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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
Overview: The Scope of Ecology
• (1)Ecology is the scientific study of the interactions
between organisms and the environment
• These interactions determine distribution of
organisms and their abundance
• Ecology reveals the richness of the biosphere
• (2) Three questions
– Where they live? Why do they live where they
do? How many are there?
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 50.1: Ecology is the study of interactions
between organisms and the environment
• Ecology has a long history as a descriptive
science
• It is also a rigorous experimental science
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Ecology and Evolutionary Biology
• Events that occur in ecological time affect life on
the scale of evolutionary time
• (1) Environmental factors interacting with variation
within populations can cause evolutionary change
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Organisms and the Environment
• (2)The environment of any organism includes:
– Abiotic, or nonliving, components
– Biotic, or living, components
• All the organisms that are part of the individual’s
environment are collectively called the biota
• Environmental components affect the distribution
and abundance of organisms
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-2
Kangaroos/km2
> 20
10–20
5–10
1–5
0.1–1
< 0.1
Limits of
distribution
Tasmania
• Ecologists use observations and experiments to
test explanations for the distribution and
abundance of species
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Subfields of Ecology
• Organismal ecology studies how an organism’s
structure, physiology, and (for animals) behavior
meet environmental challenges
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LE 50-3a
Organismal ecology
• Population ecology focuses on factors affecting
how many individuals of a species live in an area
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LE 50-3b
Population ecology
• Community ecology deals with the whole array of
interacting species in a community
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LE 50-3c
Community ecology
• Ecosystem ecology emphasizes energy flow and
chemical cycling among the various biotic and
abiotic components
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LE 50-3d
Ecosystem ecology
• Landscape ecology deals with arrays of
ecosystems and how they are arranged in a
geographic region
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LE 50-3e
Landscape ecology
• The biosphere is the global ecosystem, the sum of
all the planet’s ecosystems
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Ecology and Environmental Issues
• Ecology provides the scientific understanding
underlying environmental issues
• Rachel Carson is credited with starting the modern
environmental movement
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Most ecologists follow the precautionary principle
regarding environmental issues
• It states that humans need to be concerned with
how their actions affect the environment
• (6) an ounce of prevention is worth a pound of
cure.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
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
• Many naturalists, such as Darwin and Wallace
began to identify broad patterns of distribution by
naming biogeographic realms
• Now associate these biogeographic realms with
patterns of continental drift.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-5
Palearctic
Nearctic
Tropic
of Cancer
(23.5°N)
Oriental
Ethiopian
Equator
Neotropical
(23.5°S)
Tropic of
Capricorn
Australian
• Biogeography is a good starting point for
understanding what limits geographic distribution
of species
• (1) study of the past and present distribution of
individual species.
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Dispersal and Distribution
• (2) Dispersal is movement of individuals away
from centers of high population density or from
their area of origin
• Dispersal contributes to global distribution of
organisms
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Behavior and Habitat Selection
• (3) Some organisms do not occupy all of their
potential range
• Individuals seem to avoid certain habitats even
when they are suitable.
• Species distribution may be limited by habitat
selection behavior
• ie: some insects only lay eggs on certain plants
even though larvae can feed on different kinds.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Biotic Factors
• Biotic factors that affect the distribution of
organisms may include:
– Negative interactions with other species
– Predation
– Parasitism
– disease
– Competition
– Or absence of other species (ie pollinator)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-8
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
0
August
1982
February
1983
August
1983
February
1984
Abiotic Factors
• Abiotic factors affecting distribution of organisms:
– Temperature
– Water
– Sunlight
– Wind
– Rocks and soil
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Temperature
• Environmental temperature is an important factor
in distribution of organisms because of its effects
on biological processes at the cellular level
o
– Cells freeze at temperature below 0 C
o
– Proteins denature at temperature above 45 C
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Water
• Water availability in habitats is another important
factor in species distribution
• Fresh vs salt water (osmoregulation)
• Land organisms face disiccation
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Sunlight
• Light intensity and quality affects photosynthesis
– Shading creates competition for sunlight
– Aquatic-limited by depth
• Light is also important to development and
behavior of organisms sensitive to photoperiod
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Wind
• Wind amplifies effects of temperature by
increasing heat loss from evaporation and
convection
• Wind can change morphology of plants
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Rocks and Soil
• Many characteristics of soil limit distribution of
plants and thus the animals that feed upon them:
– Physical structure
– pH
– Mineral composition
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Climate
• (6)Four major abiotic components of climate:
temperature, water, sunlight, and wind
• Climate is the prevailing weather in an area
• Macroclimate consists of patterns on the global,
regional, and local level
• Microclimate consists of very fine patterns, such
as those encountered by the community of
organisms underneath a fallen log
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Global Climate Patterns
• Global climate patterns are determined largely by
solar energy and the planet’s movement in space
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• Sunlight intensity plays a major part in determining
the Earth’s climate patterns
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-10a
North Pole
60°N
Low angle of incoming sunlight
30°N
Tropic of
Cancer
Sunlight directly overhead at equinoxes
0° (equator)
Tropic of
Capricorn
30°S
Low angle of incoming sunlight
60°S
South Pole
Atmosphere
• Seasonal variations of light and temperature
increase steadily toward the poles
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-10b
60°N
30°N
June solstice:
Northern Hemisphere
tilts toward sun;
summer begins in
Northern Hemisphere;
winter begins in
Southern
Hemisphere.
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.
December solstice:
Northern Hemisphere tilts
away from sun; winter
begins in Northern
Hemisphere; summer
begins in Southern
Hemisphere.
• Global air circulation and wind patterns play major
roles in determining climate patterns
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-10c
60°N
30°N
Descending
dry air
absorbs
moisture
0° (equator)
30°S
Ascending
moist air
releases
moisture
Descending
dry air
absorbs
moisture
0°
60°S
Arid
zone
Tropics
Arid
zone
LE 50-10d
Arctic
Circle
60°N
Westerlies
30°N
Northeast trades
Doldrums
Southeast trades
0°
(equator)
30°S
Westerlies
60°S
Antarctic
Circle
Regional, Local, and Seasonal Effects on Climate
• Various features of the landscape contribute to
local variations in climate
• Seasonal variation also influences climate
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Bodies of Water
• Oceans and their currents and large lakes
moderate the climate of nearby terrestrial
environments
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mountains
• Mountains have a significant effect on
– The amount of sunlight reaching an area
– Local temperature
– Rainfall
• South facing slopes in NA receive more
sunlight than North facing slopes and are
warmer and drier.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-12
Wind
direction
East
Pacific
Ocean
Coast
Range
Sierra
Nevada
Seasonality
• The angle of the sun leads to many seasonal
changes in local environments
• Lakes are sensitive to seasonal temperature
change and experience seasonal turnover
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Lake depth (m)
0
4
Spring
Winter
O2 (mg/L)
8
12
8
16
2°
4°
4°
4°
4°C
24
O2 concentration
0°
4°
4°
Lake depth (m)
LE 50-13
O2 (mg/L)
0
4
8
12
8
12
8
16
24
4°
4°
4°
4°C
High (>8 mg/L)
Medium (4–8 mg/L)
O2 (mg/L)
0
4
8
12
8
4°
4°
22°
20°
18°
8°
6°
5°
4°C
4°
4°
4°
4°C
16
24
Autumn
Thermocline
Summer
Lake depth (m)
Lake depth (m)
Low (<4 mg/L)
O2 (mg/L)
0
8
16
24
4
Microclimate
• Microclimate is determined by fine-scale
differences in abiotic factors
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Long-Term Climate Change
• One way to predict future global climate change is
to study previous changes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-14
Current
range
Predicted
range
Overlap
4.5°C warming over
next century
6.5°C warming over
next century
Concept 50.3: Abiotic and biotic factors influence
the structure and dynamics of aquatic biomes
• Varying combinations of biotic and abiotic factors
determine the nature of biomes
• Biomes are the major ecological associations that
occupy broad geographic regions of land or water
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Aquatic biomes account for the largest part of the
biosphere in terms of area
• They can contain fresh water or salt water
• Oceans cover about 75% of Earth’s surface and
have an enormous impact on the biosphere
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-15
30°N
Tropic of
Cancer
Equator
Tropic of
Capricorn
Continental
shelf
30°S
Key
Lakes
Rivers
Estuaries
Coral
reefs
Oceanic
pelagic zone
Intertidal
zone
Abyssal zone
(below oceanic
pelagic zone)
• Many aquatic biomes are stratified into zones or
layers defined by light penetration, temperature,
and depth
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-16a
Littoral
zone
Limnetic
zone
Photic
zone
Benthic
zone
Zonation in a lake
Pelagic
zone
Aphotic
zone
LE 50-16b
Intertidal zone
Neritic zone
0
Oceanic zone
Photic zone
200 m
Continental
shelf
Pelagic
zone
Benthic
zone
2,500–6,000 m
Abyssal zone
(deepest regions of ocean floor)
Marine zonation
Aphotic
zone
• Major aquatic biomes:
– Lakes
– Wetlands
– Streams and rivers
– Estuaries
– Intertidal zones
– Oceanic pelagic biome
– Coral reefs
– Marine benthic zone
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Concept 50.4: Climate largely determines the
distribution and structure of terrestrial biomes
• Climate is very important in determining why
terrestrial biomes are found in certain areas
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Climate and Terrestrial Biomes
• Climate has a great impact on the distribution of
organisms, as seen on a climograph
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
LE 50-18
Desert
Temperate grassland
Tropical forest
30
Temperate
broadleaf
forest
15
Coniferous
forest
0
Arctic and
alpine
tundra
–15
100
200
300
Annual mean precipitation (cm)
400
LE 50-19
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 ice
General Features of Terrestrial Biomes
• Terrestrial biomes are often named for major
physical or climatic factors and for vegetation
• Stratification is a key feature of terrestrial biomes
• Terrestrial biomes usually grade into each other,
without sharp boundaries
• The area of intergradation, called an ecotone, may
be wide or narrow
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Major terrestrial biomes:
– Tropical forest
– Desert
– Savanna
– Chaparral
– Temperate grassland
– Coniferous forest
– Temperate broadleaf forest
– Tundra
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings