Ecology Biology Lecture

1. An Introduction to Ecology, the Biosphere and Ecosystems
By Konstantinos Kosmidis

2. • 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

3. • Ecology
– Is an enormously complex and exciting area of
biology
– Reveals the richness of the biosphere

4. • Ecology is the study of interactions between
organisms and the environment
• Ecology
– Has a long history as a descriptive science
– Is also a rigorous experimental science

5. Ecology and Evolutionary Biology
• Events that occur in ecological time
– Affect life on the scale of evolutionary time

6. 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, the
biota

7. • 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
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

8. • Ecologists
– Use observations and experiments to test
explanations for the distribution and abundance of
species

9. Subfields of Ecology
• Organismal ecology
– Studies how an organism’s structure, physiology, and
(for animals) behavior meet the challenges posed by
the environment
(a) Organismal ecology. How do humpback whales
select their calving areas?

10. • Population ecology
– Concentrates mainly on factors that affect how
many individuals of a particular species live in an
area
Population ecology.
What environmental
factors affect the
reproductive rate of
deer mice?
(b)

11. • 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?

12. • 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?

13. • Landscape ecology
– Deals with arrays of ecosystems and how they are
arranged in a geographic region
(e) Landscape ecology. To what extent do the trees lining the
drainage channels in this landscape serve as corridors of
dispersal for forest animals?

14. • The biosphere
– Is the global ecosystem, the sum of all the planet’s
ecosystems

15. Ecology and Environmental Issues
• Ecology
– Provides the scientific understanding underlying
environmental issues
• Rachel Carson
– Is credited
with starting
the modern
environmental
movement

16. • 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 the environment

17. • 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

18. • Many naturalists
– Began to identify broad patterns of distribution by
naming biogeographic realms
Tropic
of Cancer
(23.5N)
Equator
Nearctic
Neotropical
Ethiopian
Oriental
Australian
Palearctic
(23.5S)
Tropic of
Capricorn

19. • Biogeography
– Provides a good starting point for understanding
what limits the geographic distribution of species
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 selection
Predation, parasitism,
competition, disease
Water
Oxygen
Salinity
pH
Soil nutrients, etc.
Temperature
Light
Soil structure
Fire
Moisture, etc.
Chemical
factors
Physical
factors

20. 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

21. New areas
occupied Year
1996
1989
1974
Natural Range Expansions
• Natural range expansions
– Show the influence of dispersal on distribution

22. Species Transplants
• Species transplants
– Include organisms that are intentionally or
accidentally relocated from their original
distribution
– Can often disrupt the communities or ecosystems to
which they have been introduced

23. Behavior and Habitat Selection
• Some organisms
– Do not occupy all of their potential range
• Species distribution
– May be limited by habitat selection behavior

24. Biotic Factors
• Biotic factors that affect the distribution of
organisms may include
– Interactions with other species
– Predation
– Competition

25. Abiotic Factors
• Abiotic factors that affect the distribution of
organisms may include
– Temperature
– Water
– Sunlight
– Wind
– Rocks and soil

26. Temperature
• Environmental temperature
– Is an important factor in the distribution of
organisms because of its effects on biological
processes

27. Water
• Water availability among habitats
– Is another important factor in species distribution

28. Sunlight
• Light intensity and quality
– Can affect photosynthesis in ecosystems
• Light
– Is also important to the development and behavior
of organisms sensitive to the photoperiod

29. Wind
• Wind
– Amplifies the effects of temperature on organisms
by increasing heat loss due to evaporation and
convection
– Can change the morphology of plants

30. 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

31. Climate
• Four major abiotic components make up climate
– Temperature, water, sunlight, and wind
• Climate
– Is the prevailing weather conditions in a particular
area

32. • 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

33. Global Climate Patterns
• Earth’s global climate patterns
– Are determined largely by the input of solar energy
and the planet’s movement in space

34. • Sunlight intensity
– Plays a major part in determining the Earth’s climate
patterns
Low angle of incoming sunlight
Sunlight directly overhead
Low angle of incoming sunlight
North Pole
60N
30N
Tropic of
Cancer
0 (equator)
30S
60S
Atmosphere
LALITUDINAL VARIATION IN SUNLIGHT INTENSITY
Tropic of
Capricorn
South pole

35. 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.
60N
30N
0 (equator)
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.
SEASONAL VARIATION IN SUNLIGHT INTENSITY

36. Descending
dry air
absorbs
moisture
Ascending
moist air
releases
moisture
Descending
dry air
absorbs
moisture
0
Arid
zone Tropics
Arid
zone
60N
30N
0 (equator)
30S
60S
GLOBAL AIR CIRCULATION AND PRECIPITATION PATTERNS
• Air circulation and wind patterns
– Play major parts in determining the Earth’s climate
patterns

37. GLOBAL WIND PATTERNS
Westerlies
Northeast trades
Doldrums
Southeast trades
Westerlies
Antarctic
Circle
60S
30S
0
(equator)
30N
60N
Arctic
Circle

38. Regional, Local, and Seasonal Effects on Climate
• Various features of the landscape
– Contribute to local variations in climate

39. Bodies of Water
• Oceans and their currents, and large lakes
– Moderate the climate of nearby terrestrial
environments
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.

40. Mountains
• Mountains have a significant effect on
– The amount of sunlight reaching an area
– Local temperature
– Rainfall
Farther inland, precipitation
increases again as the air
moves up and over higher
mountains. Some of the world’s
deepest snow packs occur here.
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 world’s tallest
trees, the coastal redwoods,
thrive here.
1
2
East
Pacific
Ocean
Wind
direction
Coast
Range
Sierra
Nevada

41. Seasonality
• The angle of the sun
– Leads to many seasonal changes in local
environments

42. Microclimate
• Microclimate
– Is determined by fine-scale differences in abiotic
factors

43. Long-Term Climate Change
• One way to predict future global climate change
– Is to look back at the changes that occurred
previously
Current
range
Predicted
range
Overlap
(a) 4.5C warming over
next century
(b) 6.5C warming over
next century

44. • Abiotic and biotic factors influence the structure
and dynamics of aquatic biomes
• 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

45. • The examination of biomes will begin with
Earth’s aquatic biomes
30N
Tropic of
Cancer
Equator
30S
Continental
shelf
Lakes
Coral reefs
Rivers
Oceanic pelagic
zone
Estuaries
Intertidal zone
Abyssal zone
(below oceanic
pelagic zone)
Key
Tropic of
Capricorn

46. • 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

47. • Many aquatic biomes
– Are stratified into zones or layers defined by light
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 Limnetic
zone
Photic
zone
Benthic
zone
Aphotic
zone
Pelagic
zone
Intertidal zone
Neritic zone Oceanic zone
0
200 m
Continental
shelf
Photic zone
Pelagic
zone
Aphotic
zone
Benthic
zone
2,500–6,000 m
Abyssal zone
(deepest regions of ocean floor)
(b)

48. • Lakes
An oligotrophic lake in
Grand Teton, Wyoming
A eutrophic lake in Okavango
delta, Botswana
LAKES

49. • Wetlands
WETLANDS
Okefenokee National Wetland Reserve in Georgia

50. • Streams and rivers
STREAMS AND RIVERS
A headwater stream in the
Great Smoky Mountains
The Mississippi River far
form its headwaters

51. • Estuaries
An estuary in a low coastal plain of Georgia
ESTUARIES

52. • Intertidal zones
INTERTIDAL ZONES
Rocky intertidal zone on the Oregon coast

53. • Oceanic pelagic biome
Open ocean off the island of Hawaii
OCEANIC PELAGIC BIOME

54. • Coral reefs
A coral reef in the Red Sea
CORAL REEFS

55. • Marine benthic zone
A deep-sea hydrothermal vent community
MARINE BENTHIC ZONE

56. • Climate largely determines the distribution and
structure of terrestrial biomes
• Climate
– Is particularly important in determining why
particular terrestrial biomes are found in certain
areas

57. • The distribution of major terrestrial biomes
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

58. General Features of Terrestrial Biomes
• Terrestrial biomes
– Are often named for major physical or climatic
factors and for their predominant vegetation
• Stratification
– Is an important feature of terrestrial biomes

59. • Tropical forest
TROPICAL FOREST
A tropical rain forest in Borneo

60. • Desert
DESERT
The Sonoran Desert in southern Arizona

61. • Savanna
SAVANNA
A typical savanna in Kenya

62. • Chaparral
CHAPARRAL
An area of chaparral in California

63. • Temperate grassland
Sheyenne National Grassland in North Dakota
TEMPERATE GRASSLAND

64. • Coniferous forest
Rocky Mountain National Park in Colorado
CONIFEROUS FOREST

65. • Temperate broadleaf forest
TEMPERATE BROADLEAF FOREST
Great Smoky Mountains National Park in North Carolina

66. • Tundra
TUNDRA
Denali National Park, Alaska, in autumn

67. Ecosystems

68. • Overview: Ecosystems, Energy, and Matter
• An ecosystem consists of all the organisms living
in a community
– As well as all the abiotic factors with which they
interact

69. • Ecosystems can range from a microcosm, such
as an aquarium to a large area such as a lake or
forest

70. • Regardless of an ecosystem’s size
– Its dynamics involve two main processes: energy
flow and chemical cycling
• Energy flows through ecosystems
– While matter cycles within them

71. • Ecosystem ecology emphasizes energy flow and
chemical cycling
• Ecosystem ecologists view ecosystems
– As transformers of energy and processors of matter

72. Ecosystems and Physical Laws
• The laws of physics and chemistry apply to
ecosystems
– Particularly in regard to the flow of energy
• Energy is conserved
– But degraded to heat during ecosystem processes

73. Trophic Relationships
• Energy and nutrients pass from primary
producers (autotrophs)
– To primary consumers (herbivores) and then to
secondary consumers (carnivores)

74. • Energy flows through an ecosystem
– Entering as light and exiting as heat
Microorganisms
and other
detritivores
Detritus
Primary producers
Primary consumers
Secondary
consumers
Tertiary
consumers
Heat
Sun
Key
Chemical cycling
Energy flow

75. • Nutrients cycle within an ecosystem

76. Decomposition
• Decomposition
– Connects all trophic levels

77. • Bacteria and fungi, recycle essential chemical elements
– By decomposing organic material and returning
elements to inorganic reservoirs

78. • Physical and chemical factors limit primary
production in ecosystems
• Primary production in an ecosystem
– Is the amount of light energy converted to chemical
energy by autotrophs during a given time period

79. Ecosystem Energy Budgets
• The extent of photosynthetic production
– Sets the spending limit for the energy budget of the
entire ecosystem

80. The Global Energy Budget
• The amount of solar radiation reaching the
surface of the Earth
– Limits the photosynthetic output of ecosystems
• Only a small fraction of solar energy
– Actually strikes photosynthetic organisms

81. Gross and Net Primary Production
• Total primary production in an ecosystem
– Is known as that ecosystem’s gross primary
production (GPP)
• Not all of this production
– Is stored as organic material in the growing plants

82. • Net primary production (NPP)
– Is equal to GPP minus the energy used by the
primary producers for respiration
• Only NPP
– Is available to consumers

83. Primary Production in Marine and
Freshwater Ecosystems
• In marine and freshwater ecosystems
– Both light and nutrients are important in controlling
primary production

84. Light Limitation
• The depth of light penetration
– Affects primary production throughout the photic
zone of an ocean or lake

85. Nutrient Limitation
• More than light, nutrients limit primary
production
– Both in different geographic regions of the ocean
and in lakes

86. • A limiting nutrient is the element that must be
added
– In order for production to increase in a particular
area
• Nitrogen and phosphorous
– Are typically the nutrients that most often limit
marine production

87. • The addition of large amounts of nutrients to
lakes
– Has a wide range of ecological impacts

88. • In some areas, sewage runoff
– Has caused eutrophication of lakes, which can lead to
the eventual loss of most fish species from the lakes

89. • Biological and geochemical processes move
nutrients between organic and inorganic parts
of the ecosystem
• Life on Earth
– Depends on the recycling of essential chemical
elements
• Nutrient circuits that cycle matter through an
ecosystem
– Involve both biotic and abiotic components and are
often called biogeochemical cycles

90. A General Model of Chemical Cycling
• Gaseous forms of carbon, oxygen, sulfur, and
nitrogen
– Occur in the atmosphere and cycle globally
• Less mobile elements, including phosphorous,
potassium, and calcium
– Cycle on a more local level

91. • All elements
– Cycle between organic and inorganic reservoirs

92. Biogeochemical Cycles
• The water cycle and the carbon cycle
Transport
over land
Solar energy
Net movement of
water vapor by wind
Precipitation
over ocean
Evaporation
from ocean
Evapotranspiration
from land
Precipitation
over land
Percolation
through
soil
Runoff and
groundwater
CO2 in atmosphere
Photosynthesis
Cellular
respiration
Burning of
fossil fuels
and wood
Higher-level
consumers
Primary
consumers
Detritus
Carbon compounds
in water
Decomposition
THE WATER CYCLE THE CARBON CYCLE

93. • Water moves in a global cycle
– Driven by solar energy
• The carbon cycle
– Reflects the processes of photosynthesis and cellular
respiration

94. • The rates at which nutrients cycle in different
ecosystems
– Are extremely variable, mostly as a result of
differences in rates of decomposition

95. • The human population is disrupting chemical
cycles throughout the biosphere
• As the human population has grown in size
– Our activities have disrupted the trophic structure,
energy flow, and chemical cycling of ecosystems in
most parts of the world

96. Nutrient Enrichment
• In addition to transporting nutrients from one
location to another
– Humans have added entirely new materials, some of
them toxins, to ecosystems

97. Agriculture and Nitrogen Cycling
• Agriculture constantly removes nutrients from
ecosystems
– That would ordinarily be cycled back into the soil

98. • Nitrogen is the main nutrient lost through
agriculture
– Thus, agriculture has a great impact on the nitrogen
cycle
• Industrially produced fertilizer is typically used
to replace lost nitrogen
– But the effects on an ecosystem can be harmful

99. Contamination of Aquatic Ecosystems
• The critical load for a nutrient
– Is the amount of that nutrient that can be absorbed
by plants in an ecosystem without damaging it

100. • When excess nutrients are added to an
ecosystem, the critical load is exceeded
– And the remaining nutrients can contaminate
groundwater and freshwater and marine ecosystems

101. • Sewage runoff contaminates freshwater
ecosystems
– Causing cultural eutrophication, excessive algal
growth, which can cause significant harm to these
ecosystems

102. Acid Precipitation
• Combustion of fossil fuels
– Is the main cause of acid precipitation

103. • North American and European ecosystems downwind
from industrial regions
– Have been damaged by rain and snow containing nitric
and sulfuric acid
4.6
4.6
4.3
4.1
4.3
4.6
4.6
4.3
Europe
North America

104. • By the year 2000
– The entire contiguous United States was affected by acid
precipitation
Field pH
5.3
5.2–5.3
5.1–5.2
5.0–5.1
4.9–5.0
4.8–4.9
4.7–4.8
4.6–4.7
4.5–4.6
4.4–4.5
4.3–4.4
4.3

105. • Environmental regulations and new industrial
technologies
– Have allowed many developed countries to reduce
sulfur dioxide emissions in the past 30 years

106. Toxins in the Environment
• Humans release an immense variety of toxic
chemicals
– Including thousands of synthetics previously
unknown to nature
• One of the reasons such toxins are so harmful
– Is that they become more concentrated in
successive trophic levels of a food web

107. • In some cases, harmful substances
– Persist for long periods of time in an ecosystem and
continue to cause harm

108. Atmospheric Carbon Dioxide
• One pressing problem caused by human
activities
– Is the rising level of atmospheric carbon dioxide

109. Rising Atmospheric CO2
• Due to the increased burning of fossil fuels and other
human activities
– The concentration of atmospheric CO2 has been steadily
increasing
CO
2
concentration
(ppm)
390
380
370
360
350
340
330
320
310
300
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
1.05
0.90
0.75
0.60
0.45
0.30
0.15
0
0.15
 0.30
 0.45
Temperature
variation
(C)
Temperature
CO2
Year

110. How Elevated CO2 Affects Forest Ecology:
The FACTS-I Experiment
• The FACTS-I experiment is testing how elevated CO2
– Influences tree growth, carbon concentration in soils, and
other factors over a ten-year period

111. The Greenhouse Effect and Global
Warming
• The greenhouse effect is caused by atmospheric
CO2
– But is necessary to keep the surface of the Earth at a
habitable temperature

112. • Increased levels of atmospheric CO2 are
magnifying the greenhouse effect
– Which could cause global warming and significant
climatic change

113. • Satellite studies of the atmosphere
– Suggest that the ozone layer has been gradually thinning
since 1975
Ozone
layer
thickness
(Dobson
units)
Year (Average for the month of October)
350
300
250
200
150
100
50
0
1955 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005

114. Depletion of Atmospheric Ozone
• Life on Earth is protected from the damaging
effects of UV radiation
– By a protective layer or ozone molecules present in
the atmosphere

115. • The destruction of atmospheric ozone
– Probably results from chlorine-releasing pollutants
produced by human activity
1
2
3
Chlorine from CFCs interacts with ozone (O3),
forming chlorine monoxide (ClO) and
oxygen (O2).
Two ClO molecules
react, forming
chlorine peroxide (Cl2O2).
Sunlight causes
Cl2O2 to break
down into O2
and free
chlorine atoms.
The chlorine
atoms can begin
the cycle again.
Sunlight
Chlorine O3
O2
ClO
ClO
Cl2O2
O2
Chlorine atoms

116. • Scientists first described an “ozone hole”
– Over Antarctica in 1985; it has increased in size as
ozone depletion has increased
(a) October 1979 (b) October 2000

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