Principles of Ecology Unit 5

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

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)

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

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

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

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

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

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

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

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

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.

ENERGY IN ECOSYSTEMS

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

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

-Example of cyanobacteria

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

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

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

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

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.

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

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. 5 500.000 5000

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

*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

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

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

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

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

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

Commensalism One species 
benefits and 
the other is 
not affected.

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.

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. . -

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.

*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

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

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.

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

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

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

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

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:

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)

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)

Attachments Biologically_Speaking__Ecosystems_and_the_Cycles_of_Nature.asf Symbiosis.asf