1. A. Lizard species perches on
fences and other sunny surfaces.
B. lizard species usually perches
on shady branches.
Resource partitioning is differentiation of ecological niches, enabling similar species to coexist in a community
A. ricordii
Figure 54.2 Resource partitioning among Dominican Republic lizards
A. insolitus
A. aliniger
A. christophei
A. distichus
A. cybotes
A. etheridgei

2. How a species’ niche can be influenced by interspecific competition?
Later - Realized Niche
High tide
Chthamalus
Chthamalus
realized niche
Balanus
Balanus
realized niche
Ocean
Low tide
Ist - Fundamental Niche
High tide
Figure 54.3 Can a species’ niche be influenced by interspecific competition?
Chthamalus
fundamental niche
Ocean
Low tide

3. Character displacement: Indirect Evidence of Past Competition
G. fuliginosa
G. fortis
Beak
depth 60
Los Hermanos 40
G. fuliginosa,
allopatric 20 60
Daphne
Percentages of individuals in each size class 40
G. fortis,
allopatric 20
Figure 54.4 Character displacement: indirect evidence of past competition 60
Santa María, San Cristóbal
Sympatric
populations 40 20 8 10 12 14 16
Beak depth (mm)

4. Müllerian mimicry: Two “yuck”
Cryptic
coloration
Canyon tree frog
(b)
Aposematic
coloration
Poison dart frog
(c) Batesian mimicry: A harmless species mimics a harmful one.
Hawkmoth
larva
Figure 54.5 Examples of defensive coloration in animals
(d)
Müllerian mimicry: Two “yuck”
unpalatable species mimic each other.
Cuckoo bee
Green parrot snake
Yellow jacket

5. A possible example of commensalism between cattle egrets (birds) and water buffalo: The Birds eat insects disturbed by the Buffalo as they move.
Figure 54.8 A possible example of commensalism between cattle egrets and water buffalo

6. Terrestrial and Marine Food Chains
Quaternary
consumers
Carnivore
Carnivore
Tertiary
consumers
Carnivore
Carnivore
Secondary
consumers
Carnivore
Carnivore
Figure Examples of terrestrial and marine food chains
Primary
consumers
Herbivore
Zooplankton
Primary
producers
Plant
Phytoplankton
A terrestrial food chain
A marine food chain

7. An Antarctic Marine Food Web
Humans
Smaller
toothed
whales
Baleen
whales
Sperm
whales
Crab-eater
seals
Leopard
seals
Elephant
seals
Birds
Fishes
Squids
Figure An antarctic marine food web
Carnivorous
plankton
Euphausids
(krill)
Copepods
Phyto-
plankton

8. Seastar are keystone predators
Seastar are keystone predators. They are key in preserving species diversity in their ecosystem.
EXPERIMENT
RESULTS
Figure Is Pisaster ochraceus a keystone predator? 20 15
With Pisaster (control)
Number of species
present 10 5
Without Pisaster (experimental)
1963
’64
’65
’66
’67
’68
’69
’70
’71
’72
’73
Year

9. Sea otters are keystone predators in the North Pacific
100 80
Otter number
(% max. count) 60 40 20
(a) Sea otter abundance
400
300
Grams per
0.25 m2
200
100
(b) Sea urchin biomass
Figure Sea otters as keystone predators in the North Pacific 10 8
Number per
0.25 m2 6 4 2
1972
1985
1989
1993
1997
Year
(c) Total kelp density
Food chain

10. Beavers are a Foundation Species = ecosystem“engineers”
Figure Beavers as ecosystem “engineers”

11. The large-scale fire in Yellowstone National Park in 1988 demonstrated that communities can often respond very rapidly to a massive disturbance.
Figure Recovery following a large-scale disturbance
(a) Soon after fire
(b) One year after fire

12. Pioneer stage = soil builders / fireweed dominant
Figure Glacial retreat and primary succession at Glacier Bay, Alaska 1
Pioneer stage = soil builders / fireweed dominant

13. Dryas stage grasses and shrubs
Figure Glacial retreat and primary succession at Glacier Bay, Alaska 2
Dryas stage grasses and shrubs

14. Alder stage: trees and shrub
Figure Glacial retreat and primary succession at Glacier Bay, Alaska 3
Alder stage: trees and shrub

15. Spruce stage = Climax Community STABLE
Figure Glacial retreat and primary succession at Glacier Bay, Alaska 4
Spruce stage = Climax Community STABLE

16. Changes in soil nitrogen content during succession at Glacier Bay60 50 40
Soil nitrogen (g/m2) 30 20
Figure 54.23 10
Pioneer
Dryas
Alder
Spruce
Successional stage

17. Disturbance of the ocean floor by trawling
Figure Disturbance of the ocean floor by trawling

18. The equilibrium model of island biogeography
Immigration
Extinction
Immigration
Extinction
Immigration
(small island)
(near island)
Extinction
(large island)
(far island)
Extinction
Immigration
Rate of immigration or extinction
Rate of immigration or extinction
(large island)
Rate of immigration or extinction
(far island)
Extinction
Immigration
(near island)
(small island)
Equilibrium number
Small island
Large island
Far island
Near island
Number of species on island
Figure The equilibrium model of island biogeography
Number of species on island
Number of species on island
(a) Immigration and extinction rates
(b) Effect of island size
(c) Effect of distance
from mainland

19. White-band disease on coral is destroying the reef.
Figure 54.29

20. Review

21. You should now be able to:
Distinguish between the following sets of terms: competition, predation, herbivory, symbiosis; fundamental and realized niche; cryptic and aposematic coloration; Batesian mimicry and Müllerian mimicry; parasitism, mutualism, and commensalism; endoparasites and ectoparasites; species richness and relative abundance; food chain and food web; primary and secondary succession.

22. Define an ecological niche and explain the competitive exclusion principle in terms of the niche concept.
Explain how dominant and keystone species exert strong control on community structure.
Distinguish between bottom-up and top-down community organization.
Describe and explain the intermediate disturbance hypothesis.

23. Explain why species richness declines along an equatorial-polar gradient.
Define zoonotic pathogens and explain, with an example, how they may be controlled.