1. Biology, 9th ed, Sylvia Mader
Chapter 47
Community Ecology
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© B. Runk/S. Schoenberger/Grant Heilman Photography

2. Outline The Concept of the Community The Structure of Communities
Composition and Diversity
Habitat and Ecological Niche
Competition Between Populations
Predator-Prey Interactions
Symbiotic Relationships
Island Biogeography
Community Development
Ecological succession 2

3. Outline The Nature of Ecosystems Energy Flow Biogeochemical Cycles
Abiotic Components
Autotrophs
Heterotrophs
Energy Flow
Ecological Pyramids
Biogeochemical Cycles
Hydrologic Cycle
Carbon Cycle
Nitrogen Cycle
Phosphorus Cycle 3

4. Community Concept
A community is an assemblage of populations interacting with one another within the same environment.
The species composition (also called species richness) of a community is a listing of various species in the community.
Diversity includes both species richness and the abundance of different species.

5. Community Structure a. b.
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squirrel
moose
snowshoe hare
bear
red fox
wolf
kinkajou
monkey
anteater
jaguar
tapir
bat
sloth a. b.
a(Forest): © Charlie Ott/Photo Researchers, Inc.; a(Squirrel): © Stephen Dalton/Photo Researchers, Inc.; a(Wolf): © Renee Lynn/Photo Researchers, Inc.; b(Rain forest): © Michael Graybill and Jan Hodder/Biological Photo Service; b(Kinkajou): © Alan & Sandy Carey/Photo Researchers, Inc.; b(Sloth): © Studio Carlo Dani/Animals Animals Earth Scenes

6. Habitat and Ecological Niche
The area where an organism lives and reproduces
Ecological niche
The role a species plays in its community
Includes its habitat, and
Its interactions with other organisms
Fundamental niche - All conditions under which the organism can survive
Realized niche - Set of conditions under which it exists in nature

7. Feeding Niches for Wading Birds
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Flamingos feed on small molluscs,
crustaceans, and vegetable matter
strained from mud pumped
through their bills by their power-
ful tongues.
Dabbling ducks feed
by tipping, tail up, to
reach aquatic plants,
seeds, snails, and
insects.
Avocets feed on insects, small
marine invertebrates, and seeds
by sweeping their bills from side
to side in shallow water.
Oystercatchers pry open
bivalve shells with their
knifelike bills and probe
sand for worms and crabs.
Plovers dart around
on beaches and
grasslands hunting
for insects and small
invertebrates.

8. Community Structure Competition
When two species compete, the abundance of both species is negatively impacted
Predation (or parasitism)
Expected to increase the abundance of the predator (or parasite)
And reduce the abundance of the prey (or host)

9. Competition Between Populations
Competition occurs when
Members of different species require the same resource, and
The supply of the resource is limited

10. Competition Between Two Laboratory Populations of Paramecium
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P. aurelia grown
separately
Population Density
P. caudatum grown
separately
Population Density
Both species
grown together
Population Density
Time

11. Competition Between Populations
Competitive Exclusion Principle
No two species can indefinitely occupy the same niche at the same time
Resource Partitioning decreases competition between species
Resource partitioning leads to niche specialization and less niche overlap between species
Character Displacement
Characteristics tend to become more divergent when populations belong to the same community than when they are isolated
Competition and resource partitioning may lead to character displacement 11

12. Character Displacement in Finches on the Galápagos Islands
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Species coexist on Abingdon,
Bindloe, James, and Jervis Islands 50
Percent of Sample 30 10
small
medium
Beak Depth
large
G. fortis exists alone
on Daphne Island 50
Percent of Sample 30 10
small
medium
Beak Depth
large
G. fuliginosa exists alone
on Crossman Island 50
Percent of Sample 30 10
small
medium
Beak Depth
large
G. fuliginosa
G. fortis
G. magnirostris

13. Niche Specialization Among Five Species of Coexisting Warblers
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Cape May
warbler
Black-throated
green warbler
Bay-breasted
warbler
Blackburnian
warbler
Yellow-rumped
warbler

14. Competition Between Two Species of Barnacles
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high tide
Chthamalus
area of
competition
Balanus
low tide

15. Predator-Prey Interactions
Predation
One living organism, the predator, feeds on another, the prey
Predator is larger
Predator has lower reproductive rate
Prey usually entirely consumed
Presence of predators can decrease prey densities, and vice-versa

16. Predator-prey Interaction Between a Lynx and a Snowshoe Hare
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140
hare
lynx
120
100 a. 80
Number (thousands) 60 40 20
1845
1855
1865
1875
1885
1895
1905
1915
1925
1935 b.
© Alan Carey/Photo Researchers, Inc.

17. Prey Defenses Prey defenses
Mechanisms that thwart the possibility of being eaten by a predator
Heightened senses
Speed
Protective armor
Protective spines or thorns
Tails or appendages that break off
Poisonous Chemicals
Camouflage
Warning Coloration
Flocking Behavior

18. Anti-predator Defenses
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eye
false head
a. Camouflage
b. Warning colorization
c. Fright
a: © Gustav Verderber/Visuals Unlimited; b: © Zig Leszczynski/Animals Animals/Earth Scenes; c: © National Audubon Society/A. Cosmos Blank/Photo Researchers, Inc.

19. Mimicry
Mimicry
One species resembles another species that possesses an overt antipredator defense
Batesian Mimicry - Mimic lacks defense of the organism it resembles
Müllerian Mimicry - Mimic shares a protective defense with other species

20. Mimicry Among Insects a. Flower fly b. Longhorn beetle c. Bumblebee
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a. Flower fly
b. Longhorn beetle
c. Bumblebee
d. Yellow jacket
a: © Edward S. Ross; b: © Edward S. Ross; c: © James H. Robinson/Photo Researchers, Inc.; d: © Edward S. Ross

21. Symbiotic Relationships
Symbiosis
An association between species in which at least one of the species is dependent on the other

22. Symbiotic Relationships

23. Symbiotic Relationships
Parasitism
Parasite derives nourishment from a host, and may use host as habitat and mode of transmission
Endoparasites
Ectoparasites 23

24. Courtesy the University of Tennessee Parasitology Laboratory
Heartworm
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Courtesy the University of Tennessee Parasitology Laboratory

25. Symbiotic Relationships
Commensalism
A symbiotic relationship in which one species benefits and the other is neither benefited nor harmed
Shark and remora fish
Many supposed examples may turn out to be mutualism or parasitism

26. Clownfish Among Sea Anemone’s Tentacles
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
© Dave B. Fleetham/Visuals Unlimited

27. Symbiotic Relationships
Mutualism
A symbiotic relationship in which both members of the association benefit
Need not be equally beneficial to both species
Cleaning Symbiosis
Often help each other obtain food or avoid predation
Bacteria in human intestinal tract

28. © Bill Wood/Bruce Coleman, Inc.
Cleaning Symbiosis
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© Bill Wood/Bruce Coleman, Inc.

29. Island Biogeography Pertains to Biodiversity
MacArthur and Wilson
Developed a general model of island biogeography
Explains and predicts how the community diversity of an island is affected by
Distance from the mainland, and
Size of the island
The model of island biogeography suggests that the larger the conserved area, the better the chance of preserving more species.

30. Community Development
Ecological Succession
A change involving a series of species replacements following a disturbance
Primary Succession occurs in areas where there is no soil formation
Secondary Succession begins in areas where soil is present
The first species to begin secondary succeession are called pioneer species

31. © Breck P. Kent/Animals Animals/Earth Scene
Secondary Succession
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a. First year
b. Second year
c. Fifth year
d. Tenth year
e. Twentieth year
© Breck P. Kent/Animals Animals/Earth Scene

32. Secondary Succession in a Forest
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grass
low shrub
high shrub
shrub-tree
low tree
high tree

33. Succession Models Facilitation Model
Each stage facilitates invasion and replacement by organisms of the next stage
Succession in a particular area will always lead to the same type of community, a climax community

34. Succession Models Inhibition Model Tolerance Model
Colonists remain and inhibit growth of other plants until the colonists are damaged or die
Tolerance Model
Different types of plants can colonize an area at the same time
Chance determines which seeds arrive first