Download - Chapter 34 and 36
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Chapter 34Chapter 34
The Biosphere: An Introduction to Earth’s Diverse Environments
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A Mysterious Giant of the Deep
• There are about 1,000 known species of squid
– But until recently, no one had reported on this “mystery squid”
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• Deep-sea submersibles
– Are allowing scientists to study uncharted depths of the ocean
Figure A
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• At depths of up to 2,500 meters
– Scientists are observing new environments and a great variety of organisms
Figure B Figure C
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• Ecology
– Is the scientific study of the interactions of organisms with their environments
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34.1 Ecologists study how organisms interact with their environment at several levels
• At the organismal level
– Ecologists may examine how one kind of organism meets the challenges of its environment
Figure 34.1
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• At the population level
– Ecologists might study factors that limit population size
• At the community level
– An ecologist might focus on interspecies interactions
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• Ecosystem interactions involve
– Living (biotic) communities and nonliving (abiotic) physical and chemical factors
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THE BIOSPHERE
34.2 The biosphere is the total of all of Earth’s ecosystems
• The biosphere
– Is the global ecosystem
Figure 34.2A
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• Patchiness of the environment
– Characterizes the biosphere
Figure 34.2B
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CONNECTION
34.3 Environmental problems reveal the limits of the biosphere
• Human activities, including the widespread use of chemicals
– Affect all parts of the biosphere
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• Rachel Carson, a famous ecologist
– Was one of the first people to perceive the global dangers of pesticide use
Figure 34.3
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34.4 Physical and chemical factors influence life in the biosphere
• Abiotic factors determining the biosphere’s structure and dynamics include
– Solar energy, water, temperature, wind, and disturbances
Figure 34.4
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34.5 Organisms are adapted to abiotic and biotic factors by natural selection
• Unique adaptations
– Allow the survival of organisms in particular habitats
Figure 34.5
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• Biotic factors, such as predation and competition
– Can lead to the evolution of adaptations by natural selection
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34.6 Regional climate influences the distribution of biological communities
• Most climatic variations
– Are due to the uneven heating of Earth’s surface as it orbits the sun
Low angle ofincoming sunlight
Sunlight strikesmost directly
Low angle of incoming sunlight
Atmosphere
60ºSSouth Pole
Tropic ofCapricorn30ºS
0º (equator)
30ºNTropic ofCancer
North Pole60ºN
Figure 34.6A
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• The tilt of the Earth’s axis
– Causes the changes of the seasons in the northern and southern hemispheres
June solstice(Northern
Hemisphere tiltstoward sun)
March equinox(equator facessun directly)
Constant tiltof 23.5º
Septemberequinox
Decembersolstice(Northern
Hemisphere tiltsaway from sun)
Figure 34.6B
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• The uneven heating of the Earth
– Also sets up patterns of precipitation and prevailing winds
Descendingdry airabsorbsmoisture Trade winds
Ascendingmoist airreleasesmoisture
Trade winds
Descendingdry airabsorbsmoisture
Doldrums
Temperatezone
TropicsTemperate
zone
30º23.5º 0º 23.5º
30º
60ºN
30ºN
30ºS
Figure 34.6C, D
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• Ocean currents
– Influence coastal climateFresno104º
Paso Robles93º Bakersfield
106º
DeathValley119º
Pacific Ocean
Santa Barbara 75º
Los Angeles(Airport) 74º
San Diego 75º
40 miles
San Bernardino 101º
Riverside 91º
Palm Springs 104º
Burbank86º
Santa Ana84º
Key70s (ºF)
80s
90s
100s
110s
Figure 34.6E
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PacificOcean
CoastRange
Winddirection
SierraNevada
East
Figure 34.6F
• Landforms such as mountains
– Affect rainfall
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AQUATIC BIOMES
34.7 Oceans occupy most of Earth’s surface
• Several characteristics shape ocean communities
– Light, distance from shore, and the availability of nutrients
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• The intertidal zone, an oceanic zone
– Is the area of shore where the ocean meets the land
Figure 34.7A
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• Oceanic zones also include
– The pelagic and benthic zonesIntertidal zone
Photic zone0
200 mContinentalshelf
2,500–6,000 m
Benthic zone(seafloor)
Pelagiczone
Aphoticzone
Figure 34.7B
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• Coral reefs
– Are found in warm waters above continental shelves
Figure 34.7C
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• Estuaries
– Are productive areas where rivers flow into the ocean
Figure 34.7D
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34.8 Freshwater biomes include lakes, ponds, rivers, streams, and wetlands
• Factors that shape lake and pond communities include
– Light, temperature, and the availability of nutrients and dissolved oxygen
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• Abiotic factors change from the source of a river to its mouth
– And communities vary accordingly
Figure 34.8A
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• Wetlands include
– Marshes and swamps
Figure 34.8B
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TERRESTRIAL BIOMES
34.9 Terrestrial biomes reflect regional variations in climate
• Temperature and rainfall
– Mainly determine the terrestrial biomes
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• Major terrestrial biomes
30ºN
Tropic ofCancer
Equator
Tropic ofCapricorn
30ºS
Tropical forest
SavannaDesertChaparral
Temperate grassland
Temperate broadleaf forestConiferous forest
Tundra
High mountains
Polar ice
Figure 34.9
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34.10 Tropical forests cluster near the equator
• Tropical rain forests
– Are the most diverse ecosystem
Figure 34.10
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34.11 Savannas are grasslands with scattered trees
• Savannas
– Are dry and warm
Figure 34.11
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34.12 Deserts are defined by their dryness
• Deserts
– Are the driest biomes
Figure 34.12
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34.13 Spiny shrubs dominate the chaparral
• The chaparral
– Is a shrubland with cool, rainy winters and dry, hot summers
Figure 34.13
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34.14 Temperate grasslands include the North American prairie
• Temperate grasslands
– Are found where winters are cold
Figure 34.14
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34.15 Broadleaf trees dominate temperate forests
• Temperate broadleaf forests grow throughout midlatitude regions
– Where there is sufficient moisture to support the growth of large trees
Figure 34.15
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34.16 Coniferous forests are often dominated by a few species of trees
• The northern coniferous forest, or taiga
– Is found where there are short summers, and long, snowy winters
Figure 34.16
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34.17 Long, bitter-cold winters characterize the tundra
• Arctic tundra
– Is a treeless biome characterized by extreme cold, wind, and permafrost
Figure 34.17
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• Alpine tundra
– Occurs above the treeline on high mountains
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TALKING ABOUT SCIENCE
34.18 Ecologist Ariel Lugo studies tropical forests in Puerto Rico
• The Luquillo Experimental Forest
– Allows ecologists to study the effects of disruption on tropical forests
Figure 34.18A, B
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PowerPoint Lectures forBiology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon
Lectures by Chris Romero
Chapter 36Chapter 36
Population Dynamics
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The Spread of Shakespeare’s Starlings
• The European Starling
– Has become an abundant and destructive pest in North America
Europeanstarling
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• Starling populations have become very successful
– And spread throughout North America since their introduction in 1890
Current
1955
1945
1935 1925
19151905
19251935
1945
1955Current
The spread of starlings across North America
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• Population ecology
– Is concerned with changes in population size and the factors that regulate populations over time
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36.1 Population ecology is the study of how and why populations change
• A population
– Is a group of individuals of a single species that occupy the same general area
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POPULATION STRUCTURE AND DYNAMICS
36. 2 Density and dispersion patterns are important population variables
• Population density
– Is the number of individuals of a species per unit of area or volume
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• Environmental and social factors
– Influence the spacing of individuals in various dispersion patterns: clumped, uniform, or random
Figure 36.2A Figure 36.2B
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36.3 Life tables track mortality and survivorship in populations
• Life tables and survivorship curves
– Predict an individual’s statistical chance of dying or surviving during each interval of the individual’s lifetime
Table 36.3
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• The three types of survivorship curves
– Reflect species’ differences in reproduction and mortality
Pe
rce
nta
ge
of
surv
ivo
rs (
log
sca
le) 100
10
1
0.10 50 100
III
II
I
Percentage of maximum life spanFigure 36.3
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36.4 Idealized models help us understand population growth
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The Exponential Growth Model
• Exponential growth
– Is the accelerating increase that occurs when growth is unlimited
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• The equation G rN describes this J-shaped curve
– G the population growth rate
– r an organism’s inherent capacity to reproduce
– N the population size
Figure 36.4A
Time Number of Cells
0 minutes
20
40
60
80
100
120 (= 2 hours)
3 hours
4 hours
8 hours
12 hours
1
2
4
8
16
32
64
512
4,096
16,777,216
68,719,476,736
= 20
= 21
= 22
= 23
= 24
= 25
= 26
= 29
= 212
= 224
= 236
Num
ber
of b
acte
rial c
ells
(N
)
70
60
50
30
40
20
10
00 20 40 60 80 100 120 140
G = r N
Time (min)
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Limiting Factors and the Logistic Growth Model
• Limiting factors
– Are environmental factors that restrict population growth
Bre
edin
g m
ale
fur
seal
s(t
hous
ands
)10
8
6
4
2
01915 1925 1935 1945
YearFigure 36.4B
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• Logistic growth
– Is the model that represents the slowing of population growth as a result of limiting factors
– Levels off at the carrying capacity, which is the number of individuals the environment can support
Nu
mb
er
of
ind
ivid
ua
ls (
N)
K
0Time
G = r N
G = r N(K – N)
K
Figure 36.4C
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• The equation G rN(K – N)/K describes a logistic growth curve
– Where K carrying capacity and (K – N)/K accounts for the leveling off of the curve
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36.5 Multiple factors may limit population growth
• As a population’s density increases
– Factors such as limited food supply and increased disease or predation may increase the death rate, decrease the birth rate, or both
4.0
3.6
3.8
3.4
3.2
3.0
2.80 10 20 30 40 50 60 70 80
Density of females
Clu
tch
size
Figure 36.5A
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• Abiotic factors such as weather
– May limit many natural populations
Exponentialgrowth
Suddendecline
Num
ber
of
aph
ids
Apr May Jun Jul Aug Sep Oct Nov DecFigure 36.5B
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• Most populations
– Are probably regulated by a mixture of factors, and fluctuations in numbers are common
Time (years)
1975 1980 1985 1990 1995 20000
20
40
80
60
Num
ber
of f
emal
es
Figure 36.5C
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36.6 Some populations have “boom-and-bust” cycles
• Some populations
– Undergo regular boom-and-bust cycles of growth and decline
160
120
80
40
01850 1875 1900 1925
9
6
3
0
Snowshoe hare
Lynx
Har
e po
pula
tion
size
(tho
usan
ds)
Lynx
pop
ulat
ion
size
(tho
usan
ds)
Year Figure 36.6
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36.7 Evolution shapes life histories
• An organism’s life history
– Is the series of events from birth through reproduction to death
LIFE HISTORIES AND THEIR EVOLUTION
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• Populations with so-called r-selection life history traits
– Produce many offspring and grow rapidly in unpredictable environments
Figure 36.7A
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• Populations with K-selected traits
– Raise few offspring and maintain relatively stable populations
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• Life history traits
– Are shaped by natural selection
Experimentaltransplant ofguppies
Predator: Killifish;preys mainly on small,immature guppies
Guppies: Larger atsexual maturity thanthose in pike-cichlidpools
Predator: Pike-cichlid;preys mainly on large,mature guppies
Guppies: Smaller atsexual maturity thanthose in killifish poolsFigure 36.7B
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36.8 Principles of population ecology have practical applications
• Principles of population ecology
– Are useful in managing natural resources
CONNECTION
900
800
700
600
500
400
300
200
100
01960 1970 1980 1990 2000
Yie
ld (
thou
sand
s of
met
ric t
ons)
Figure 36.8
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THE HUMAN POPULATION CONNECTION
The Plague
6
5
4
3
2
1
08000B.C.
4000B.C.
3000B.C.
2000B.C.
1000B.C.
0 1000A.D.
2000A.D.
Hum
an p
opul
atio
n si
ze (
billi
ons)
Figure 36.9A
36.9 Human population growth has started to slow after centuries of exponential increase
•The human population
– Has been growing almost exponentially for centuries, standing now at about 6.4 billion
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• The ecological footprint
– Represents the amount of land per person needed to support a nation’s resource needs
16
14
12
10
8
6
4
2
00 2 4 6 8 10 12 14 16
Available ecological capacity (ha per person)
Eco
log
ica
l fo
otp
rint
(ha
pe
r p
ers
on
)
Japan
UK
Spain
Germany
NetherlandsNorway
USA
World
ChinaIndia
Sweden
Canada
Australia
New Zealand
Figure 36.9B
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• The ecological capacity of the world
– May already be smaller than the population’s ecological footprint
Traffic in downtown Cairo, Egypt
Manhattan,New York City
Refugee camp in ZaireFigure 36.9C
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36.10 Birth and death rates and age structure affect population growth
• The demographic transition
– Is the shift from high birth rates and death rates to low birth rates and death rates
50
40
30
20
10
01900 1925 1950 1975 2000 2025 2050
Year
Birth rate
Death rate
Birt
h or
dea
th r
ate
per
1,00
0 po
pula
tion
Figure 36.10A
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• The age structure of a population
– Is the proportion of individuals in different age-groups
– Affects its future growth
Age85+
80–8475–7970–7465–6960–6455–5950–5445–4940–4435–3930–3425–2920–2415–1910–145–90–4
8 46 2 0 2 4 6 8 6 4 2 0 2 4 6 6 4 2 0 2 4 6
Percent of population Percent of population Percent of population
Primaryreproductive
ages
Rapid growth Slow growth Decrease
Afghanistan United States Italy
Male Female Male Female Male Female
Figure 36.10B
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• Increasing the status of women
– May help to reduce family size