism Commensalism
Endoparasites, ectoparasites and parasitoidism
Disease - pathogens
Mutualism
Commensalism

12. II. Dominant and Keystone Species and Control of Community
Species diversity
Species richness
Relative abundance
Trophic structure
Food webs (Fig )
Limits on length
Energetic hypothesis
Dynamic stability hypothesis

13. LE 53-11 A B C D
Community 1
A: 25%
B: 25%
C: 25%
D: 25%
Community 2
A: 80%
B: 5%
C: 5%
D: 10%

14. A terrestrial food chain
LE 53-12
Quaternary
consumers
Carnivore
Carnivore
Tertiary
consumers
Carnivore
Carnivore
Secondary
consumers
Carnivore
Carnivore
Primary
consumers
Herbivore
Zooplankton
Primary
producers
Plant
Phytoplankton
A terrestrial food chain
A marine food chain

15. LE 53-13 Humans Smaller toothed whales Baleen whales Sperm whales
Crab-eater
seals
Leopard
seals
Elephant
seals
Birds
Fishes
Squids
Carnivorous
plankton
Euphausids
(krill)
Copepods
Phyto-
plankton

16. Sea nettle Juvenile striped bass Fish larvae Fish eggs Zooplankton

17. Number of trophic links
LE 53-15 6 6
No. of species 5 5
No. of trophic
links 4 4
Number of species
Number of trophic links 3 3 2 2 1 1
High
(control)
Medium
Low
Productivity

18. Species with a Large Impact
Dominant species
Keystone species (Fig , p. 1168)
Foundation species
Bottom-Up and Top-Down Controls
Bottom-Up: NVHP
Nutrients are limiting factors
Top-Down: NVHP
Predation is limiting factor

19. LE 53-16 With Pisaster (control) 20 15 Number of species present
Without Pisaster (experimental) 10 5
1963
’64
’65
’66
’67
’68
’69
’70
’71
’72
’73

20. LE 53-17 100 80 Otter number (% max. count) 60 40 20
Sea otter abundance
400
300
Grams per
0.25 m2
200
100
Sea urchin biomass 10 8
Number per
0.25 m2 6 4 2
1972
1985
1989
1993
1997
Year
Total kelp density
Food chain before
killer whale
involvement in
chain
Food chain after
killer whales started
preying on otters

21. Figure 53-18

22. With Juncus Without Juncus
LE 53-19 8 6
Number of plant species 4 2
With
Juncus
Without
Juncus
Salt marsh with Juncus
(foreground)
Conditions

23. herbaceous plant cover
LE 53-20
100 75
herbaceous plant cover
Percentage of 50 25
100
200
300
400
Rainfall (mm)

24. Polluted State Restored State Fish Abundant Rare Zooplankton Rare
LE 53-UN1171
Polluted State
Restored State
Fish
Abundant
Rare
Zooplankton
Rare
Abundant
Algae
Abundant
Rare

25. III. Disturbance Influences Communities
Definition and causes
Changes in community and removal of species
Human roles
Ecological succession
Primary
Secondary

26. 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.

27. 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.

28. LE 53-24 Pioneer stage, with fireweed dominant Dryas stage Spruce60 50 40
Soil nitrogen (g/m2) 30 20 10
Pioneer
Dryas
Alder
Spruce
Successional stage
Spruce
stage
Nitrogen fixation by Dryas and alder
increases the soil nitrogen content.

29. IV. Biogeographic Factors on Community
Equatorial-Polar gradients
Area effects
Species-area curve (p. 1176)
Island equilibrium model
Size and distance from mainland
Immigration/extinction

30. LE 53-25 180 160 140 120 Tree species richness 100 80 60 40 20 100 300
100
300
500
700
900
1,100
Actual evapotranspiration (mm/yr)
Trees
200
100
Vertebrate species richness
(log scale) 50 10
500
1,000
1,500
2,000
Potential evapotranspiration (mm/yr)
Vertebrates

31. Number of species (log scale)
1,000
100
Number of species (log scale) 10 1 1 10
100
103
104
105
106
107
108
109
1010
Area (acres)

32. LE 53-27 Immigration Immigration Extinction Immigration Extinction
(small island)
(near island)
Extinction
(large island)
(far island)
Extinction
Immigration
(far island)
Rate of immigration or extinction
Immigration
(large island)
Rate of immigration or extinction
Extinction
Rate of immigration or extinction
(near island)
(small island)
Equilibrium
number
Small
island
Large
island
Far
island
Near
island
Number of species on island
Number of species on island
Number of species on island
Immigration and extinction rates
Effect of island size
Effect of distance from mainland

33. 0.1 1 10 100 1,000 Area of island (mi2) (log scale)
400
200
100 50
Number of plant species (log scale) 25 10 5
0.1 1 10
100
1,000
Area of island (mi2)
(log scale)

34. V. Views of Community Structure
Integrated hypothesis
Individualistic hypothesis

35. LE 53-29 Population densities of individual species
Environmental gradient
(such as temperature or moisture)
Integrated hypothesis
Population
densities of
individual
species
Environmental gradient
(such as temperature or moisture)
Individualistic hypothesis
Number of
per hectare
plants
600
400
200
Wet
Moisture gradient
Dry
Trees in the Santa Catalina Mountains