3.1 – What is Ecology?
Interactions and Interdependence
• Ecology – the study of interactions among organisms and
their environment
• Oikos (ec) – Greek word meaning house
• Ology – means study of
Levels of Organization
•
The levels of organization that ecologists study include:
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Individuals
•
Species – group of similar organisms that can breed
and produce fertile offspring
•
Populations – group of individuals of the same
species that live in the same area and interbreed
•
Communities – different populations that live together
in a defined area
•
Ecosystem – The interaction of all the organisms and
the environment in a given area
•
Biome – a group of ecosystems that have the same
climate
•
Biosphere – part of Earth in which life exists including
land, water and atmosphere
•
It extends about 8km above the Earth’s surface to
about 11km below
•
If you could shrink earth to the size of an apple, the
biosphere would be thinner than the apple’s peel
Biotic and Abiotic Factors
•
Biotic Factors – all the living organisms in an ecosystem
•
•
Abiotic Factors – nonliving factors in an ecosystems
•
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Example: temperature, precipitation, wind, soil, sunlight,
humidity
Habitat – area where an organism lives
•
•
Example: tree, bird, bacteria, fungi
Includes both biotic and abiotic factors
Niche – the role and position a species has in its
environment
•
No two species can share the same niche in the same
habitat
3.2 – Energy Flow
•
Sunlight is the main energy source for life
•
Autotrophs
•
Make their own energy
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Convert sun energy into chemical energy
•
Also called a producer
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Plants are the main autotrophs on land
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Algae are the main autotrophs in water
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Some autotrophs can produce food in the absence of light
•
Chemoautotrophs – organisms use chemical energy to
produce carbohydrates
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Performed by several types of bacteria
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Live in…
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Volcanic vents
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Deep ocean
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Hot springs
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Marshes
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Heterotrophs
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Get energy from other organisms
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Unable to make its own energy
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Also called consumers
•
Types of Heterotrophs
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Herbivores
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Eats only plants
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Example: cows, deer, rabbits, bees,
elephants, squirrels
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Carnivores
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Eats only animals
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Example: snakes, dogs, lions, crocodiles
Omnivores
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Eats plants and animals
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Example: humans, bears, crows
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Detrivores
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Eat decomposing bits of organic matter
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Example: mites, earthworms, snails, crabs
Decomposers
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Break down organic matter
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Example: bacteria and fungi
Scavenger
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Ingest nonliving plants and animals
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Example: vulture, termite, beetle
Feeding Relationships
•
Food Chain – a straight line series of steps by which
energy is stored and passed on to higher trophic levels
•
Food Web – a network of crossing interlinked food chains
that shows all the possible feeding relationships at each
trophic level
•
Energy is passed through no more than four or five trophic
levels
•
Trophic Levels – step in a food chain or food wed
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Plants and other producers are 1st trophic level
•
Consumers make up the 2nd, 3rd, or higher trophic
levels
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Each consumer depends on the trophic level below it
for energy
•
Energy is transferred from one trophic level to another
and is never 100%
•
At each trophic level only 10% of the energy taken in
by the organism is stored. The rest is used up during
metabolism to process the energy
Ecological Pyramids
•
Ecological Pyramid – a diagram that shows the relative
amounts of energy or matter contained within each
trophic level in a food chain or food web
•
Example: Ecological Pyramids
Community Interactions
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Competition – occurs when organisms of the same or
different species attempt to use the same resources
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Predator – eat other animals
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Prey – the animal a predator eats
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Symbiosis – relationship in which two species live closely
together
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Three Types of Symbiosis
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Mutualism
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Both species benefit from the relationship
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Example: plants and bacteria on roots
Shark and fish
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Commensalism
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One organism benefits and the other is neither
helped nor harmed
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Example: tree and bird nest
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Parasitism
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One organism lives on or inside another organism
and harms it
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Example: tick, ringworm
Fig. 48.12, p. 862
3-3 Cycles of Matter
•
Biogeochemical Cycles – process in which elements,
chemical, and other forms of matter are passed from one
organism to another and from one part of the biosphere
to another
The Water Cycle
•
Evaporation – process by which water changes from a
liquid to a gas
•
Transpiration – loss of water from plants by the process
of evaporation
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Condensation – water vapor changes to a liquid
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Precipitation – water returns to the earth (rain, snow,
hail)
The Carbon Cycle
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Carbon is released into the atmosphere by…
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Respiration
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Burning fossil fuels
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Volcanic activity
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Burning trees
Carbon is taken out of the atmosphere by…
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Carbon is released into the ground by…
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Photosynthesis performed by plants
Decomposition
Carbon is taken out of the ground by…
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Mining oil and coal
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Roots of plants
CO2
Volcanic
Burning
Activity Fossil Fuels
Burning
Trees
Photosynthesis
Respiration
Organism eats plants
C6H12O6
Decomposition
Oil
Coal
Root Uptake
Nitrogen Cycle
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Gaseous nitrogen (N2)makes up 80% of the atmosphere
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Nitrogen Fixation
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Bacteria convert N2 to ammonia (NH3)
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This dissolves forming ammonium (NH4)
Ammonification
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Bacteria degrade nitrogenous wastes and remains
of organisms.
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Convert NH3 to NH4
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Nitrification
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Bacteria convert NH4 to nitrite (NO2) to nitrate (NO3)
Denitrification
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Bacteria convert extra nitrates or nitrites (NO3, NO2) to
N2
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N2 is released back into the atmosphere
Gaseous Nitrogen
N2
Nitrogen Fixation
Ammonification
Denitrification
Bacteria in the soil convert
Bacteria convert wastes and
decomposing organics to
Bacteria convert
N2 → NH3 → NH4
NO3 → N2
NH3 → NH4
Autotrophs can take up
NH4 and NO3
Nitrification
Bacteria convert
NH4 → NO2 → NO3
•
Humans are harming the nitrogen cycle by:
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Deforestation
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Conversion of grasslands for agriculture
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Sewage enters waterways
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Fossil fuel burning
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Vehicles having combustion engines releases NO2
4-2 What Shapes an Ecosystem?
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Ecological Succession
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Succession – changes that occurs in a community over
time
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Pioneer Species – first species to populate the area
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Climax Community – a stable mature community that
undergoes little or no change in species
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Two Types of Succession
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1. Primary Succession
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Succession that occurs on surfaces where no
soil exists
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Example: rock surfaces formed after volcanoes
erupt
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Secondary Succession
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Succession following a disturbance that destroys a
community without destroying the soil
•
Because soil already exists, secondary succession
usually takes less time than primary succession
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Example: fires, floods, farming, construction,
hurricanes, tornadoes