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Ecology Need-to-Know
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Ecology is the study of the interactions of organisms with one another and
with their physical environment.
Biosphere - part of the Earth in which life exists.
Ecosystem - consists of an area’s physical features and living organisms.
 System- a set of interacting or interdependent components that
form an integrated whole
o Abiotic factors - physical features
 Ex. elevation, humidity, rainfall
 (SWATS: soil, water, air, temp, sunlight)
o Biotic factors - living organisms
 Ex. snails, worms, plants, insects
Community - all the populations of organisms living in a given area.
o Ecosystems rarely function independently of one another because they
are connected by both living and non-living features.
Ecological succession - an existing community of organisms is replaced by a
different community over time.
o Can occur where no living community existed before (like a volcano
arising from the sea).
o Can also occur following a dramatic change (like a forest fire).
o Succession leads to a collection of organisms called a climax
community.
Biomes –see
“Biomes Outlines Lab” for specifics of each Biome
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Biome - an environment that has a characteristic climax community.
o Terrestrial- associated with a land environment
 Tropical
 Tropical Rain Forest
 Grassland
 Tropical Grassland
 Temperate Grassland
 Desert
 Temperate
 Temperate Deciduous Forest
 Temperate Rain Forest
 Taiga
 Tundra
o Aquatic- associated with a water environment
 Freshwater- (rivers, streams, ponds, lakes, wetlands)
 Estuaries
 Marine (intertidal zone, coastal ocean, open ocean)
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Habitat- an area that provides an organisms with its basic needs for survival
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Endemic species- a species found in its originating location and is generally
restricted to that geographic area
Non-native species – species introduced into an area outside of their rang by
accidental or deliberate human activity
-can also be called: introduced, invasive, alien, nonindigenous, or exotic
Energy Flow in Ecosystems
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Of all the sun’s energy the reaches the Earth’s surface, only about 0.1% is
used by living things.
Energy cannot be recycled or used again!
For this reason, we refer to the movement of energy through an ecosystem as a
flow, not a cycle.
Biochemical conversion- the changing of organic matter into other chemical
forms such as fuels
Bioenergetics- the study of energy flow (energy transformations) into and
within a living system
The sun is the ultimate source of energy for living things.
Producers - organisms that make their own food via photosynthesis.
Consumers - organisms that get their energy directly or indirectly from
producers.
o Primary consumers - also called herbivores; plant eating animals.
o Secondary consumers - animals that eat primary consumers.
Trophic level - each step in a series of organisms eating other organisms.
o At each higher trophic level, less and less of the energy originally
captured by the producers is available.
o Only about 10% of the energy from one trophic level can be used by the
animals at the next trophic level!
Herbivores - organisms that eat only plants.
Carnivores - organisms that eat only animals.
Omnivores - organisms that eat plants and animals.
Decomposers - organisms that obtain energy from non-living organic matter
Ecosystem Relationships
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Food chain - simplest feeding relationship linking animals and plants in the
biosphere.
o Usually contains 3-5 total organisms.
Food web - complex relationship formed by interconnecting and overlapping
food chains.
o Competition- finite amount of resources to compete over
o Predation- one species uses another as food
o Symbiosis-a close and usually obligatory association of two organisms
of different species that live together, often to their mutual benefit
 Commensalism –one organism benefits without affecting the other
 Parasitism –one organism benefits (the parasite), at the expense
of the other (host)
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Mutualism – each organism benefits
Nutrients are Recycle Through Ecosystems
– see
“Biogeochemical Cycles Lab” for examples of each cycle
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nutrients are recycled and used again and again.
Biogeochemical cycle - nutrients use these processes to move through the
biosphere.
o Ex. Water, carbon, nitrogen, oxygen cycles
Water cycle - movement of water between the atmosphere and Earth.
o Consists of alternating cycles of evaporation and condensation.
Carbon Cycle- movement of Carbon through the biosphere
o Carbon- required for all organic compounds
Oxygen Cycle- movement of Oxygen through the biosphere
Nitrogen cycle - movement of nitrogen through biosphere.
o Most can’t be used directly by living organisms - it must be converted
into more usable forms.
o Nitrogen - element required by living organisms to build proteins.
Limiting factor - the nutrient that is in short supply that limits an
organism’s growth.