1. Principles of Ecology
Unit 5

2. ECOLOGY WARM-UP
Put the following in order from smallest to 
largest:ecosystem, biome, organism, 
population, community, biosphere

3. Ecosystem Assignment
Draw a picture of your "ideal" ecosystem. In other words, if you could live in 
anywhere in the world, where would it be and what would it look like. List the biotic 
and abiotic factors around you. Also, write down the levels of organization in your 
ecosystem. (organism, population, community, ecosystem, biome)

5. What is Ecology?
Ecology is the study of the interactions among living things, 
and between living things and their surroundings.
Biologically_Speaking__Ecosystems_and_the_Cycles_of_Nature.asf

6. Levels of Organization
An 
organism is any 
living 
thing.
Ex: an 
alligator

7. A population is a group of the same species that lives in one area.
Ex: a group of 
alligators that 
live in the 
same place at 
the same time.
Population
Organism

8. A community is a group of different species that live together in 
one area.
Ex: alligators, birds, frogs, grass, trees, insects, etc…

9. An ecosystem includes all of the organisms as well as the climate, 
soil, water, rocks and other nonliving things in a given area
Ecosystem

10. A biome is a major regional or global community of organisms 
characterized by the climate conditions and plant communities that 
thrive there
Ex: Savanna

11. Biotic Factors: are the living things in a ecosystem. Examples:
Every ecosystem includes both living 
and nonliving factors:
Biotic Factors: are the living things in a ecosystem.
Examples:
Plants, animals, fungi,
bacteria, and protists

12. Abiotic Factors are the nonliving things in an ecosystem.
Examples: rainfall, temperature, sunlight, soil, & wind

13. Biodiversity is the assortment, or variety, of living things 
 in an ecosystem.
A keystone species is a species that has an unusually 
 large effect on an ecosystem.
Ex: Beavers lead to major changes in an ecosystem.

14. ENERGY IN ECOSYSTEMS

15. Producers and Consumers
Type
Also Called
Description
Producer
Autotroph
Gets energy from nonliving 
resources
Consumers
Heterotrophs
Get energy by eating other 
organisms

16. Processes by Which Produces Obtain Energy
Both:
All producers
make own 
energy

17. -Example of cyanobacteria

18. Types of Consumers Name of Consumer: Role: Herbivore Eats only plants
Carnivore Eats only other animals
Omnivore Eats both plants and animals
Detritivore Eats dead organic matter
(Examples: decomposers & scavengers)
Examples of each???
decomposer
carnivore

19. A food chain 
is a model that 
shows a 
sequence of 
feeding 
relationships.
*Trophic 
level s are the 
nourishment 
levels of a 
food chain.

20. Producer: phytoplankton & algae
Food Webs
A food web shows the complex network of 
feeding relationships and flow of energy.
Example in notes:
Producer: phytoplankton & algae
Primary Consumer: zooplankton, shrimp, etc…
Secondary Consumer: sponge, jellyfish
Tertiary Consumer: Reef Shark

22. Pyramid Models
Energy 
pyramid 
shows the 
distribution of 
energy among 
trophic levels
Tertiary 
Consumer
Secondary 
Consumer
Primary 
Consumer
Producers

23. Between each tier of an energy pyramid, up to 90 percent of the 
energy is lost into the atmosphere as heat.
Only 10 percent of the energy at each tier is transferred from one 
trophic level to the next.

24. Two other pyramid models:
1. Biomass Pyramid:
  measures: total dry mass of 
organisms in a given area.
tertiary
consumers
secondary
primary
producers
75 g/m2
150g/m2
675g/m2
2000g/m2

25. Measures: the number of individuals at each trophic level
2. Pyramid of Numbers:
Measures: the number of 
individuals at each trophic level
*Numbers in populations decrease as 
you go up. 5
5000

26. INTERACTIONS IN ECOSYSTEMS
A habitat is the place 
where an organism 
lives.

27. *A niche is an organism’s role in its environment.
*A niche includes all of the factors that a species needs to survive, stay healthy, and 
reproduce.
food
abiotic conditions
Behavior
Ecological equivalents are species that occupy 
similar niches but live in different geographical 
regions
Mad
agas
car
South 
Ameri
ca

28. Community Interactions
Important 
organism 
interactions 
include 
competition, 
symbiosis, and 
predation.
Symbiosis.asf

29. Competition Competition occurs when two organisms fight for the
same limited 
resource

30. Symbiosis
Symbiosis: relationship 
between 2 
different 
species where 
at least one 
species 
benefits.

31. Predation
-Predation
Process by which 
one organism 
hunts and kills 
another organism 
for food.

32. Types of Symbiotic Relationships
*Mutualism is a symbiotic 
relationship in 
which both 
species benefit.

33. Commensalism
One species 
benefits and 
the other is 
not affected.

34. Parasitism
Organism 
benefits _
Organism is not 
affected
Hornworm 
caterpillar
The host 
hornworm 
will 
eventually 
die as its 
organs are 
consumed
by wasp 
larvae.
Braconid 
wasp
Braconid 
larvae 
feed on 
their host 
and 
release 
themselve
s shortly 
before 
reaching
the pupae 
stage of 
developm
ent.
Parasitis
m +
Parasitism is a symbiotic 
relationship in 
which one species 
benefits and the 
other is harmed.

35. ECOLOGICAL SUCCESSION
*Ecosystems are always changing due to natural events or by human action.
*After any disturbance, organisms replace other 
species through the gradual, predictable process of
succession.
*Ecological succession is the natural replacement, over time, of one community of organisms by 
another. . -

36. PRIMARY SUCCESSION:
Primary succession is the gradual 
development of a 
new community from 
nothing..
*It occurs on bare terrain, 
without soil or pre-existing 
plant or animal life.)
*Volcanic eruptions or 
floods that carry away the 
soil can lead to primary 
succession.

37. *Any species to move into a devastated area is a pioneer species.
*They must be able to live on limited resources.
*Examples include bacteria and tiny plants.
*Lichens are common pioneer species because they can live on bare 
rocks.
*The formation of soil is the first step in primary succession.
Primary Succession Animation

38. SECONDARY SUCCESSION:
*Secondary succession occurs when a disturbance changes or partially destroys an 
ecosystem, but leaves the soil.
*Examples: abandoning farmland, leaving a logged forest to regrow, or burning down a 
forest
Secondary succession

39. Succession Eventually Slows:
*Succession does not continue indefinitely. 
*A more stable community called a climax community eventually forms.
*A climax community has organisms that 
are well adapted to the environmental 
conditions and can survive and reproduce.
*Examples include the swamps of Florida 
and the old growth forests of the Pacific 
Northwest.
*Climax communities can restart due to 
natural disasters or human impact.

40. Populations:
*A population is a group of organisms of one species that live in the 
same place at the same time.
Organisms in a population compete for  
 -food
 -water
 -mates

42. Population Density: is the number of individuals that live in a defined 
area.

44. Factors that affect the size of a population:
Immigration-movement of individuals into a population.
Births
Emigration-movement of individuals out of a population
Death

45. Types of Population Growth:
Exponential Growth:
J-curve graph:
A population grows rapidly because of an abundance of resources.
Birth rate exceeds death rate

46. Logistic Growth:
A population begins with a period of slow growth followed by a brief period of 
exponential growth before leveling off at a stable size.
The carrying capacity is the point at which the population growth becomes stable. 
(max. number of indiviudals an environment can support)
S-curve:

47. ecological factors limit pop. growth.
Limiting Factors:
ecological factors limit pop. growth.
Density-Dependent 
Limiting Factors:
Competitition
Predation
Parasitism/Disease
(affected by the number of organisms that live in a given area)

48. Unusual weather (droughts, floods) Natural disasters Human activities
Density-Independent 
Limiting Factors
Unusual weather (droughts, floods)
Natural disasters
Human activities
(affect the populations regardless of their size)

50. Attachments
Biologically_Speaking__Ecosystems_and_the_Cycles_of_Nature.asf
Symbiosis.asf