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Transcript of 50 Ecology Intro Text
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Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Chapter 50Chapter 50
An Introduction to Ecology
and the Biosphere
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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
Is an enormously complex and exciting area ofbiology
Reveals the richness of the biosphere
Figure 50.1
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Concept 50.1: Ecology is the study of
interactions between organisms and theenvironment
Ecology
Has a long history as a descriptive science
Is also a rigorous experimental science
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Organisms and the Environment
The environment of any organism includes
Abiotic, or nonliving components
Biotic, or living components
All the organisms living in the environment, thebiota
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Environmental components
Affect the distribution and abundance oforganisms
Figure 50.2
Kangaroos/km2
> 20
1020
510
15
0.11
< 0.1
Limits of
distribution
Climate in northern Australia
is hot and wet, with seasonal
drought.
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.Southern Australia has
cool, moist winters and
warm, dry summers.Tasmania
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Ecologists
Use observations and experiments to testexplanations for the distribution and
abundance of species
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Subfields of Ecology
Organismal ecology
Studies how an organisms 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 howmany 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)
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Community ecology
Deals with the whole array of interactingspecies in a community
Figure 50.3c
(c) Community ecology.
What factors influence
the diversity of species
that make up a
particular forest?
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Ecosystem ecology
Emphasizes energy flow and chemical cyclingamong the various biotic and abiotic
components
Figure 50.3d
(d) Ecosystem ecology. What
factors control photosynthetic
productivity in a temperate
grassland ecosystem?
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Landscape ecology
Deals with arrays of ecosystems and how theyare 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 theplanets ecosystems
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Ecology and Environmental Issues
Ecology
Provides the scientific understandingunderlying environmental issues
Rachel Carson
Is credited
with starting
the modern
environmentalmovement
Figure 50.4
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Most ecologists follow the precautionary
principle regarding environmental issues The precautionary principle
Basically states that humans need to be
concerned with how their actions affect theenvironment
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Concept 50.2: Interactions between organisms
and the environment limit the distribution ofspecies
Ecologists
Have long recognized global and regional
patterns of distribution of organisms within the
biosphere
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Many naturalists
Began to identify broad patterns of distributionby naming biogeographic realms
Tropic
of Cancer
(23.5N)
Equator
Nearctic
Neotropical
Ethiopian
Oriental
Australian
Palearctic
(23.5S)
Tropic of
CapricornFigure 50.5
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Biogeography
Provides a good starting point forunderstanding what limits the geographic
distribution of species
Figure 50.6
Species absent
because
Yes
No
Dispersal
limits
distribution?Behavior
limits
distribution?
Biotic factors
(other species)
limit
distribution?
Abiotic factors
limit
distribution?
Yes
No
Yes
No
Area inaccessible
or insufficient time
Habitat selectionPredation, parasitism,
competition, diseaseWater
Oxygen
Salinity
pHSoil nutrients, etc.
Temperature
Light
Soil structure
Fire
Moisture, etc.
Chemical
factors
Physical
factors
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Dispersal and Distribution
Dispersal
Is the movement of individuals away fromcenters of high population density or from their
area of origin
Contributes to the global distribution oforganisms
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New areas
occupied Year
1996
1989
1974
Natural Range Expansions
Natural range expansions
Show the influence of dispersal on distribution
Figure 50.7
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Species Transplants
Species transplants
Include organisms that are intentionally oraccidentally relocated from their original
distribution
Can often disrupt the communities orecosystems to which they have been
introduced
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Behavior and Habitat Selection
Some organisms
Do not occupy all of their potential range
Species distribution
May be limited by habitat selection behavior
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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
Figure 50.8
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 andlimpets 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 whereonly 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
A i i
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Abiotic Factors
Abiotic factors that affect the distribution of
organisms may include
Temperature
Water
Sunlight
Wind
Rocks and soil
T
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Temperature
Environmental temperature
Is an important factor in the distribution oforganisms because of its effects on biological
processes
W
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Water
Water availability among habitats
Is another important factor in speciesdistribution
S li h
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Sunlight
Light intensity and quality
Can affect photosynthesis in ecosystems
Light
Is also important to the development andbehavior of organisms sensitive to the
photoperiod
Wi d
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Wind
Wind
Amplifies the effects of temperature onorganisms by increasing heat loss due to
evaporation and convection
Can change the morphology of plants
Figure 50.9
R k d S il
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Rocks and Soil
Many characteristics of soil limit the distribution
of plants and thus the animals that feed upon
them
Physical structure
pH
Mineral composition
Cli t
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Climate
Four major abiotic components make up
climate
Temperature, water, sunlight, and wind
Climate
Is the prevailing weather conditions in a
particular area
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Climate patterns can be described on two
scales
Macroclimate, patterns on the global, regional,
and local level
Microclimate, very fine patterns, such as thoseencountered by the community of organisms
underneath a fallen log
Gl b l Cli t P tt
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Global Climate Patterns
Earths global climate patterns
Are determined largely by the input of solarenergy and the planets movement in space
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Sunlight intensity
Plays a major part in determining the Earthsclimate patterns
Figure 50.10
Low angle of incoming sunlight
Sunlight directly overhead
Low angle of incoming sunlight
North Pole
60N
30N
Tropic of
Cancer
0 (equator)
30S
60S
Atmosphere
LALITUDINAL VARIATION IN SUNLIGHT INTENSITY
Tropic of
Capricorn
South pole
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Figure 50.10
June solstice: Northern
Hemisphere tilts toward
sun; summer begins in
Northern Hemisphere;
winter begins in
Southern Hemisphere.
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.
60N
30N
0 (equator)
30S
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.
December solstice: Northern
Hemisphere tilts away from sun;
winter begins in Northern
Hemisphere; summer beginsin Southern Hemisphere.
SEASONAL VARIATION IN SUNLIGHT INTENSITY
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Descending
dry air
absorbsmoisture
Ascendingmoist air
releases
moisture
Descending
dry air
absorbsmoisture
3023.5
023.5 30
Arid
zone TropicsArid
zone
60N
30N
0 (equator)
30S
60S
GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS
Air circulation and wind patterns
Play major parts in determining the Earthsclimate patterns
Figure 50.10
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GLOBAL WIND PATTERNS
Westerlies
Northeast trades
Doldrums
Southeast trades
Westerlies
Antarctic
Circle
60S
30S
0
(equator)
30N
60N
Arctic
Circle
Figure 50.10
Regional Local and Seasonal Effects on Climate
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Regional, Local, and Seasonal Effects on Climate
Various features of the landscape
Contribute to local variations in climate
Bodies of Water
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Bodies of Water
Oceans and their currents, and large lakes
Moderate the climate of nearby terrestrialenvironments
Figure 50.11
Cooler
air sinks
over water.
3
Air cools at
high elevation.
2 1 Warm air
over land rises.
4 Cool air over water
moves inland, replacing
rising warm air over land.
Mountains
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Mountains have a significant effect on
The amount of sunlight reaching an area
Local temperature
Rainfall
Mountains
Farther inland, precipitation
increases again as the air
moves up and over highermountains. Some of the worlds
deepest snow packs occur here.
Figure 50.12
3 On the eastern side of the
Sierra Nevada, there is little
precipitation. As a result of
this rain shadow, much of
central Nevada is desert.
As moist air moves in
off the Pacific Ocean and
encounters the westernmost
mountains, it flows upward,
cools at higher altitudes,
and drops a large amount
of water. The worlds tallest
trees, the coastal redwoods,
thrive here.
12
EastPacific
Ocean
Winddirection
Coast
Range
Sierra
Nevada
Seasonality
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Seasonality
The angle of the sun
Leads to many seasonal changes in localenvironments
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Lakes
Are sensitive to seasonal temperature change
Experience seasonal turnover
Figure 50.13
In spring, as the sun melts the ice, the surface water warms to 4Cand sinks below the cooler layers immediately below, eliminating the
thermal stratification. Spring winds mix the water to great depth,bringing oxygen (O2) to the bottom waters (see graphs) and
nutrients to the surface.
2
In winter, the coldest water in the lake (0C) lies just
below the surface ice; water is progressively warmer atdeeper levels of the lake, typically 45C at the bottom.
1
In autumn, as surface water cools rapidly, it sinks below theunderlying layers, remixing the water until the surface begins
to freeze and the winter temperature profile is reestablished.
4 In summer, the lake regains a distinctive thermal profile, with
warm surface water separated from cold bottom water by a narrow
vertical zone of rapid temperature change, called a thermocline.
3
Winter Spring
High
Medium
Low
O2 concentration
O2 (mg/L)
Lakedepth(m)
0 4 8 12
8
16
24
8
16
24
Lakedepth(m) O2 (mg/L)
O2 (mg/L)
Lakedepth(m)
0 4 8 12
8
16
24
O2 (mg/L)
Lakedepth(m)
0 4 8 12
8
16
24Autumn Summer
4C4
44
44
4C4
44
20
4C4
44
44
4C
6818
2022
5Thermocline
0 4 8 12
Microclimate
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Microclimate
Microclimate
Is determined by fine-scale differences inabiotic factors
Long-Term Climate Change
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Long-Term Climate Change
One way to predict future global climate
change
Is to look back at the changes that occurred
previously
Figure 50.14
Currentrange
Predicted
range
Overlap
(a) 4.5C warming over
next century(b) 6.5C warming over
next century
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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 Earths many biomes
Biomes
Are the major types of ecological associations
that occupy broad geographic regions of land
or water
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Aquatic biomes
Account for the largest part of the biosphere interms of area
Can contain fresh or salt water
Oceans
Cover about 75% of Earths surface
Have an enormous impact on the biosphere
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Many aquatic biomes
Are stratified into zones or layers defined bylight penetration, temperature, and depth
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).
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).
(a)
Littoral
zone Limneticzone
Photic
zone
Benthic
zone
Aphoticzone
Pelagic
zone
Intertidal zone
Neritic zone Oceanic zone
0
200 m
Continental
shelf
Photic zone
Pelagic
zone
Aphotic
zone
Benthic
zone
2,5006,000 m
Abyssal zone
(deepest regions of ocean floor)
(b)
Figure 50.16a, b
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Lakes
Figure 50.17An oligotrophic lake in
Grand Teton, Wyoming
A eutrophic lake in Okavango
delta, Botswana
LAKES
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Wetlands
Figure 50.17
WETLANDS
Okefenokee National Wetland Reserve in Georgia
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Estuaries
Figure 50.17 An estuary in a low coastal plain of Georgia
ESTUARIES
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Intertidal zones
Figure 50.17
INTERTIDAL ZONES
Rocky intertidal zone on the Oregon coast
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Oceanic pelagic biome
Figure 50.17 Open ocean off the island of Hawaii
OCEANIC PELAGIC BIOME
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Coral reefs
Figure 50.17 A coral reef in the Red Sea
CORAL REEFS
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Marine benthic zone
Figure 50.17 A deep-sea hydrothermal vent community
MARINE BENTHIC ZONE
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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 incertain areas
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The distribution of major terrestrial biomes
30N
Tropic of
Cancer
Equator
Tropic of
Capricorn
30S
Key
Tropical forest
Savanna
Desert
Chaparral
Temperate grassland
Temperate broadleaf forest
Coniferous forest
Tundra
High mountains
Polar ice
Figure 50.19
General Features of Terrestrial Biomes
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Terrestrial biomes
Are often named for major physical or climaticfactors and for their predominant vegetation
Stratification
Is an important feature of terrestrial biomes
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Tropical forest
TROPICAL FOREST
A tropical rain forest in BorneoFigure 50.20
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Desert
Figure 50.20
DESERT
The Sonoran Desert in southern Arizona
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Savanna
Figure 50.20
SAVANNA
A typical savanna in Kenya
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Temperate grassland
Sheyenne National Grassland in North DakotaFigure 50.20
TEMPERATE GRASSLAND
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Temperate broadleaf forest
Figure 50.20
TEMPERATE BROADLEAF FOREST
Great Smoky Mountains National Park in North Carolina
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Tundra
Figure 50.20
TUNDRA
Denali National Park, Alaska, in autumn