ECOLOGY I
1/17-1/27
What is Ecology?
• The study of the interactions
of living organisms with one
another and with their
environment.
1. Biotic & Abiotic factors
• Biotic – all of the living
organisms that inhabit an
environment
• Abiotic – all of the nonliving
parts of the environment
such as, air currents, temp.,
moisture, light , minerals in
soil, topography, etc.
2. Levels of Organization
• Organism – an individual living
thing. Ecologist would study
daily movement, size, etc.
Population
• interbreeding individuals of one
species that compete for food,
water, and mates
• live in the same place at the
same time
• An ecologist would study
population growth territoriality,
intra-specific competition, etc.
Community
• several interacting populations
that inhabit a common
environment
• able to function b/c each organism
w/in the ecosystem depends on
other organisms
• An ecologist would study food
chain and webs, parasitism, etc.
Ecosystem
• populations in a community
and abiotic factors w/which
they interact
• ex: terrestrial and marine
ecosystems
• An ecologist would study the
effects of light, moisture, temp.
etc. on organisms and all of the
interactions of those orgs.
w/each other.
Biosphere
• the area of the earth
where all life exists
• An ecologist would study
how global matters affect
orgs. such as, El Nino,
greenhouse effect, ozone
depletion, etc.
3. Compare Niche and Habitat
• Niche – role a species plays in
a community such as feeding
relationships and space
• what the org. needs to survive
in the environment
• includes how a species uses
and affects its environment.
• Habitat – the place where an
org. lives out its life.
• Different species of orgs.
may appear to have the same
habitat, but each has a
different niche so that they
can survive in that habitat.
4. & 5. Organism Interaction
• Autotrophs – Organisms that
use E from the sun or E stored
in chemical compounds to
manufacture their own food.
Ex: green plants AKA
producers; all other orgs. in
community depend on
producer
• Heterotrophs – org. that depend on
other organisms for their source of
food and E. AKA consumers.
–Herbivores – feed on plants
–Carnivores – kill and feed on other
animals
–Scavengers – feed on org. they did
not kill
– Omnivores – eats plant or animals
• Predator/Prey Relationship
–Predator does the hunting
–Prey is the hunted
–Decomposer – break down
and absorb nutrients from
dead org. or waste products
from org.
• Bacteria, some protozoans
and most fungi
• Dead org. is recycled back
into ecosystem
• Detritivors – organisms that
obtain their E from the
organic wastes and dead
bodies that are produced at
all trophic levels.
6. Energy Relationships
• Food chain – shows simple
relationship of what organism
consumes what organism.
–Rarely exists in nature since it
represents only one way that E
can be transferred in an
ecosystem
• 2 Rules to follow when making
a food chain
–Always start with a producer
organism
–Arrow always goes in the
direction of E flow
Grass Grasshopper Shrew
Organisms Grass Grasshopper Shrew Rat
Snake
Trophic 1st 2nd 3rd 4th
Level
Producer 1st Consumer 2nd 3rd Con.
Con.
Autotroph Heterotroph Hetero Hetero
Producer Herbivore 1st 2nd
Carniv Carnivore
10% Rule 10,000 C 1,000 C 100 C 10 C
10% Rule
• As E is transferred from one
trophic level to the next, 90% is
lost as heat to the environment
and only 10% is transferred as
tissue in the next trophic level
for the next level to use. (This
is a rough rule of thumb to
show what happens to E in a
food chain. )
• Food Web – tries to explain
all of the feeding
relationships at each trophic
level in a community. A food
web is more realistic than a
food chain since most orgs.
feed on more than one org.
Cooper’s Hawk
Loggerhead Shrike American Kestrel
Shrew
Grasshopper Cricket Deer Mouse Sparrow
Grass & Seeds
• Ecological Pyramid – shows
relationships in food chains
and food webs. The bottom of
the food pyramid represents
the producers, the next level
the herbivores, the next the 1st
carnivore, and the next and/or
top carnivore. The shape of
the pyramid indicates that it is
largest on the bottom and gets
smaller toward the top.
• Pyramid of Energy – shows
energy relationships
between trophic levels in the
form of calories.
• Pyramid of Numbers –
Shows number relationship
between numbers of org. at
different trophic levels.
• Pyramid of Biomass – shows
the dry weight of tissue and
other organic matter found in
a specific ecosystem.
7. Cycles
• The kinds and amounts of
elements on Earth are
relatively constant. Nothing
added or subtracted. All
elements are recycled
Nitrogen Cycle
• Largest part of nitrogen is in
the atmosphere – 78%.
• Worksheet explains.
Carbon Cycle
• Most of C is located in the
atmosphere in the form of
carbon dioxide.
Photosynthesis is involved.
• Worksheet
Water Cycle
• The amount of water on the earth is
constant. Most is found in the
ocean – 97%. 3% is fresh water. Of
that 3%, 76% is located in icecaps
and glaciers, 23% is ground water
and 1% other water – lakes, rivers
soil moisture, & in atmosphere
8. Nutrient Cycles &
Homeostasis
• Nature does not throw anything
away
• E flows from the sun to
producers then to consumers
• Carbon atoms, nitrogen & water
are recycled
Kingdoms and E Relationships &
Cycling of Nutrients in Environ.
• Kingdom Eubacteria – true
bacteria
–Decomposers
–Nitrogen cycle
• Relationship with legumes
• Protista – plant-like protists like
algae are autotrophs & produce
carbohydrates through PSN
–Produce more oxygen than all
other autotrophs put together
–Animal-like protists like
paramecium and amoeba are
heterotrophs at bottom of food
chain
• Fungi all are heterotrophs,
most decomposers
–Involved in breaking down
dead plant matter
–Mushrooms and bracket
fungi are examples
9. Stages of Succession
• Succession – orderly, natural
changes that take place in the
community of an ecosystem
• Primary succession – changes
that occur on soil that has
never supported plant life
• Succession eventually ends up
in what is called a climax
community
–Climax community – stable,
mature community that
undergoes little or no
succession – the new trees
(plants) that are coming up
under the old trees are the
same species as the old trees.
• Secondary succession –
changes that occur on soil
that has supported plant life.
–Plant growth after a fire,
flood, volcanic eruption or
any natural or man-made
disaster
10. Compare/contrast organisms
relationships
Predator/Prey Relationship
Predator does the hunting
Prey is the hunted
–Competition – the
relationship between species
that attempt to use the same
limited resources
• Symbiosis – a relationship
where there is a close and
permanent relationship
between organisms of
different species
–Commensalism – a
relationship where one
species is benefited and the
other is neither harmed nor
benefited. Ex – bird’s nest in
a tree
–Mutualism – relationship
where both species benefit.
Ex – ant and acacia tree
–Parasitism – a relationship
where one organism is
harmed (but not usually
killed) and the other org. is
benefited. Ex – flea on dog