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Chapter 18
An Introduction to Ecology
and the Biosphere
PowerPoint® Lectures for
Campbell Essential Biology, Fourth Edition
– Eric Simon, Jane Reece, and Jean Dickey
Campbell Essential Biology with Physiology, Third Edition
– Eric Simon, Jane Reece, and Jean Dickey
Lectures by Chris C. Romero, updated by Edward J. Zalisko
© 2010 Pearson Education, Inc.
Biology and Society:
Penguins and Polar Bears in Peril
• The great majority of scientists now agree that the global climate
is changing.
• Average global temperatures have risen 0.8°C (about 1.4°F)
over the past century, mostly over the last 30 years.
• Precipitation patterns have also changed, bringing
– Longer and more intense drought to some regions
– Flooding to other areas
• Overwhelming evidence indicates that human enterprises are
responsible for the changes that are occurring.
• Our response to this crisis will determine whether circumstances
improve or worsen.
© 2010 Pearson Education, Inc.
Figure 18.00
AN OVERVIEW OF ECOLOGY
• Ecology is the scientific study of the interactions between
organisms and their environments.
• Humans have always had an interest in other organisms and their
environments.
• Extraordinary insight can be gained from a discovery-based
approach of
– Watching nature
– Recording its structure and processes
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(a) Establishing a canopy
research station
(b) Studying the canopy
Figure 18.1
Ecology and Environmentalism
• Technological innovations have enabled humans to colonize
almost every environment on Earth.
• Earth’s resources:
– Affect our survival
– Have been greatly affected by our activities
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• Environmental problems
– Can be understood by the science of ecology
– Require decisions based on values and ethics
• On a personal level, each of us makes daily choices that affect our
ecological impact.
• Carbon footprint
– https://www3.epa.gov/carbon-footprint-calculator/
© 2010 Pearson Education, Inc.
A Hierarchy of Interactions
• Many different factors can potentially affect an organism’s
interaction with the environment.
– Biotic factors are
–
All of the organisms in the area
–
The living component of the environment
– Abiotic factors
–
Are the environment’s nonliving component
–
Include chemical and physical factors
• An organism’s habitat
– Is the specific environment it lives in
– Includes the biotic and abiotic factors of its surroundings
© 2010 Pearson Education, Inc.
• Ecology can be divided into four increasingly comprehensive
levels:
1. Organismal ecology is concerned with evolutionary adaptations
that enable individual organisms to meet the challenges posed by
their abiotic environments.
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(a) Organismal ecology
Figure 18.3a
2. Population ecology
– Addresses populations, groups of individuals of the same species living
in the same area
– Concentrates mainly on factors that affect
–
Population density
–
Growth
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(b) Population ecology
Figure 18.3b
3. Community ecology
– Is concerned with communities, all the organisms that inhabit a particular
area
– Focuses on how interactions between species affect a community’s
–
Structure
–
Organization
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(c) Community ecology
Figure 18.3c
4. Ecosystem ecology
– Is concerned with ecosystems, all the abiotic factors in addition to the
community of species in a certain area
– Focuses on energy flow and the cycling of chemicals among the various
abiotic and biotic factors
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(d) Ecosystem ecology
Figure 18.3d
LIVING IN EARTH’S DIVERSE
ENVIRONMENTS
• The biosphere is the global ecosystem, the sum of all the planet’s
ecosystems or all of life and where it lives.
• The distribution of life varies on a
– Global scale
– Regional scale
© 2010 Pearson Education, Inc.
Figure 18.4
Abiotic Factors of the Biosphere
• Patterns in the distribution of life mainly reflect differences in
abiotic factors of the environment.
• All organisms require a usable source of energy to live.
• Solar energy from sunlight
– Is captured by chlorophyll during the process of photosynthesis
– Powers most ecosystems
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Figure 18.5
• Hydrothermal vents
– Occur a mile or more below the ocean’s surface
– Are ecosystems powered by chemoautotrophic bacteria that derive energy
from the oxidation of inorganic chemicals such as hydrogen sulfide
© 2010 Pearson Education, Inc.
Figure 18.6
Temperature
• Temperature affects metabolism.
– Few organisms can maintain a sufficiently active metabolism at
temperatures close to 0ºC.
– Temperatures above 45ºC destroy the enzymes of most organisms.
• Extraordinary adaptations enable some species to live outside this
temperature range.
– Communities consisting of bacteria, algae, and small invertebrates inhabit
sea ice at both poles.
– Bacteria and archaea
–
Can live in hot springs
–
Have enzymes that function optimally at extremely high
temperatures
© 2010 Pearson Education, Inc.
Figure 18.7
Water
• Water is essential to all life.
• For terrestrial organisms, the main water problem is drying out.
• Aquatic organisms
– Are surrounded by water
– Face problems of water balance if their own solute concentration does not
match that of their surroundings
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Animal cell
H2O
H2O
H 2O
Normal
Lysing
H 2O
Flaccid (wilts)
(a) Isotonic
solution
Shriveled
Plasma
membrane
Plant cell
H 2O
H2O
H 2O
Turgid
(b) Hypotonic
solution
H 2O
Shriveled
(c) Hypertonic
solution
Figure 5.14
Figure 5.15
Nutrients
• The distribution and abundance of plants is often determined by
the
– Availability of nitrogen and phosphorus
– The structure, pH, and nutrient content of the soil
• In many aquatic ecosystems the growth of algae and
photosynthetic bacteria is often limited by levels of
– Nitrogen & Phosphorus
– The levels of dissolved oxygen and salinity
– Currents & Tides
© 2010 Pearson Education, Inc.
Figure 18.8
Other Terrestrial Factors
• Terrestrial but not aquatic ecosystems are more limited by
– Wind
– Storms
– Fire
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The Evolutionary Adaptations of Organisms
• The ability of organisms to live in Earth’s diverse environments
demonstrates the close relationship between the fields of
– Ecology
– Evolutionary biology
• Evolutionary adaptation via natural selection results from the
interactions of
– Organisms
– Their environments
• The abiotic factors in a habitat may vary from year to year,
seasonally, or over the course of a day.
© 2010 Pearson Education, Inc.
• Birds may adjust to cold by
– Migrating to warmer regions
– Growing heavier feathers
– Fluffing up their feathers to trap more heat
• These responses, that occur during the lifetime of an individual,
do not qualify as evolution, which is change in a population over
time.
© 2010 Pearson Education, Inc.
Figure 18.9
Physiological Responses
• Acclimation is a
– Gradual, reversible, physiological adjustment to an environmental change
• The ability to acclimate is generally related to the range of
environmental conditions a species naturally experiences.
• Among vertebrates
– Birds and mammals can tolerate the greatest temperature extremes
because they are endotherms
– Ectothermic reptiles can only tolerate more limited climates
© 2010 Pearson Education, Inc.
Key
Number of lizard species
=0
= 1–5
= 6–10
= 11–15
= 16–20
= 20+
Figure 18.10
Anatomical Responses
• Many organisms respond to environmental challenges with some
type of change in
– Body shape
– Structure
• Reversible change, such as a heavier fur coat in response to cold,
is an example of acclimation.
• Environmental variation can irreversibly affect
– Growth
– Development
© 2010 Pearson Education, Inc.
Figure 18.11
Figure 18.12
Behavioral Responses
• In contrast to plants, most animals can respond to an unfavorable
change in the environment by moving to a new location.
– Ectotherms may shuttle between sun and shade.
– Migratory birds travel great distances in response to changing seasons.
– Humans have an especially rich range of behavioral responses.
© 2010 Pearson Education, Inc.
Figure 18.13
BIOMES
• A biome is
– A major terrestrial or aquatic life zone characterized by
–
Vegetation type in terrestrial biomes
–
The physical environment in aquatic biomes
• Aquatic biomes
– Occupy roughly 75% of Earth’s surface
– Are determined by their
–
Salinity
–
Other physical factors
© 2010 Pearson Education, Inc.
• Freshwater biomes
– Typically have a salt concentration of less than 1%
– Include lakes, streams, rivers, and wetlands
• Marine biomes
– Typically have a salt concentration around 3%
– Include oceans, intertidal zones, coral reefs, and estuaries
© 2010 Pearson Education, Inc.
Freshwater Biomes
• Freshwater biomes
– Cover less than 1% of Earth
– Contain a mere 0.01% of its water
– Harbor about 6% of all described species
– Are used for drinking water, crop irrigation, sanitation, and industry
• Freshwater biomes fall into two broad groups:
– Standing water, which includes lakes and ponds
– Flowing water, such as rivers and streams
© 2010 Pearson Education, Inc.
Figure 18.14
• In lakes and large ponds, the communities of plants, algae, and
animals are distributed according to the
– Depth of water
– Distance from shore
• The photic zone, named because light is available for
photosynthesis, includes
– The shallow water near shore
– The upper layer of water away from shore
• The aphotic zone
– Is deeper
– Has light levels too low to support photosynthesis
© 2010 Pearson Education, Inc.
Photic
zone
Benthic
realm
Aphotic
zone
Figure 18.15
• The benthic realm is
– At the bottom of all aquatic biomes
– Made up of sand and organic and inorganic sediments
– Occupied by communities of organisms that are collectively called
benthos
© 2010 Pearson Education, Inc.
Rivers and Streams
• Rivers and streams
– Are bodies of water flowing in one direction
– Generally support quite different communities of organisms than lakes
and ponds
• Near the source of a stream, the water is usually
– Clear, Cold , Swift, and Low in nutrients
• Downstream, the water is usually
– Murkier, Warmer, Slower, and Higher in nutrients
• Many streams and rivers have been affected by pollution from
human activities and dams to control floods, to provide reservoirs
for drinking water, or to generate hydroelectric power.
© 2010 Pearson Education, Inc.
Figure 18.16
Dam
Canada
U.S.
Flathead
Lake
N
MT
Seattle
WA
Portland
ID
OR
CA
NV
Figure 18.17
Wetlands
• A wetland is a transitional biome between an aquatic ecosystem
and a terrestrial one.
• Wetlands
– Support the growth of aquatic plants
– Are among the richest of biomes in terms of species diversity
© 2010 Pearson Education, Inc.
Figure 18.18
Marine Biomes
• Marine biomes are diverse, ranging from vivid coral reefs to
perpetually dark realms in the deepest regions.
• As in freshwater biomes, the seafloor is known as the benthic
realm.
• In shallow areas such as the submerged parts of continents, called
continental shelves, the photic zone includes pelagic and benthic
regions.
• In these sunlit areas photosynthesis by phytoplankton
(photosynthetic algae and bacteria) and multicellular algae
provides energy for a diverse community of animals.
© 2010 Pearson Education, Inc.
High tide
Low tide
Pelagic realm (open water)
Sea star
(to 33 cm)
Oarweed (to 2 m)
Brain coral
(to 1.8 m) PhytoZooplankton plankton
Intertidal Continental
zone
shelf
Sponges
(1 cm–1 m)
Turtle
(60–180 cm)
Blue shark (to 2 m)
Photic
zone
200 m
Sperm whale
(10–20 cm)
Sea pen
(to 45 cm)
Benthic realm
(seafloor from continental
shelf to deep-sea bottom)
Man-of-war
(to 50 m long)
Octopus
(to 10 m)
Sea spider
(1–90 cm)
Brittle
star
(to 60 cm) Glass
Rat-tail fish
(to 80 cm)
Hatchet fish
(2–60 cm)
Gulper eel
(to 180 cm)
Anglerfish
(45 cm–2 m)
sponge Sea cucumber Tripod fish
(to 30 cm)
(to 1.8 m)
(to 40 cm)
“Twilight”
Aphotic
zone
1,000–
4,000 m
No light
6,000–
10,000 m
Figure 18.19
• The pelagic zone includes
– Zooplankton (free-floating animals, including many microscopic ones)
– Fish
– Marine mammals
• The coral reef biome occurs in the photic zone of warm tropical
waters, in scattered locations around the globe.
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Figure 18.20
• The photic zone extends down a maximum of 200m in the ocean.
• The region between 200 and 1000 meters is
– Dimly lit, sometimes called the twilight zone
– Dominated by a fascinating variety of small fish and crustaceans
• The intertidal zone is where
– The ocean meets land
– The shore is pounded by waves during high tide
– The bottom is exposed to the sun and drying winds during low tide
© 2010 Pearson Education, Inc.
Figure 18.21
• Estuaries
– Are a transition area between a river and the ocean
– Have a saltiness ranging from nearly that of fresh water to that of the
ocean
– Are among the most productive areas on Earth
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Figure 18.22
• Estuaries are threatened by
– Landfills
– Nutrient pollution
– Contamination by pathogens or toxic chemicals
– Alteration of freshwater inflow
– The introduction of non-native species
© 2010 Pearson Education, Inc.
How Climate Affects Terrestrial Biome
Distribution
• Terrestrial biomes are primarily determined by
– Temperature
– Rainfall
– Vegetation type
• Earth’s global climate patterns are largely the result of
– The input of radiant energy from the sun
– The planet’s movement in space
© 2010 Pearson Education, Inc.
North Pole
60º N
Low angle of
incoming sunlight
30º N
Tropic of
Cancer
Sunlight strikes
most directly
0º (equator)
Tropic of
Capricorn
30º S
Low angle of
incoming sunlight
Atmosphere
60º S
South Pole
Figure 18.23
• Heated by the direct rays of the sun, air at the equator rises, then
cools forming clouds, and drops rain.
• This largely explains why rain forests are concentrated in the
tropics, the region from the Tropic of Cancer to the Tropic of
Capricorn.
© 2010 Pearson Education, Inc.
Descending
dry air
absorbs
moisture
Ascending
moist air
Trade winds releases Trade winds
moisture
Descending
dry air
absorbs
moisture
Doldrums
0º
Temperate
zone
Tropics
Temperate
zone
Figure 18.24
• Temperate zones
– Occur in latitudes between the tropics and the Arctic Circle in the north
and the Antarctic Circle
– Generally have milder climates than the tropics or the polar regions
• Climate is also affected by
– Proximity to large bodies of water
– The presence of landforms such as mountain ranges
• Mountains affect climate in two major ways.
– First, air temperature drops as elevation increases.
– Second, mountains can block the flow of cool, moist air from a coast and
cause radically different climates on opposite sides of a mountain range
© 2010 Pearson Education, Inc.
Spruce-fir forest
10,000
9,000
8,000
Oak woodland
7,000
6,000
Desert grassland
5,000
Elevation (feet)
Pine woodland
4,000
Desert
3,000
Figure 18.25
Wind
direction
East
Pacific
Ocean
Coast
Range
Cascade
Range
Rain
shadow
Figure 18.26
30º N
Tropic of
Cancer
Equator
Tropic of
Capricorn
30º S
Key
Tropical forest
Savanna
Desert
Chaparral
Temperate grassland
Temperate broadleaf forest
Coniferous forest
Arctic tundra
High mountains (coniferous forest and
alpine tundra)
Polar ice
Figure 18.27
• A climograph is a visual representation of the differences in
– Precipitation
– Temperature ranges that characterize terrestrial biomes
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Annual mean temperature (ºC)
Key
30
Tropical
forest
Desert
15
Temperate
grassland
Temperate
broadleaf
forest
0
15
0
400
100
200
300
Annual mean precipitation (cm)
Coniferous
forest
Tundra
Figure 18.28
Tropical Forest
• Tropical forests occur in equatorial areas, where the temperature
is warm, and where days are 11–12 hours long year-round.
© 2010 Pearson Education, Inc.
Figure 18.29
Precipitation
Temperature
Savanna
• Savannas
– Are dominated by grasses and scattered trees
– Are warm year-round
– Experience rainfall (roughly 12–20 inches per year) with dramatic
seasonal variation
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Figure 18.30
Fire
Precipitation
Temperature
Desert
• Deserts
– Are the driest of all biomes
– May be very hot or very cold
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Figure 18.31
Precipitation
Temperature
Chaparral
• Chaparral has a climate that results from cool ocean currents
circulating offshore and producing mild, rainy winters and hot,
dry summers.
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Figure 18.32
Fire
Precipitation
Temperature
Temperate Grassland
• Temperate grasslands
– Are mostly treeless
– Have 10–30 inches of rain per year
– Experience frequent droughts and fires
– Are characterized by grazers including bison and pronghorn in North
America
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Figure 18.33
Fire
Precipitation
Temperature
Temperate Broadleaf Forest
• Temperate broadleaf forest
– Occurs throughout midlatitudes where there is sufficient moisture to
support the growth of large trees
– Includes dense stands of deciduous trees in the Northern Hemisphere
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Figure 18.34
Precipitation
Temperature
Coniferous Forest
• Coniferous forests
– Are dominated by cone-bearing evergreen trees
– Include the northern coniferous forest, or taiga, the largest terrestrial
biome on Earth
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Figure 18.35
Precipitation
Temperature
• Temperate rain forests
– Are found along coastal North America from Alaska to Oregon
– Are also coniferous forest
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Tundra
• Tundra
– Covers expansive areas of the Arctic between the taiga and polar ice
– Is characterized by
–
Permafrost (permanently frozen subsoil)
–
Bitterly cold temperatures
–
High winds
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Figure 18.36
Precipitation
Temperature
Polar Ice
• Polar ice covers the land at high latitudes north of the arctic
tundra in the northern hemisphere and Antarctica in the southern
hemisphere.
• Only a small portion of these land masses is free of ice or snow,
even during the summer.
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Figure 18.37
Precipitation
Temperature
The Water Cycle
• All parts of the biosphere are linked by the global water cycle.
• Human activities that affect the global water cycle include
– Destruction of forests
– Pumping large amounts of groundwater to the surface for irrigation
© 2010 Pearson Education, Inc.
Solar
heat
Water vapor
over the sea
Precipitation
over the sea
Net movement
of water vapor
by wind
Evaporation
from the sea
Water vapor
over the land
Precipitation
over the land
Evaporation
and
transpiration
Oceans
Flow of water
from land to sea
Surface water
and groundwater
Figure 18.38
Human Impact on Biomes
• Sustainability is the goal of developing, managing, and
conserving Earth’s resources in ways that meet the needs of
people today without compromising the ability of future
generations to meet their needs.
• Every year, more and more forested land is cleared for
agriculture.
© 2010 Pearson Education, Inc.
• Satellite photos of a small area in Brazil show how thoroughly a
landscape can be altered in a short amount of time.
1975
2001
Figure 18.39
Figure 18.40
Fresh Water
• The impact of human activities on freshwater ecosystems may
pose an even greater threat to life on Earth—including
ourselves—than the damage to terrestrial ecosystems.
• Las Vegas, the population center of Clark County, Nevada, is one
example of a city whose water resources are increasingly stressed
by drought and overuse.
• The water level in Lake Mead has
– Dropped drastically
– Parched cities and farms farther downstream, which are pleading for more
water
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(a) May 1973
(b) May 2000
Figure 18.41
Figure 18.42
GLOBAL CLIMATE CHANGE
• Global climate patterns are changing because of rising
concentration in the atmosphere of
– Carbon dioxide (CO2)
– Some other gases
• Greenhouse gases
– Include CO2, water vapor, and methane
– Are transparent to solar radiation
– Absorb or reflect heat
– Contribute to increases in global temperatures
© 2010 Pearson Education, Inc.
Some heat
energy escapes
into space
Sunlight
Atmosphere
Radiant heat
trapped by
greenhouse gases
Figure 18.43
• Warming is:
– Greater over land than sea
– Greatest in the northernmost regions of the Northern Hemisphere and the
Antarctic Peninsula
• The vast majority of scientists are confident that human activities
have caused the rising concentrations of greenhouse gases.
• Overall, the uptake of CO2 by photosynthesis roughly equals the
release of CO2 by cellular respiration.
© 2010 Pearson Education, Inc.
Antarctic
Peninsula
2
1.6
1.2
0.8
0.4
0.2
0.2
0.4
0.8
1.2
1.6
2.1
Figure 18.44
Carbon dioxide (CO2) (ppm)
400
350
300
250
0
500
1000
1500
2000
Year
Figure 18.45
Atmosphere
Photosynthesis
Respiration
Combustion
of fossil fuel
Ocean
Figure 18.46
The Process of Science: How Does
Climate Change Affect Species Distribution?
• Observations:
– Average temperatures in Europe have risen 0.8ºC.
– Butterflies are sensitive to temperature change.
• Question: Have the ranges of butterflies changed in response to
the temperature changes?
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• Hypothesis: Butterfly range boundaries are shifting in line with
the warming trend.
• Prediction: Butterfly
– Species will establish new populations to the north of their former ranges
– Populations at the southern edges of their ranges will become extinct
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• Experiment: Historical data on the ranges of 35 species of
butterflies in Europe were analyzed.
• Results:
– More than 60% of the species have pushed their northern range
boundaries poleward over the last century.
– The southern boundaries have simultaneously contracted for some
species, but not for others.
© 2010 Pearson Education, Inc.
Finland
Sweden
Norway
Estonia
Russia
Lativia
Denmark
Lithuania
Europe
Africa
Argynnis paphia (silver-washed fritillary butterfly)
Figure 18.47
Effects of Climate Change on Ecosystems
• In many plants and animals, life cycle events are triggered by
– Warming temperatures
– Day length
• As global temperatures warm, and day length remains steady,
natural interactions may become out of sync.
– Plants may bloom before pollinators have emerged.
– Eggs may hatch before dependable food sources are available.
• The combined effects of climate change on forest ecosystems in
western North America have spawned catastrophic wildfire
seasons.
© 2010 Pearson Education, Inc.
Figure 18.48
• Warmer weather helps bark beetles
– Bore into drought-stressed conifers
– Reproduce twice a year instead of just once
• Emissions of greenhouse gases are accelerating.
• From 2000–2005 global CO2 emissions increased four times
faster than in the preceding 10-year span.
© 2010 Pearson Education, Inc.
Figure 18.49
• The amount of greenhouse gas emitted as the result of the actions
of a single individual is that person’s carbon footprint.
• We can reduce our carbon footprints by
– Reducing our use of energy
– Driving less
– Recycling
• In addition, eating locally grown fresh foods may lower the
greenhouse gas emissions that result from food processing and
transportation.
© 2010 Pearson Education, Inc.
Figure 18.50
Figure 18.51
Evolution Connection:
Climate Change as an Agent of Natural Selection
• Can evolutionary adaptations counteract the negative effects of
climate change on organisms?
• The species most likely to adapt have
– High genetic variability
– Short life spans
© 2010 Pearson Education, Inc.
(a) Pitcher plant mosquito
(b) Adélie penguin
Figure 18.52