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Chapter 15: Ecosystems and
Communities
Organisms and their environments
by Mark Manteuffel, St. Louis Community College
What are ecosystems?
 A community of biological organisms plus
the non-living components with which the
organisms interact
Take-home message
 An ecosystem is all of the living organisms
in a habitat as well as the physical
environment.
 Ecosystems are found not just in obvious
places such as ponds, deserts, and
tropical rainforests but also in some
unexpe...
A variety of biomes occur
around the world, each
determined by temperature
and rainfall.
Biomes
 What is the average temperature?
 What is the average rainfall (or other
precipitation)?
 Is the temperature re...
Biomes
 Temperature and precipitation dictate:
• Primary productivity levels
 the amount of organic matter produced
 Th...
Take-home message
 Biomes are the major ecological
communities of earth, characterized
mostly by the vegetation present.
...
Global air circulation
patterns create deserts and
rainforests.
Take-home message
 Global patterns of weather are largely
determined by the earth’s round shape.
 Solar energy hits the ...
 This temperature gradient generates
atmospheric circulation patterns that result
in heavy rain at the equator and many
d...
Local topography
influences the weather.
Is it warmer or cooler in urban
areas relative to nearby rural
areas?
“Urban Heat Islands”
Why is it so windy on streets
with tall buildings?
Take-home message
 Local features of topography influence the
weather.
 With higher altitude, the temperature drops.
 O...
 Urban development increases the
absorption of solar energy, leading to
higher temperatures, and creates wind
near the bo...
Ocean currents affect the
weather.
Global Patterns of Circulation in
the Oceans
Why do beach communities
have milder weather than more
inland communities?
Water’s Capacity to Absorb and Hold Heat
Take-home message
 Oceans have global circulation patterns.
 Disruptions in these patterns occur every
few years and can...
Energy flows
from producers to
consumers.
First Stop: Primary Producers
Second Stop: Primary
Consumers—the Herbivores
Third Stop: Secondary Consumers—
the Carnivores
Fourth Stop: Tertiary Consumers—the
“Top” Carnivores
Chains or Webs?
 Food chain
• Pathway from photosynthetic producers
through the various levels of animals
 Food web
• In...
Energy Flows
 Losses at every “step” in a food chain
 Inefficiency of energy transfers
Take-home message
 Energy from the sun passes through an
ecosystem in several steps.
 First, it is converted to chemical...
Take-home message
 Herbivores then consume the primary
producers, the herbivores are consumed
by carnivores, and the carn...
Take-home message
 Detritivores and decomposers extract
energy from organic waste and the
remains of organisms that have ...
Energy pyramids reveal the
inefficiency of food chains.
10% Efficiency
Biomass
 10% rule
 Where does the rest go?
 Expended in cellular respiration or lost as
feces
Why are big, fierce animal
species so rare in the world?
Take-home message
 Energy from the sun passes through an
ecosystem in several steps known as
trophic levels.
 Energy pyr...
Take-home message
 The biomass transferred at each step
along the food chain tends to be only
about 10% of the biomass of...
Essential chemicals cycle
through ecosystems.
The Recycling of Molecules
Chemical Reservoirs
 Each chemical is stored in a non-living part of
the environment.
 Organisms acquire the chemical fr...
The Three Most Important
Chemical Cycles
1) Carbon
2) Nitrogen
3) Phosphorus
Why are global CO2 levels
rising?
Fossil Fuels
Global CO2 levels are rising in
general, but they also exhibit a sharp
rise and fall within each year.
Why?
Nitrogen is like a bottleneck
limiting plant growth.
Fertilizers
Take-home message
 Chemicals essential to life—including carbon,
nitrogen, and phosphorus—cycle through
ecosystems.
Take-home message
They are usually captured from the
atmosphere, soil, or water by growing
organisms; passed from one tro...
Take-home message
 These cycles can be disrupted as human
activities significantly increase the
amounts of the chemicals ...
Interacting species evolve together.
Natural Selection
 Causes organisms to become better
adapted to their environment
 Does not distinguish between biotic a...
Take-home message
 In producing organisms better adapted to
their environment, natural selection does
not distinguish bet...
Each species’ role in a
community is defined by its
niche.
More than just a place for living, a niche is a
complete way of living.
“You can’t always get what you want.”
 Fundamental niche
• the full range of environmental conditions
under which a speci...
Take-home message
 A population of organisms in a community
fills a unique niche, defined by the manner
in which they uti...
Competition can be hard to see,
but it still influences community
structure.
Take-home message
 Populations with completely overlapping
niches cannot coexist forever.
 Competition for resources occ...
Predation produces
adaptation in both predators
and their prey.
Predation
 One of the most important forces shaping
the composition and abundance of
species in a community
Why do exotic species often flourish
when released into novel habitats,
even though natural selection has not
adapted them...
Prey Adaptations for Reducing
Predation
 There are two broad categories of
defenses against predators:
• Physical
• Behav...
Physical Defenses
Include Mechanical, Chemical,
Warning Coloration, and
Camouflage Mechanisms
1) Mechanical Defenses
2) Chemical Defenses
3) Warning Coloration
4) Camouflage
Behavioral Defenses
Include both seemingly passive
and active behaviors: hiding or
escaping, or alarm calling or
fighting ...
Predator adaptations for
enhancing predation
Take-home message
 Predators and their prey are in an
evolutionary arms race.
 As physical and behavioral features
evolv...
Take-home message
 The coevolutionary process can result in
brightly colored organisms, alarm calling,
and many types of ...
Parasitism is a form of
predation.
Parasite Predators
 Parasites have some unique features and
face some unusual challenges:
• The parasite generally is muc...
Case 1: Parasites can induce foolish,
fearless behavior in their hosts.
 Toxoplasma
 Rats and cats
Case 2: Parasites can induce inappropriate
aggression in their hosts.
Case 3: Parasites can induce bizarre
and risky behavior in their hosts.
 The lancet fluke
Take-home message
 Parasitism is a symbiotic relationship in
which one organism benefits while the
other is harmed.
 Par...
Not all species interactions are
negative: mutualism and
commensalism.
Take-home message
 Not all species interactions are combative.
 Evolution produces beneficial species
interactions as we...
Many communities change
over time.
Secondary Succession
 Much faster than primary succession
• life and soil are already present
Take-home message
 Succession is the change in the species
composition of a community over time,
following a disturbance....
Take-home message
 In secondary succession, the process
occurs in an area where life is already
present.
 But in both ty...
Some species are more
important than others within a
community.
Take-home message
 Keystone species have a relatively large
influence on which other species are
present in a community a...
Take-home message
• Unlike other species, when a keystone
species is removed from the community, the
species mix changes d...
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Community ecosystem ecology_access(1)

  1. 1. Chapter 15: Ecosystems and Communities Organisms and their environments by Mark Manteuffel, St. Louis Community College
  2. 2. What are ecosystems?  A community of biological organisms plus the non-living components with which the organisms interact
  3. 3. Take-home message  An ecosystem is all of the living organisms in a habitat as well as the physical environment.
  4. 4.  Ecosystems are found not just in obvious places such as ponds, deserts, and tropical rainforests but also in some unexpected places, like the digestive tracts of organisms or the shell of a beetle. Take-home message
  5. 5. A variety of biomes occur around the world, each determined by temperature and rainfall.
  6. 6. Biomes  What is the average temperature?  What is the average rainfall (or other precipitation)?  Is the temperature relatively constant or does it vary seasonally?  Is the rainfall relatively constant or does it vary seasonally?
  7. 7. Biomes  Temperature and precipitation dictate: • Primary productivity levels  the amount of organic matter produced  The numbers and types of primary producer: • are the chief determinants of the amount and breadth of other life in the region.
  8. 8. Take-home message  Biomes are the major ecological communities of earth, characterized mostly by the vegetation present.  Different biomes result from differences in temperature and precipitation, and the extent to which they vary from season to season.
  9. 9. Global air circulation patterns create deserts and rainforests.
  10. 10. Take-home message  Global patterns of weather are largely determined by the earth’s round shape.  Solar energy hits the equator at a more direct angle than at the poles, leading to warmer temperatures at lower latitudes.
  11. 11.  This temperature gradient generates atmospheric circulation patterns that result in heavy rain at the equator and many deserts at 30° latitude. Take-home message
  12. 12. Local topography influences the weather.
  13. 13. Is it warmer or cooler in urban areas relative to nearby rural areas? “Urban Heat Islands”
  14. 14. Why is it so windy on streets with tall buildings?
  15. 15. Take-home message  Local features of topography influence the weather.  With higher altitude, the temperature drops.  On the windward side of mountains, rainfall is high; on the backside, descending air reduces rainfall, causing rain shadow deserts.
  16. 16.  Urban development increases the absorption of solar energy, leading to higher temperatures, and creates wind near the bottom of tall buildings. Take-home message
  17. 17. Ocean currents affect the weather. Global Patterns of Circulation in the Oceans
  18. 18. Why do beach communities have milder weather than more inland communities? Water’s Capacity to Absorb and Hold Heat
  19. 19. Take-home message  Oceans have global circulation patterns.  Disruptions in these patterns occur every few years and can cause extreme climate disruptions around the world.
  20. 20. Energy flows from producers to consumers.
  21. 21. First Stop: Primary Producers
  22. 22. Second Stop: Primary Consumers—the Herbivores
  23. 23. Third Stop: Secondary Consumers— the Carnivores
  24. 24. Fourth Stop: Tertiary Consumers—the “Top” Carnivores
  25. 25. Chains or Webs?  Food chain • Pathway from photosynthetic producers through the various levels of animals  Food web • Involve harvesting energy from multiple stops in the food chain
  26. 26. Energy Flows  Losses at every “step” in a food chain  Inefficiency of energy transfers
  27. 27. Take-home message  Energy from the sun passes through an ecosystem in several steps.  First, it is converted to chemical energy in photosynthesis.
  28. 28. Take-home message  Herbivores then consume the primary producers, the herbivores are consumed by carnivores, and the carnivores, in turn, may be consumed by top carnivores.
  29. 29. Take-home message  Detritivores and decomposers extract energy from organic waste and the remains of organisms that have died.  At each step in a food chain, some usable energy is lost as heat.
  30. 30. Energy pyramids reveal the inefficiency of food chains. 10% Efficiency
  31. 31. Biomass  10% rule  Where does the rest go?  Expended in cellular respiration or lost as feces
  32. 32. Why are big, fierce animal species so rare in the world?
  33. 33. Take-home message  Energy from the sun passes through an ecosystem in several steps known as trophic levels.  Energy pyramids reveal that the biomass of primary producers in an ecosystem tends to be far greater than the biomass of herbivores.
  34. 34. Take-home message  The biomass transferred at each step along the food chain tends to be only about 10% of the biomass of the organisms being consumed, due to energy lost in cellular respiration.  As a consequence of this inefficiency, food chains rarely exceed four levels.
  35. 35. Essential chemicals cycle through ecosystems. The Recycling of Molecules
  36. 36. Chemical Reservoirs  Each chemical is stored in a non-living part of the environment.  Organisms acquire the chemical from the reservoir.  The chemical cycles through the food chain.  Eventually, the chemical is returned to the reservoir.
  37. 37. The Three Most Important Chemical Cycles 1) Carbon 2) Nitrogen 3) Phosphorus
  38. 38. Why are global CO2 levels rising? Fossil Fuels
  39. 39. Global CO2 levels are rising in general, but they also exhibit a sharp rise and fall within each year. Why?
  40. 40. Nitrogen is like a bottleneck limiting plant growth. Fertilizers
  41. 41. Take-home message  Chemicals essential to life—including carbon, nitrogen, and phosphorus—cycle through ecosystems.
  42. 42. Take-home message They are usually captured from the atmosphere, soil, or water by growing organisms; passed from one trophic level to the next as organisms eat other organisms; and returned to the environment through respiration, decomposition, and erosion.
  43. 43. Take-home message  These cycles can be disrupted as human activities significantly increase the amounts of the chemicals utilized or released to the environment.
  44. 44. Interacting species evolve together.
  45. 45. Natural Selection  Causes organisms to become better adapted to their environment  Does not distinguish between biotic and abiotic resources as selective forces
  46. 46. Take-home message  In producing organisms better adapted to their environment, natural selection does not distinguish between biotic and abiotic resources as selective forces.
  47. 47. Each species’ role in a community is defined by its niche.
  48. 48. More than just a place for living, a niche is a complete way of living.
  49. 49. “You can’t always get what you want.”  Fundamental niche • the full range of environmental conditions under which a species can live  Realized niche • where and how a species is actually living
  50. 50. Take-home message  A population of organisms in a community fills a unique niche, defined by the manner in which they utilize the resources in their environment.  Organisms do not always completely fill their niche; competition with species that have overlapping niches can reduce their range.
  51. 51. Competition can be hard to see, but it still influences community structure.
  52. 52. Take-home message  Populations with completely overlapping niches cannot coexist forever.  Competition for resources occurs until one or both species evolve in ways that reduce the competition, through character displacement, or until one becomes extinct in that location.
  53. 53. Predation produces adaptation in both predators and their prey.
  54. 54. Predation  One of the most important forces shaping the composition and abundance of species in a community
  55. 55. Why do exotic species often flourish when released into novel habitats, even though natural selection has not adapted them to this new environment?
  56. 56. Prey Adaptations for Reducing Predation  There are two broad categories of defenses against predators: • Physical • Behavioral
  57. 57. Physical Defenses Include Mechanical, Chemical, Warning Coloration, and Camouflage Mechanisms
  58. 58. 1) Mechanical Defenses
  59. 59. 2) Chemical Defenses
  60. 60. 3) Warning Coloration
  61. 61. 4) Camouflage
  62. 62. Behavioral Defenses Include both seemingly passive and active behaviors: hiding or escaping, or alarm calling or fighting back
  63. 63. Predator adaptations for enhancing predation
  64. 64. Take-home message  Predators and their prey are in an evolutionary arms race.  As physical and behavioral features evolve in prey species to reduce their predation risk, predators develop more effective and efficient methods of predation.
  65. 65. Take-home message  The coevolutionary process can result in brightly colored organisms, alarm calling, and many types of mimicry.
  66. 66. Parasitism is a form of predation.
  67. 67. Parasite Predators  Parasites have some unique features and face some unusual challenges: • The parasite generally is much smaller than its host and stays in contact with the host for extended periods of time. • Complicated life cycles as means of getting from host to host.
  68. 68. Case 1: Parasites can induce foolish, fearless behavior in their hosts.  Toxoplasma  Rats and cats
  69. 69. Case 2: Parasites can induce inappropriate aggression in their hosts.
  70. 70. Case 3: Parasites can induce bizarre and risky behavior in their hosts.  The lancet fluke
  71. 71. Take-home message  Parasitism is a symbiotic relationship in which one organism benefits while the other is harmed.  Parasites face some unusual challenges relative to other predators, particularly how to get from one individual host to another, and some complex parasite life cycles have evolved.
  72. 72. Not all species interactions are negative: mutualism and commensalism.
  73. 73. Take-home message  Not all species interactions are combative.  Evolution produces beneficial species interactions as well, including mutualism, in which both species benefit from the interaction, and commensalism, in which one species benefits and the other is neither harmed nor helped.
  74. 74. Many communities change over time.
  75. 75. Secondary Succession  Much faster than primary succession • life and soil are already present
  76. 76. Take-home message  Succession is the change in the species composition of a community over time, following a disturbance.  In primary succession, the process begins in an area with no life present.
  77. 77. Take-home message  In secondary succession, the process occurs in an area where life is already present.  But in both types, the process usually takes place in a predictable sequence.
  78. 78. Some species are more important than others within a community.
  79. 79. Take-home message  Keystone species have a relatively large influence on which other species are present in a community and which are not.
  80. 80. Take-home message • Unlike other species, when a keystone species is removed from the community, the species mix changes dramatically. • For this reason, preserving keystone species is an important strategy in maximizing the preservation of biodiversity.

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