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Chapter 50
An Introduction to Ecology
and the Biosphere
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
What you need to know!
• The role of abiotic factors in the formation of
biomes.
• Features of freshwater and marine biomes.
• Major terrestrial biomes and their
characteristics.
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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
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Ecology – Study of organisms/environment (50.1)
• Ecology
– Has a long history as a descriptive science
– Is also a rigorous experimental science
• The environment of any organism includes
– Abiotic, or nonliving components
– Biotic, or living components
– All the organisms living in the environment, the
biota
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• Environmental components
– Affect the distribution and abundance of
organisms
Kangaroos/km2
> 20
10–20
5–10
1–5
0.1–1
< 0.1
Limits of
distribution
Figure 50.2
Climate in northern Australia
is hot and wet, with seasonal
drought.
Southern Australia has
cool, moist winters and
warm, dry summers.
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Red kangaroos
occur in most
semiarid and arid
regions of the
interior, where
precipitation is
relatively low and
variable from
year to year.
Southeastern Australia
has a wet, cool climate.
Tasmania
Subfields 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?
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• Population ecology
– Concentrates mainly on factors that affect how
many individuals of a particular species live in
an area
(b) Population ecology.
What environmental
factors affect the
reproductive rate of
deer mice?
Figure 50.3b
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• Community ecology
– Deals with the whole array of interacting
species in a community
(c) Community ecology.
What factors influence
the diversity of species
that make up a
particular forest?
Figure 50.3c
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• Ecosystem ecology
– Emphasizes energy flow and chemical cycling
among the various biotic and abiotic
components
(d) Ecosystem ecology. What
factors control photosynthetic
productivity in a temperate
grassland ecosystem?
Figure 50.3d
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• Landscape ecology
– Deals with arrays of ecosystems and how they
are arranged in a geographic region
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?
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• The biosphere
– Is the global ecosystem, the sum of all the
planet’s ecosystems
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Interactions with organisms and environments (50.2)
• Ecologists
– Have long recognized global and regional
patterns of distribution of organisms within the
biosphere
– Some things can limit the distribution of
specific species (like the kangaroos)
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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
– Affected by Biotic and Abiotic Factors
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Natural Range Expansions
• Natural range expansions
– Show the influence of dispersal on distribution
New areas
occupied
Figure 50.7
Year
1996
1989
1974
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Biotic Factors
• Biotic factors that affect the distribution of
organisms may include
– Interactions with other species
– Predation
– Competition
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• A specific case of an herbivore limiting
distribution of a food species
EXPERIMENT
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.
RESULTS
Fletcher observed a large difference in seaweed growth between areas with and without sea urchins.
100
Sea
urchin
Seaweed cover (%)
80
Both limpets
and urchins
removed
Only
urchins
removed
60
Limpet
40
Only limpets removed
Control (both
urchins and
limpets present)
20
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.
0
August
1982
Figure 50.8
February
1983
August
1983
February
1984
CONCLUSION
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.
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Abiotic Factors
• Abiotic factors that affect the distribution of
organisms may include
– Temperature
– Water
– Sunlight
– Wind
– Rocks and soil
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4 Abiotic Factors
make up
Climate
Climate
• Climate - Is the prevailing weather conditions
in a particular area
• 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
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• Sunlight intensity
– Plays a major part in determining the Earth’s
climate patterns
LALITUDINAL VARIATION IN SUNLIGHT INTENSITY
North Pole
60N
Low angle of incoming sunlight
30N
Tropic of
Cancer
Sunlight directly overhead
0 (equator)
Tropic of
Capricorn
30S
Low angle of incoming sunlight
60S
South pole
Figure 50.10
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Atmosphere
SEASONAL VARIATION IN SUNLIGHT INTENSITY
60N
June solstice: Northern
Hemisphere tilts toward
sun; summer begins in
Northern Hemisphere;
winter begins in
Southern Hemisphere.
30N
0 (equator)
March equinox: Equator faces sun directly;
neither pole tilts toward sun; all regions on Earth
experience 12 hours of daylight and 12 hours of
darkness.
30S
Constant tilt
of 23.5
September equinox: Equator faces sun
directly; neither pole tilts toward sun; all
regions on Earth experience 12 hours of
daylight and 12 hours of darkness.
Figure 50.10
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December solstice: Northern
Hemisphere tilts away from sun;
winter begins in Northern
Hemisphere; summer begins
in Southern Hemisphere.
• Air circulation and wind patterns
– Play major parts in determining the Earth’s
climate patterns
GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS
60N
30N
Descending
dry air
absorbs
moisture
0 (equator)
30S
0
60S
Figure 50.10
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Ascending
moist air
releases
moisture
Descending
dry air
absorbs
moisture
Arid
zone
Tropics
Arid
zone
Aquatic Biomes (50.3)
• 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
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• The examination of biomes will begin with
Earth’s aquatic biomes
30N
Tropic of
Cancer
Equator
Tropic of
Capricorn
Continental
shelf
30S
Key
Figure 50.15
Lakes
Rivers
Estuaries
Coral reefs
Oceanic pelagic
zone
Intertidal zone
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Abyssal zone
(below oceanic
pelagic zone)
• 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
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• Many aquatic biomes
– Are stratified into zones or layers defined by
light penetration, temperature, and depth
Intertidal zone
Neritic zone
Littoral
zone
Limnetic
zone
0
Oceanic zone
Photic zone
200 m
Continental
shelf
Pelagic
zone
Benthic
zone
Photic
zone
Aphotic
zone
Pelagic
zone
Benthic
zone
Aphotic
zone
2,500–6,000 m
Abyssal zone
(deepest regions of ocean floor)
(a) Zonation in a lake. The lake environment is generally classified on the basis
of three physical criteria: light penetration (photic and aphotic zones),
distance from shore and water depth (littoral and limnetic zones), and
whether it is open water (pelagic zone) or bottom (benthic zone).
Figure 50.16a, b
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(b) Marine zonation. Like lakes, the marine environment is generally
classified on the basis of light penetration (photic and aphotic zones),
distance from shore and water depth (intertidal, neritic, and oceanic
zones), and whether it is open water (pelagic zone) or bottom (benthic
and abyssal zones).
Vertical Stratification
• Aquatic Biomes = vertical stratification which
forms the following areas:
– Photic zone – where there is enough light for
photosynthesis (aphotic zone – not enough
light for photosynthesis)
– Benthic zone – located at bottom of biome
(made up of sand, inorganic matter, and
organic sediment (detritus))
– Thermoclines – narrow layers of fast temp
change that separates warm upper layer with
cold deeper layer
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Types of Aquatic Biomes
• Freshwater
– Standing bodies of water (lakes and wetlands)
– Moving bodies of water (streams and rivers)
• Marine
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Lakes
• Communities = distributed according to waters
depth
– 2 Zones
• Littoral zone – well lit shallow waters near shore
• Limnetic zone – well-lit open surface waters farther
from shore
– Oligotrophic lakes – deep, nutrient poor,
oxygen rich lakes
– Eutrophic lakes – shallow, high nutrient
content, low oxygen lakes
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• Lakes
LAKES
Figure 50.17
An oligotrophic lake in
Grand Teton, Wyoming
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A eutrophic lake in Okavango
delta, Botswana
• Wetlands
WETLANDS
Figure 50.17
Okefenokee National Wetland Reserve in Georgia
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Streams and Rivers
• Prominent physical attribute = current
• Great diversity of organisms distributed in
vertical zones from headwaters to mouth
• Estuaries – areas where freshwater streams
or rivers merge with the ocean
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• Streams and rivers
STREAMS AND RIVERS
Figure 50.17
A headwater stream in the
Great Smoky Mountains
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The Mississippi River far
form its headwaters
• Estuaries
ESTUARIES
Figure 50.17 An estuary in a low coastal plain of Georgia
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• Intertidal zones
INTERTIDAL ZONES
Figure 50.17
Rocky intertidal zone on the Oregon coast
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Marine Biomes
• Include 2 zones and 2 Biomes:
– Intertizal zones – where land meets water;
periodically submerged and exposed by tides
– Neritic zone – beyond intertidal zone; shallow
water over continental shelves
– Pelagic biome – vast realm of open blue
water found past the continent shelves
– Coral reef – biome created by group of
cnidarians that secrete hard calcium carbonate
shells; among most productive ecosystems on
Earth!
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• Oceanic pelagic biome
OCEANIC PELAGIC BIOME
Figure 50.17 Open ocean off the island of Hawaii
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• Coral reefs
CORAL REEFS
Figure 50.17
A coral reef in the Red Sea
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• Marine benthic zone
MARINE BENTHIC ZONE
Figure 50.17 A deep-sea hydrothermal vent community
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Climate Determines Terrestrial Biomes (50.4)
• Climate
– Is particularly important in determining why
particular terrestrial biomes are found in
certain areas
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Climate and Terrestrial Biomes
• Climate has a great impact on the distribution
of organisms, as seen on a climograph
Temperate grassland
Desert
Tropical forest
Annual mean temperature (ºC)
30
Temperate
broadleaf
forest
15
Coniferous
forest
0
Arctic and
alpine
tundra
15
100
Figure 50.18
200
300
Annual mean precipitation (cm)
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400
• The distribution of major terrestrial biomes
(these are the biomes for your “Biomes Chart”)
30N
Tropic of
Cancer
Equator
Tropic of
Capricorn
30S
Key
Tropical forest
Figure 50.19
Savanna
Desert
Chaparral
Temperate grassland
Temperate broadleaf forest
Coniferous forest
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Tundra
High mountains
Polar ice
Terrestrial Biomes List
• Savannah
• Desert
• Chaparral
• Temperate grassland
• Temperate broadleaf forest
• Coniferous Forest
• Tundra
• Tropical Forest
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• Tropical forest
TROPICAL FOREST
Figure 50.20
A tropical rain forest in Borneo
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• Desert
DESERT
Figure 50.20 The Sonoran Desert in southern Arizona
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• Savanna
SAVANNA
Figure 50.20
A typical savanna in Kenya
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• Chaparral
CHAPARRAL
Figure 50.20
An area of chaparral in California
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• Temperate grassland
TEMPERATE GRASSLAND
Figure 50.20
Sheyenne National Grassland in North Dakota
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• Coniferous forest
CONIFEROUS FOREST
Rocky Mountain National Park in Colorado
Figure 50.20
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• Temperate broadleaf forest
TEMPERATE BROADLEAF FOREST
Figure 50.20
Great Smoky Mountains National Park in North Carolina
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• Tundra
TUNDRA
Figure 50.20
Denali National Park, Alaska, in autumn
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