Transcript Notes for Ecology unit - Liberty Union High School District

1. All organisms are made of cells

Cells are the smallest unit of life
2. All organisms need energy


Any living organism needs energy to
live
They take in and use energy.
3. All organisms respond to the
environment

What happens to an organism
depends on the environment they are
living in.
4. All organisms reproduce


Living organisms can
make more of
themselves
Two types:
– asexual
– sexual.
5. All organisms grow and develop

Get bigger as they get older.
6. All organisms carry DNA


Carry their own genetic code
Traits are passed to offspring
7. Internal Balance (Homeostasis)

Living things maintain stable internal
conditions

Examples
– Temperature
– Water Balance
– Heart Beat
Key Knowledge:
1. Matter Cycles, Energy Flows
2. Abiotic factors cause changes in Biotic factors in a
ecosystem
Abiotic: Non-living parts of the
environment
Soil
 Sunlight
 Climate
 Temperature
 Rainfall
 Nutrients

Biotic: Living parts of the
environment

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
Plant
Animals
Decomposers
(Bacteria and Fungus)
General Organization
Organism= any individual living
thing
 Population= Individual
organisms of a single species
in one area.
 Community= more than one
population living in the same
area.

Different
species of
fish
Different
species of
corals
(animals)
Starfish
(animal)
Example of a
Community
Algae
(microscopic plants)
General Organization
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Ecosystem= All the populations and
abiotic factors in an area.
Habitat = the environment that a
particular species prefers within an
ecosystem
Niche= the role that an organism fills
“job”
Biomes= Ecosystems with similar
characteristics.
Characteristics of a Biome
No distinct boundaries
 Defined by types of plants
 Similar climate conditions, but may be
located in a totally different part of the
world ( Africa and Asia)
–land biomes
–water biomes (marine or freshwater)

List the ecosystem
structure from small to
large..
Can make their own food through
energy from the sun or inorganic
substances
AKA: Primary Producer
Obtains energy by eating other
organisms,
AKA: Consumers
Types of Consumers
Primary consumers: eat producers
(herbivores)
Secondary consumers: eats both
producers & consumers (omnivores)
Tertiary consumers: top predator
(carnivore)
Trophic levels are a way of identifying
what kinds of food an organism
uses.
1st trophic level= primary producers
2nd trophic level= primary consumers
3rd trophic level= secondary consumers
4th trophic level= tertiary consumer
Decomposers & Scavengers

Decomposers feed on wastes & dead
material from all trophic levels


Ex: bacteria, fungi
Scavengers are consumers that eat
dead animals (like road kill)

Ex: vulture
Energy in an ecosystem
is transferred (cycles)
through the trophic
levels of that ecosystem
Biomass and Energy Transfer
1 hawk
10 snakes
100 mice feed
1000 plants feed
****Rule of 10****
Only 10%
of the energy is
transferred
to the next organism
Very few animals feed on only one food
source, Food Webs are a more accurate
picture of how animals feed.
Biological Magnification
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The build-up of toxins in living organisms
with movement up the trophic levels .
Toxins collect in at the top of food web
because top consumers eat so much.
Examples:
DDT: Dichloro Diphenyl Trichloroethane
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Developed during WWII as a
pesticide
Very high levels of DDT were
found in top consumers.
 DDT is stored in fat.
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Organisms died or had
reproductive problems
Banned in US and Canada during
the 70’s.
Still found in almost all living things

Developing countries are still use DDT
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Community Interactions
In order to sustain an
environment, organisms and
abiotic factors interact
EXAMPLES:
–Symbiosis
–Succession
Forms of Species Interaction
Symbiosis:
relationships between two
species (3 types)
1. Parasitism: one organism benefits at
another’s expense ( Humans and tape worm)
2. Commensalism: one organism
benefits while the other is unaffected
(anemone and clown fish)
3. Mutualism: both organisms benefit
from the interaction (rhino and bird)
Forms of Species Interaction Continued
Competition: two species are fighting
for the same resources
Predation: one species hunts the
other
Ecological succession: change in the
types of species in a community
observed over time
Why does succession
happen?
Communities & environments
change over time
1) Primary Succession
When communities form in new areas
– Ex: volcanoes, rocks, etc
Steps of Primary Succession
1.
Pioneer species appear  lichens
(grow on rock & turn it into soil)
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2.
3.
4.
5.
Pioneer Species: the first organisms
occupy an area
to
Grass & small plants appear
Weeds & shrubs
Shallow trees (ex: pine trees)
Climax community  stable & final
stage (ex: deciduous trees)
Climax Community
A community that
has achieved
stability and
species diversity
2) Secondary Succession

Occurs in areas that were cleared by
disturbance (fire, etc)
– faster than primary (soil already formed)

Same as primary except pioneer
species are grasses instead of lichens
Succession
leads to…..
FACTORS THAT AFFECT
POPULATION GROWTH
1.Birth Rate
2.Death Rate
3.Immigration (movement into an area)
4.Emigration (Movement, exiting an area)
Exponential Growth
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J-shaped curve on a graph
Population doubles every generation
Humans are reproducing this way!
Humans - Trouble ahead?
Logistic Growth
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S–shaped curve on graph
How real growth looks
Populations grow fast early, then slow
down, as we get closer to CARRYING
CAPACITY
Biomass
and
Energy Transfer
at the lowest
Trophic level
determines the
Carrying Capacity of
the ecosystem.
Carrying Capacity
Maximum # of individuals a population
can support
– Populations will increase to Carrying
Capacity, and they decrease again once
they have reached it.
Limits to Pop. Growth
1. Density-dependent limiting factors
– Affect crowded populations
– Disease
– Competition (for shelter, food, water)
– Predation (predator eats prey)
How might the
Bubonic
Plague have
been different
if the Medieval
populations
didn’t live so
close to each
other?
2. Density-independent limiting factors
– Affect all populations (crowded or not)
– Weather
– Natural Disasters (fire, etc)
– Human activities
New Orleans, LA
Gulf Port , MS
Would the
physical
effects of
Hurricane
Katrina be
any different
in a Town of
100, then in a
town of
100,000?
All matter essential for life moves in
cycles between living things & the
environment
Examples of cycles:
carbon cycle
water cycle
nitrogen cycle
What is Carbon
The basic building block of
organic compounds essential
for life.
Why is carbon important to us?
1) Carbon is used to make hair,
muscle, & skin
2) Carbon stores energy so living
things can think, move, etc
3) Fossil fuels (gas, coal, oil) are
made from carbon
Where is carbon found in the environment?
1.
2.
3.
atmospheric gas (CO2)
rocks (limestone, diamonds)
fossil fuels (oil, coal, etc.)
How does carbon enter living things?
1) CO2 gas enters plants
2) Photosynthesis allows plants to
change CO2 into a sugar
3) Animals then get carbon by eating
the sugar found in plants
How does carbon get back
into the environment?
1. Plants & animals release CO2 during
respiration
2. Burning of wood & fossil fuels
3. Using electricity, (most power plants use
fossil fuels)
4. Cow farts (seriously)
5. Decomposition when bacteria and fungus
break down tissue of dead things
How are fossil fuels formed?
1.
2.
When living things die & fall to
the bottom of water, they are
buried & compressed
They eventually form coal,
petroleum, or natural gas
So what’s the cycle?
the 2 main steps are
photosynthesis & respiration!
The Carbon Cycle
The movement of carbon through the
environment
2 major driving forces
1. Photosynthesis- plants and algae take up
CO2 from the air or water to make sugar
2. Cellular Respiration- consumers use
sugar for energy and release CO2 into the
air or water
Future Predictions
Due to humans using more fossil
fuels, more CO2 is released each
year
this may result in global warming since
CO2 traps heat (remember the
greenhouse effect)
What is global warming?
Facts about Nitrogen
78% of air is nitrogen gas (N2)
Living things can’t use nitrogen
when it’s a gas (N2)
Why do living things need
Nitrogen?
 To
make amino acids & proteins
 To make DNA
The Nitrogen Cycle
Step #1
Nitrogen gas (N2) is found in the
atmosphere
Step #2
”Nitrogen Fixation”: Bacteria
living at the roots change
the N2 gas into a usable
form like ammonia or
nitrates

Lightning also “fixes” nitrogen
Step #3
Plants then use the ammonia
or nitrates in the soil
Step #4
Animals get nitrogen from
plants by eating them
Step #5
When plants & animals die, the nitrogen
in them is released back into the
atmosphere as a gas (N2)

This is done by denitrifying bacteria
Step #6
Nitrogen gas is released back into the
atmosphere
What are the two process
that are responsible; for
cycling Carbon in the
environment?
What things add carbon?
Which things take it away?
Photosynthesis and Cellular Respiration
Photosynthesis : take it away
Cellular Respiration, Fossil Fuels and
Decaying organisms add it.
Breaking the Water Cycle
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The only way for water to get back
to the atmosphere is through
transpiration (plant sweating)
When we cut down trees they no
longer transpire
So water does not get into the air
to become rain
The area becomes a desert in a
very short time period
– Really bad in rainforest regions,
because the soil is so shallow
HUMAN IMPACT
A Sad True Story
Invasive Species
A species that is brought by HUMANS into
a new environment and outcompetes the
ones already there.
Example: Africanized Honey Bees, which
will take over the hive of the honey bees.
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An Ecological Mystery
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Long term study of sea otter population along
the Alaskan and Aleutian Islands
1970: Sea Otters healthy and populations
growing
1990: Sea Otter #’s declining
– Maybe due to emigration, not deaths

1993: 800 km area in Aleutian Islands studied
– Sea Otter #’s reduced by 50%
Vanishing Sea Otters
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1997: Study of area repeated
Sea Otter pop. had declined by 90%
– 1970: > 53,000 Otters in the study area
– 1997: < 6000
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Why?
– Reproductive issues
– Starvation, Pollution, Disease?
Cause of the Decline
 1991: one researcher observed an Orca
whale eating a sea otter.
 Sea lions or seals are the normal prey of
Orcas.
 Decline in usual prey led to feeding shift.
 Single Orca could consume 1,825
otters/year.
 Clam Lagoon (CONTROL GROUP), which
was not accessible to Orcas, had no
decline in otter population
No Big Deal.. Right?
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Declines in ocean fish due to over fishing
and climatic changes led to a reduction in
food for sea lions & seals, so their #’s
decreased
This forced the orcas to enter into the
coastal waters where they consumed sea
otters.
Sea otters normally feed on sea urchins.
As sea otters decreased, the urchins
numbers increased.
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Urchins eat kelp, and the large numbers of
urchins damaged kelp forests.
The decline in the kelp forests has had an
impact on many others species because of
the decrease of oxygen and an increase in
carbon dioxide in the water.
Other Species Affected
Bald Eagle
Mussel
Sea Stars
Seagulls