1. Chapter 52
An Introduction to Ecology and the
Biosphere

2. Overview: The Scope of Ecology
• Ecology
– Is the scientific study of the interactions between
organisms and the environment
• These interactions
– Determine both the distribution of organisms and
their abundance
– Is an enormously complex and exciting area of
biology
– Reveals the richness of the biosphere

3. Sub-fields of Ecology
• Organismal ecology
– Studies how an organism’s structure,
physiology, and (for animals) behavior meet the
challenges posed by the environment
Figure 50.3a
(a) Organismal ecology. How do humpback whales
select their calving areas?

4. • Population ecology
_ Population: groups of same species in the same
area.
– Concentrates mainly on factors that affect how many
individuals of a particular species live in an area
Figure 50.3b
Population ecology.
What environmental
factors affect the
reproductive rate of
deer mice?
(b)

5. • Community ecology
- Community: all the organisms in one particular
area.
– Deals with the whole array of interacting species in a
community
Figure 50.3c
(c) Community ecology.
What factors influence
the diversity of species
that make up a
particular forest?

6. • Ecosystem ecology
- all the abiotic factors in addition to the entire
commuity of species in a certain area.
– Emphasizes energy flow and chemical cycling among
the various biotic and abiotic components
Figure 50.3d
(d) Ecosystem ecology. What
factors control photosynthetic
productivity in a temperate
grassland ecosystem?

7. • Landscape ecology
– Deals with arrays of ecosystems and how they are
arranged in a geographic region
– Focuses on the factors controlling exchanges of
energy, materials, and organisms among the
ecosystem patches making up a landscape or seacape
Figure 50.3e
(e) Landscape ecology. To what extent do the trees lining the
drainage channels in this landscape serve as corridors of
dispersal for forest animals?

8. • The biosphere
– Is the global ecosystem, the sum of all the planet’s
ecosystems
– Ex: How CO2 concentration affect the climate and all
life on Earth.
– Global ecology examines the influence of energy and
materials on organisms across the biosphere

9. Concept 52.1: Ecology integrates all
areas of biological research and
informs environmental decision
making
• Ecology has a long history as a descriptive science
• It is also a rigorous experimental science

10. Fig. 52-3
Trough
Pipe
“Dry” “Wet” “Ambient”
Studying how a forest responds to
altered precipitation

11. Ecology and Environmental Issues
• Ecology
– Provides the scientific understanding underlying
environmental issues
• Rachel Carson
– Is credited
with starting
the modern
environmental
movement
– Silent Spring, 1962
– DDT Figure 50.4

12. Ecology and Evolutionary Biology
• Events that occur in ecological time
– Affect life on the scale of evolutionary time
– Therefore, ecology and evolutionary biology are
closely related sciences.
– Ex: haws deeding on field mice causing
– Immediately effect: Reducing of the size of the mice
population and altering the gene pool
– Long-term effect: predator-prey interaction may be
selected for mice with fur coloration that
camouflages the animals.

13. Concept 52.2: Interactions between
organisms and the environment limit
the distribution of species
• Ecologists have long recognized global and regional
patterns of distribution of organisms within the
biosphere.
• Biogeography is a good starting point for
understanding what limits geographic distribution
of species.
• Ecologists recognize two kinds of factors that
determine distribution: biotic, or living factors, and
abiotic, or nonliving factors.

14. Fig. 52-5
Kangaroos/km2
0–0.1
0.1–1
1–5
5–10
10–20
> 20
Limits of
distribution

15. Fig. 52-6
Why is species X absent
from an area?
Does dispersal
limit its
distribution?
Does behavior
limit its
distribution?
Area inaccessible
or insufficient time
Yes
No
No
No
Yes
Yes
Habitat selection
Do biotic factors
(other species)
limit its
distribution?
Predation, parasitism,
competition, disease
Do abiotic factors
limit its
distribution?
Chemical
factors
Physical
factors
Water
Oxygen
Salinity
pH
Soil nutrients, etc.
Temperature
Light
Soil structure
Fire
Moisture, etc.
• Ecologists consider multiple factors when
attempting to explain the distribution of species

16. • Concept 50.2: Interactions between organisms
and the environment limit the distribution of
species
• Ecologists
– Have long recognized global and regional patterns of
distribution of organisms within the biosphere

17. Dispersal and Distribution
• Dispersal
– Is the movement of individuals away from
centers of high population density or from their
area of origin
– Contributes to the global distribution of
organisms

18. Fig. 52-7
Current
1966
1970
1965 1960
1961
1958
1951
1943
1937
1956
1970
Natural Range Expansions
Dispersal of the cattle egret in the Americas

19. Species Transplants
• Species transplants
– Include organisms that are intentionally or
accidentally relocated from their original distribution
– Can often disrupt the communities or ecosystems to
which they have been introduced
– To be successful in species transplants, the organism
must not only survive in the new area but also
reproduce there.

20. Behavior and Habitat Selection
• Some organisms
– Do not occupy all of their potential range
• Species distribution
– May be limited by habitat selection behavior
– Example: larvae of the European corn borer
– Example: mosquito habitats

21. Biotic Factors
• Biotic factors that affect the distribution of
organisms may include
– Interactions with other species
– Predation
– Competition

22. A specific case of an herbivore
limiting distribution of a food species
• Seaweed
distribution
Figure 52.8
W. J. Fletcher tested the effects of two algae-eating animals, sea urchins and limpets, on seaweed
abundance near Sydney, Australia. In areas adjacent to a control site, either the urchins, the limpets, or both were removed.
EXPERIMENT
RESULTS Fletcher observed a large difference in seaweed growth between areas with and without sea urchins.
100
80
60
40
20
0
Limpet
Sea
urchin Both limpets
and urchins
removed
Only
urchins
removed
Only limpets removed
August
1982
February
1983
August
1983
February
1984
Control (both
urchins and
limpets present)
Seaweedcover(%)
Removing both
limpets and
urchins or
removing only
urchins increased
seaweed cover
dramatically.
Almost no
seaweed grew
in areas where
both urchins and
limpets were
present, or where
only limpets were
removed.
Removing both limpets and urchins resulted in the greatest increase of seaweed cover, indicating that both
species have some influence on seaweed distribution. But since removing only urchins greatly increased seaweed growth while
removing only limpets had little effect, Fletcher concluded that sea urchins have a much greater effect than limpets in limiting
seaweed distribution.
CONCLUSION

23. Biotic Factors for Limiting
Distribution
• Predation
• Herbivory
• Food sources
• Parasites
• Pathogens
• Competing organisms

24. Abiotic Factors
• Abiotic factors that affect the distribution of
organisms may include
– Temperature
– Water
– Sunlight
– Wind
– Rocks and soil

25. Climate
• Four major abiotic components make up climate
– Temperature, water, sunlight, and wind
• Climate
– Is the prevailing weather conditions in a particular
area

26. Classification of Climate Factors
• Climate patterns can be described on two scales
– Macroclimate, patterns on the global, regional, and
local level
– Microclimate, very fine patterns, such as those
encountered by the community of organisms
underneath a fallen log

27. Global Climate Patterns
• Earth’s global climate patterns
– Are determined largely by the input of solar
energy and the planet’s movement in space

28. Regional, Local, and Seasonal
Effects on Climate
• Various features of the landscape
– Contribute to local variations in climate

29. Microclimate
• Microclimate
– Is determined by fine-scale differences in abiotic factors

30. Long-Term Climate Change
• One way to predict future global climate change
– Is to look back at the changes that occurred
previously
Figure 52.14
Current
range
Predicted
range
Overlap
(a) 4.5C warming over
next century
(b) 6.5C warming over
next century

31. • Concept 50.3: Abiotic and biotic factors
influence the structure and dynamics of aquatic
biomes
• Varying combinations of both biotic and abiotic
factors
– Determine the nature of Earth’s many biomes
• Biomes
– Are the major types of ecological associations that
occupy broad geographic regions of land or water

32. • The examination of biomes will begin with
Earth’s aquatic biomes
Figure 52.15
30N
Tropic of
Cancer
Equator
30S
Continental
shelf
Lakes
Coral reefs
Rivers
Oceanic pelagic
zone
Estuaries
Intertidal zone
Abyssal zone
(below oceanic
pelagic zone)
Key
Tropic of
Capricorn

33. • Aquatic biomes
– Account for the largest part of the biosphere in
terms of area
– Can contain fresh or salt water
• Oceans
– Cover about 75% of Earth’s surface
– Have an enormous impact on the biosphere

34. • Concept 50.4: Climate largely determines the
distribution and structure of terrestrial biomes
• Climate
– Is particularly important in determining why
particular terrestrial biomes are found in certain
areas

35. General Features of Terrestrial
Biomes
• Terrestrial biomes
– Are often named for major physical or climatic
factors and for their predominant vegetation
• Stratification
– Is an important feature of terrestrial biomes

36. The distribution of major terrestrial
biomes
30N
Tropic of
Cancer
Equator
Tropic of
Capricorn
30S
Key
Tropical forest
Savanna
Desert
Chaparral
Temperate grassland
Temperate broadleaf forest
Coniferous forest
Tundra
High mountains
Polar iceFigure 50.19

37. Climate and Terrestrial Biomes
• Climate has a great impact on the distribution of
organisms, as seen on a climograph
Figure 50.18
Desert Temperate grassland Tropical forest
Temperate
broadleaf
forest
Coniferous
forest
Arctic and
alpine
tundra
Annual mean precipitation (cm)
Annualmeantemperature(ºC)
100 200 300 400
30
15
0
15