What is Ecology?
Ecology
 Study of interactions among
1. Organisms
2. Organisms and their environment
 Species- a group of similar organisms that can breed and
produce fertile offspring
 Biotic factors- biological (living) influences on ecosystem
o Ex. Interactions between organisms, predation,
symbiosis, etc.
 Abiotic factors- nonliving influences on ecosystems
o Ex. Temperature, precipitation, nutrient availability,
soil type, sunlight.
Habitat vs. Niche
 Habitat- an area where an organism lives
 Niche- an organism’s role in its environment-how it obtains
food & shelter, finds a mate, cares for its young, and avoids
danger.
 Habitat is like an address in an ecosystem and a niche is like
an occupation in an ecosystem.
Ecological Levels of Organization
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Individual- one living thing (organism)
Example: a moose
Population- groups of individuals that belong to the same species
and live in the same area.
Example: many moose
o Species- a group of similar organisms that can breed and
produce fertile offspring.
Community- groups of different populations (more than one
population or different groups of species)
Example: many groups of moose, beavers, trees, grass (all living)
Biome- group of ecosystems that have the same climate and
similar dominant communities
Example: tropical rain forest, savanna, desert, temperate forest,
taiga, tundra, etc.
Biosphere- all of the planet where life exists,
includes land, water, and air
Life extends 8 km up and 11 km below the
surface
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Living Things Need Energy
 Organisms in any community can be separated into three groups based on
how they get energy: producers, consumers, and decomposers.
Producers
 Producers- make their own food by capturing energy from sunlight
(photosynthesis) or chemicals (chemosynthesis) and using the energy to
produce food.
 Producers are autotrophs-they make food from their environment
 Usually plants but can also be bacteria & algae
Consumers
 Consumers- get energy from consuming other organisms
 Consumers are heterotrophs- get energy by eating other organisms
 4 types of consumers
 Herbivores- eat only plants (cows, deer)
 Carnivores- eat only animals (lions, wolves)
 Omnivores- eat both plants and animals (bears & raccoons)
 Scavengers- eat dead matter-plants and animals (vultures, worms,
insects, crabs)
Decomposers
 Decomposers-recycle nature’s resources.
 They get energy by breaking down dead organisms into simple materials
& recycle the materials back into the environment.
 These materials, such as carbon dioxide (CO2), water (H2O) & nitrogen (N2)
can be used by other organisms.
 Examples include bacteria and fungi
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Feeding Relationships
 Energy flows through an ecosystem in one direction from:
1. The sun or inorganic compounds
2. To autotrophs (producers)
3. To heterotrophs (consumers)
4. Decomposers get energy from decomposing dead organisms
Energy Pyramid
 An energy pyramid shows how energy moves in an ecosystem.
 Only part of the energy stored in one level can be passed to the nextmost energy is consumed for life processes (respiration, movement, etc.)
and given off as heat.
 Only 10% of the energy available within one trophic level is transferred to
organisms in the next trophic level
4th trophic level
3rd trophic level
2nd trophic level
1st trophic level
 Food Chain- the path energy takes from one organism to another.
Producers form the beginning of all food chains.
In a food chain:
• Producers are eaten by primary consumers
• Primary consumers are eaten by secondary consumers
• Secondary consumers are eaten by tertiary consumers
 Food Web- a system of many connected food chains in an ecosystem.
Organisms in different food chains may feed upon one another. (More
realistic than a food chain)
Biomass Pyramid
 Biomass – the total amount of living tissue within a given trophic level
 A biomass pyramid represents the amount of potential food available
for each trophic level in an ecosystem.
Trophic levels
 Each step in a food chain or a food web is called a trophic level.
 Producers are the first trophic level
 Consumers are the second, third, or higher trophic level
 Each trophic level depends on the one below for energy
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Phosphorus Cycle
 Movement of phosphorus through the air, water and land.
 Importance of Phosphorus
 Important nutrient for plants and animals
 Part of DNA molecule in our cells
 In the fats of our cell membrane
 Part of our bones and teeth.
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Nitrogen Cycle
 Circulation of nitrogen; nitrates from the soil, absorbed by
plants, eaten by animals that die and decay returning the
nitrogen back to the soil.
 Plants absorb nitrogen from the soil.
 Animals get nitrogen from eating plants.
 Animals and plants release nitrogen in waste.
 Bacteria break down nitrogen and release it back into the air
(denitrification)
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Types of Interactions
I. Adaptations
A. An adaptation is any physical or behavioral characteristic that
helps an organism survive in an environment
B. Adaptations are suited to specific living conditions – polar
bears fur would not work in the tropics, and a fish’s fins would
not work on land
C. Adaptations have evolved over thousands and millions of
years to allow organisms to live successfully – those that
cannot adapt do not survive (go extinct)
D. The particular role an organism has in an environment is
known as its niche – what it eats, how it gets food, what other
organisms it interacts with in that environment.
II. Types of interactions between organisms
A. Competition occurs due to a limited number of resources
 Resource- any necessity of life: water, nutrients, light,
food.
 Competitive exclusion principle- no two species can
occupy the same niche in the same habitat at the same
time – Why?
One organism would compete better and the other will die
out (extinct).
 Adaptations may include methods or features that aid in
competition –physical ones such as horns or chemical
deterrents or behavioral adaptations such as time of day
for feeding
B. Predation – interaction between predator and their prey.
 Predator adaptations such as speed, claws, hunting in
packs
 Prey adaptations such as:
o Protective covering – spikes on sea urchin or porcupine
o Mimicry – pretends to be something else –moth with
eyespots looks like a bird, caterpillar that looks like a
snake, milk snake looks like coral snake, etc.
o Camouflage – blending in to the environment
o Warning coloration – bright colors typically mean poison
(or pretending to be poison)
C. Symbiosis- any relationship where two species live closely
together. (3 types)
o Mutualism
o Commensalism
o Parasitism
 Mutualism- both species benefit from a relationship.
Ex: Lichens (fungus and Algae)  
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 Commensalism – One member of a symbiotic relationship
benefits and the other is neither helped nor harmed.  
Ex: Clownfish uses a sea anemone as shelter which does not
harm the sea anemone
 Parasitism- One creature benefits and one creature is harmed

Ex: tapeworm feeds in a human’s intestines absorbing his/her
nutrients to the person’s detriment.
ECOLOGY—Cycles of Matter
How matter is recycled through the environment
 Matter is limited, so it must be recycled.
 Matter moves between the environment (abiotic) and living
things (biotic).
 Each type of matter has its own cycle.
 4 important cycles
 Water Cycle
 Carbon Cycle
 Nitrogen Cycle
 Phosphorus Cycle
Water (Hydrologic) Cycle
 the continuous movement of water on, above, and below the
surface of the Earth.
 Evaporation – change of water from liquid state to gas state
 Condensation – water vapor (gas) turning into a liquid
 Transpiration – water released by plants into the air
 Surface run-off – soil is full and excess water travels over land
 Percolation – Movement of water through the soil
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Carbon Cycle
 The circulation of carbon from the atmosphere into
organisms; travels through organisms, and back to the nonliving world; goes through the air, land and water.
 Photosynthesis – plants make sugar from sunlight. Light
energy is turned into chemical energy (sugar).
 Plants use carbon dioxide and produce oxygen
(photosynthesis) / Animals use oxygen and produce carbon
dioxide (respiration)
 People add carbon to the air by burning fossils fuels.
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