1. Ecology of Organisms and Populations
Ch. 18

2. Ecology Study of interactions between organisms and their environment
Ecology can be divided into four increasingly comprehensive levels:
Organismal ecology
Population ecology
Community ecology
Ecosystem ecology

3. Ecology Organismal ecology
Is concerned with evolutionary adaptations that enable individual organisms to meet the challenges posed by their abiotic environments.

4. Ecology Population ecology
Is concerned with populations, groups of individuals of the same species living in the same area.
Concentrates mainly on factors that affect population density and growth.

5. Ecology Community ecology
Is concerned with communities, assemblages of populations of different species.
Focuses on how interactions between species affect community structure and organization.

6. Ecology Ecosystem ecology
Is concerned with ecosystems, which include 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.

7. Components of the Environment
The abiotic component
Consists of nonliving chemical and physical factors.
The biotic component
Includes the living factors.

8. Abiotic Factors of the Biosphere
On a global scale, ecologists have recognized striking regional patterns in the distribution of terrestrial and aquatic life.
Global distribution patterns
Reflect regional differences in climate and other abiotic factors.

9. Sunlight Solar energy powers nearly all ecosystems.
Availability of sunlight affects aquatic and terrestrial environments.

10. Water Aquatic organisms may face problems with water balance.
For terrestrial organisms, the main water problem is drying out.

11. Temperature Environmental temperature
Is an important abiotic factor because of its effect on metabolism.

12. Wind Some organisms depend on nutrients blown to them by wind.
Organisms such as plants depend on wind to disperse pollen and seeds.
Can also affect the pattern of a plant’s growth.

13. Rocks and Soil
Soil variation contributes to the patchiness we see in terrestrial landscapes.
In streams and rivers, the composition of the soil can affect water chemistry.

14. Periodic Disturbances
Catastrophic disturbances
Can devastate biological communities.
After a disturbance,
An area is recolonized by organisms, or repopulated by survivors.
The structure of the community undergoes a succession of changes during the rebound.

15. Ecosystems
What biotic and abiotic factors do you see in this picture of the rain forest?
Biotic: Trees, moss growing on the rocks, insects and other animals living in the trees, maybe fish in the stream.
Abiotic: Sunlight (needed for the plant life), rocks (for the moss to grow on), temperature, humidity, etc.

16. Ecosystems
What biotic and abiotic factors do you see in this picture of a tundra?
Biotic: Grasses, insects living underground, a few trees, other animals that live here
Abiotic: Snow, cold temperatures, rocky terrain, etc.

17. Ecosystems
What biotic and abiotic factors do you see in this picture of our study area?
Biotic: Grasses, insects living underground, a few trees, other animals that live here
Abiotic: Snow, cold temperatures, rocky terrain, etc.

18. Creek Ecology Delegate duties Paint the picture…
Start collecting samples to use in your study.
Field Guides are available.
Homework tonight: Define Bold terms in What is Population Ecology? Section pages Have checked Wednesday. Pick one term and relate to our study site on Edmodo. Post by Wednesday.

19. Presenting your data… Using the tree data for example Data Charts
Species:
Circumference (m)
DBH (m) = circumference/pi
Basal Area (m2) = (DBH)2

20. Then summarize your data in another table…
Species
Total No. of Individuals
Density
Relative Density
Total Basal Area
Dominance
Relative Dominance
Importance Value

21. Populations A population is… Members of the same species…
Who live in the same place
At the same time.

22. Populations
The environment where a population lives: habitat.

23. Populations
Population ecologists study many things about populations in their habitats:
Population size
Population density
Population growth

24. Population Density Population density
Is the number of individuals of a species per unit of area or volume.
In most cases, it is impractical or impossible to count all individuals in a population.
In some cases, population densities are estimated by indirect indicators, such as number of bird nests or rodent burrows.

25. Populations
Populations are densest where there are resources available.

26. Populations

27. Patterns of Dispersion
The dispersion pattern of a population is the way individuals are spaced within the population’s geographic range.

28. Clumped Pattern of Dispersion
Individuals aggregate in patches.

29. Uniform Pattern of Dispersion
Results from interactions among the individuals of a population.

30. Random Pattern of Dispersion
Individuals are spaced in a patternless, unpredictable way.

31. Estimating Population Size activity
Estimating Population Size Check

32. Homework
Study. Quiz on Notes and Population Size Estimates Wednesday.

33. Pitfall Trap
How to build an insect pitfall trap

34. Population Growth Models
Two models, the exponential growth model and the logistic growth model, will help us understand population growth.
The growth rate
Is the change in population size per time interval.

35. The Exponential Growth Model: The Ideal of an Unlimited Environment
Describes the rate of expansion of a population under ideal, unregulated conditions.

36. The Exponential Growth Model: The Ideal of an Unlimited Environment
A key feature of the exponential growth model is that the rate at which a population grows depends on the number of individuals already in the population.

37. The Logistic Growth Model: The Reality of a Limited Environment
In nature, a population may grow exponentially for a while, but eventually one or more environmental factors will limit its growth.
Population-limiting factors restrict population growth.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings

38. The Logistic Growth Model: The Reality of a Limited Environment
Describes growth of an idealized population that is slowed by limiting factors.

39. A comparison of the logistic growth model and the exponential growth model

40. Carrying Capacity
Is the number of individuals in a population that the environment can just maintain with no net increase or decrease.

41. Regulation of Population Growth
Density-Dependent Factors
Are population-limiting factors whose effects intensify as the population increases in size.
Increase a population’s death rate and decrease the birth rate.

42. Regulation of Population Growth
Density-independent factors
Are population-limiting factors whose intensity is unrelated to population density.
Include events such as seasonal freezing.
In many natural populations, density-independent factors limit population size before density-dependent factors become important.

43. Growth Rate Four influences: Birth + Immigration – Death – Emigration
Birth rate 
Death rate 
Immigration 
Emigration 
Birth + Immigration – Death – Emigration
Density-dependent: Food, water, mates
Density-independent: Heat, drought, temperature swings

44. Population Cycles Some populations Have regular boom-and-bust cycles.
Boom-and-bust cycles of the snowshoe hare and one of its predators, the lynx

45. Answer the following questions:
What two types of growth models are there? What’s the difference?
What four things are considered in Growth Rate?
Name an example of a density dependent limiting factor.
Density-independent limiting factor?

46. How many People can live on Planet Earth?
Population Growth activity.
Finish for homework.
Answer questions. Complete #5 and to me.

47. Communities and Ecosystems
Ch. 19

48. Key Properties of Communities
Diversity—variety of different kinds of organisms that make it up
Prevalent form of vegetation—determines kinds of organisms that will survive in the area
Stability—ability to resist change and return to its original species composition after being disturbed
Trophic level—feeding relationships among the various species

49. Diversity The diversity of a community
Which community is more diverse?
The diversity of a community
Is the variety of different kinds of organisms that make up the community.
Species richness, the total number of different species in the community
Relative abundance of the different species

50. Interactions Between Populations of Different Species
Interspecific interactions—occur b/w populations of different species
Coevolution—a change in one species acts as a selective force on another species

51. Interspecific Competition
Competition occurs when 2 or more populations overlap in their niches
Limiting resources
Food
Space
Mates
Generally, one will out-compete the other

52. Competition in Nature Two possible Outcomes
Weaker competitor becomes extinct
One or both species may evolve enough to use a different set of resources (resource partitioning)
Competition cannot operate for long periods of time

53. Competitive Exclusion Principle
Two species cannot coexist in a community if their niches are identical

54. Joseph H. Connell Study

55. Interactions Between Populations of Different Species
Predation—consumption of one organism by another
Parasitism—specialized predator (parasite) lives on/in its host, not killed immediately
Endoparasitism—live inside host (tapeworms/viruses)
Ectoparasitism—live on surface
of host (mosquitoes/aphids)
Herbivory—herbivores
consume plants

56. Predator and Prey Relationships
Great Whites
Interspecific competition

57. Predator Adaptations Most predators have acute senses. Many predators
Have adaptations such as claws, teeth, fangs, stingers, or poison to help catch and subdue prey.
Are fast and agile.

58. Plant Defenses Against Hebivores
Physical defenses
thorns, hooks/spines on leaves
Chemical defenses
Make plant distasteful or poisonous
Morphine from opium poppy
Nicotine from tobacco
Poison Ivy

59. Animal Defenses Against Predators
Behavioral defenses
Alarm cries
Distraction displays
Cryptic coloration/shape
(camouflage)
Blend in with environment
Asposematic coloration
Red/black; yellow/black
Mechanical/chemical defenses
Quills, spines, and other similar structures
Toxins—distasteful or poisonous
Stick Insect
Monarch butterfly on Milkweed

60. Animal Defenses Against Predators
Mimicry—prey resembles species that cannot be eaten
Batesian mimicry: Imitate color patterns or appearance of more dangerous/unpalatable organisms
Müllerian mimicry: 2 unpalatable species that inhabit the same community mimic each other

61. Animal Defenses Against Predators
Mimicry can be used to lure prey
Snapping turtle wriggles tongue like a worm to attract and capture small fish
Angler Fish attract prey close enough to their mouths to be easily grabbed
defense against predators

62. Symbiotic Relationships
Non-Beneficial
Parasitism—host harmed
Beneficial
Mutualism—both partners benefit
Lichens-association b/w fungus and algae
Nitrogen-fixing bacteria and legumes
Caribbean Cleaner

63. Figure: 23.21
Title:
Nitrogen fixation in legumes
Caption:
A diagram and photograph of root nodules, containing nitrogen-fixing bacteria, in legumes.

64. Community Structure
Predators can moderate competition among its prey species
Keystone species can alter the whole community

65. Community Structure
Lake Davis, CA
Introduction of a species (exotic species) into a community can have drastic affects on the existing community members
Northern Pike

66. Disturbances in a Community
Storms, fire, floods, droughts, overgrazing, or detrimental human activities:
Remove organisms
Alter resource availability
Create opportunities for new species that have not previously occupied the habitat
Humans are the biggest disturbance
Logging, agriculture, overgrazing

67. Ecological Succession
Primary succession
Begins in a virtually lifeless area where soil has not formed
Lichens and mosses colonize first
Soil gradually forms and small plants and shrubs take root
Secondary succession
Occurs where an existing community has been cleared by some disturbance that leaves soil in tact
Earliest plants to recolonize are often those that grow from wind-blown or animal-borne seeds

68. Ecological Succession
Tolerance to abiotic conditions determines early species
Competition among early species shape the succession of an area

69. Mt. St. Helen 1980 Eruption
MSH80_st_helens_spirit_lake_before_may_18_1980.jpg

70. Mt. St. Helen Secondary Succession
Red alder disperses easily and is capable of rapid growth on the nutrient-poor, volcanic deposits.
A red-legged frog –one of the creatures living in one of the dozens of ponds created after the eruption.
70 species of birds, including hummingbirds, western meadowlarks and Savannah sparrows

71. An Overview of Ecosystem Dynamics
An ecosystem
Is a biological community and the abiotic factors with which the community interacts.
Energy flow
Is the passage of energy through the components of the ecosystem.
Chemical cycling
Is the use and reuse of chemical elements within the ecosystem.

72. Crash Course

73. Energy Flows through an ecosystem when consumers feed on producers.
Cannot be recycled within an ecosystem, but must flow through continuously.

74. Ecosystem Dynamics Energy flow and chemical cycling
Depend on the transfer of substances in the feeding relationships, or trophic structure, of an ecosystem.
Trophic relationships
Determine an ecosystem’s routes of energy flow and chemical cycling.
Trophic levels
Divide the species of an ecosystem based on their main sources of nutrition.

75. Trophic Relationships
Ecosystems divided into trophic levels (feeding levels)
Producers—autotrophs (mostly photosynthetic)
Primary consumers—herbivores
Secondary consumers—carnivores that eat herbivores
Tertiary consumers—carnivores that eat other carnivores
Detrivores—consumers that eat dead or decaying matter

76. Food Chain/Food Web

77. Energy Flow in Ecosystems
Each level in a food web contains a different quantity of stored chemical energy
When consumers eat producers or 2 consumers eat 1 consumers, some energy is lost in each transfer from one level to the next

78. Energy pyramid
A diagram that represents the cumulative loss of energy from a food chain.

79. Simulate Energy Flow through an ecosystem.

80. Chemical Cycling in Ecosystems
Depend on a recycling of chemical elements.
Biogeochemical cycles
Are chemical cycles in an ecosystem that involve both biotic and abiotic components.

81. Biogeochemical Cycles
Three key points :
Each circuit has an abiotic reservoir.
A portion of chemical cycling can rely completely on geological processes.
Some chemicals require processing before they are available as inorganic nutrients.

82. Examples of Biogeochemical Cycles
Carbon
Nitrogen
Phosphorus
Water

83. Carbon Cycle Human Impacts: Greenhouse Effect
Increase of atmospheric CO2
Combustion of fossil fuels
Burning of wood from deforestation
Increase in global temperature

84. Nitrogen Cycle Human Impact:
Cultivation—turns up soil and ↑ decomposition of organic matter; Releases more nitrogen
Harvesting ↓ nitrogen from ecosystem
Adding industrially synthesized fertilizers to soil has resulted in doubling globe’s supply
Excess nitrogen leeches into soil and into rivers, streams, and lakes and ground water—
↑ levels are toxic to aquatic organisms and humans
Algal blooms in lakes ↑ eutrophication

85. Phosphorus Cycle Human Impact:
Sewage treatment facilities and fertilizers
↑ amounts of phosphates to aquatic systems, causing eutrophication of lakes.

86. Water Cycle Human Impact: Destruction of tropical rain forest
Will change the amount of water vapor in the air.
May alter local and global weather patterns.
To irrigate crops, humans pump large amounts of ground water to the surface.

87. Avatar Project

88. Human Impact You have been given a Post It with a question.
Read your question and tell the group the research you did to answer the question.
Bees Ted Talk
Relate your discussion and the Ted Talk back to our Avatar Study.

89. Review for Ecosystem/Human Impact Test
The test will consist of:
Multiple Choice
Short Answer
Biodiversity and Succession Essay
Discussion of ecological relationships.