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ECOLOGY
The Study of Interactions between
Organisms and their Environment
Ecology Vocabulary
• Population: a particular species in an area
• Community: a group of populations in an area
• Ecosystem: a community plus its non-living (abiotic)
environment
• Biosphere: all regions of the planet inhabited by
populations
• Habitat: The place a population lives
• Niche: the role of the population in the environment
(what you eat, what you do)
ECOSYSTEM FACTORS
• BIOTIC: Living
– AUTOTROPHS (producers)ex. plants
– HETEROTROPHS (consumers)ex. Animals
an omnivore ,a carnivore and a herbivore are
all heterotrophs
– DECOMPOSERS ex. Bacteria, fungi
• ABIOTIC:Non-living
temperature, sunlight, water, minerals
Trophic Levels
Trophic Levels
• Primary Producers: The autotrophs that
capture energy to make food (Plants)
• Primary Consumers: heterotrophs that eat
autotrophs (herbivores)
• Secondary Consumers: heterotrophs that eat
other heterotrophs (carnivores)
• Higher Level Consumers: carnivores that eat
other carnivores
• Decomposers: consumers of dead organic
material ( Bacteria, Fungi)
ENERGY FLOW
• Food chains: a specific energy pathway
• Food webs: complex energy interactions in
found in an ecosystem.
Energy pyramids: representation of the total
energy available to a trophic level.
FOREST FOOD WEB
Arctic Marine Food Web
Biomass Pyramid
Energy Pyramid
Kruger Park Battle
Growth of Populations
• Exponential Growth : the maximum
possible growth rate of a population
• Carrying Capacity of the Environment:
The maximum population that a
particular environment can support
• Limiting Factors : those environmental
factors that keep a population at the
carrying capacity, like food, predators,
amount of water, how much land there is
Population Growth over Time
In 1944, 20 reindeer were brought to
St. Matthew Island. Initially there were abundant food
sources, and the reindeer population increased dramatically.
There were no predators to cull the population.
However, about 20 years later, the reindeer had overshot
the food carrying capacity of the island, and there was a
sudden, massive die-off. About 99% of the reindeer died
of starvation.
Exponential
growth can
lead to
massive die-off
Carrying capacity
of the
Environment
Community Interaction
• competition
Predator-Prey Interactions
Predators : Organisms that catch and consumed
other organisms
Prey : organisms that get consumed.
Top Predator : the organism within a food chain or
web that is not eaten by any other organism.
Predation
Predator – Prey Dynamics
Symbiosis
• When TWO or more species interact so
closely that one or more of them is
NECESSARY for the other’s survival.
• Examples:
Coral and zooxanthellae algae
Fig trees and fig wasps
Tape worms and humans
Fleas and hairy mammals
Mutualism
• Both organisms BENEFIT
from the interaction
Red billed oxpecker feeds on
the ticks
Off the Impalas coat (Africa)
Coral and Zooxanthellae
Clownfish and Sea Anemone
Crocodile and plover mutualistic
relationship. Plover cleans
crocodiles teeth.
Commensalism –
• one IS HELPED but the
other is NOT harmed
• Ex. Birds nest in trees
Parasitism
One
organism
BENEFITS
• The other is
HARMED
Predator Prey Co-evolution
• Protection from Predation (for prey)
– Poison : the production of toxins
– Camouflage : protective coloration
– Mimicry: look alikes
• Adaptations to overcome protections (for
predators)
– Intolerance to poisons : immunity
– Use of senses other than sight: hearing, smell
Co-Evolution
• Predator /prey interactions
POISON IVY – protected from herbivores
WARNING coloration
says, “Don’t mess with
me !!”
Camouflage
PROTECTIVE
coloration
catipillar
Stick insects found in Australia
Mimicry
• Similar colors
• Similar DEFENSES
Wasp
bee
Mimicry- Fooled Ya!
• King snake
(not poisonous)
Red next to yellow
you’re a dead fellow
Coral snake
(VERY poisonous)
Ecological Succession
• The natural progression of SPECIES and
their EFFECTS on the environment
• PIONEER Species – the first to invade a
new environment (bare rock)
• MODIFICATIONS by the first group leads
to the second, the second the third, etc.
• The CLIMAX species will end the
succession.
Forest Succession
Lake Succession
• LAKE community
• Sedimentation due
to EROSION
• SWAMP
community forms
• Eventually a
FOREST
community may
form
Nutrient Recycling
•
•
•
•
Carbon and Oxygen: CO2, O2 (AIR)
Water: H2O (SOLID, LIQUID, GAS)
Nitrogen: N2 (AIR)
Other Minerals : MAGNESIUM, CALCIUM,
IRON, ZINC, COPPER, SILICA, ETC.
Carbon Cycle
• Atmospheric CARBON DIOXIDE
• Autotrophs CHANGE TO SUGAR
C6H12O6
• Heterotrophs CHANGE TO CO2 AND
ORGANIC MATERIALS.
• Decomposers BREAK DOWN ORGANIC
MATERIALS TO CO2
• Burning of FOSSIL FUELS
Water Cycle
• Evaporation LIQUID TO WATER VAPOR
• Transpiration EVAPORATION THROUGH
PLANTS
• Condensation and Precipitation RAIN,
SNOW, SLEET, HAIL etc.
• Runoff and Groundwater INFILTRATION
• Liquid water on the surface LAKES,
STREAMS, OCEANS etc.
Nitrogen Cycle
• Nitrogen in the Atmosphere N2 GAS
• Nitrogen Fixers BACTERIA ON PLANT
ROOTS
• Plants and Animals PROTEINS, UREA
• Decomposers PRODUCE AMMONIA
• Nitrifying Bacteria NH4 -> NO2, NO3
• Denitrifying Bacteria NO3-> N2 GAS
Other Minerals
•
•
•
•
•
•
Rocks and Soil CONTAIN MINERALS
Erosion RELEASES MINERALS
Water dissolves MINERALS
Plants and Algae uptake MINERALS
Animals consume PLANTS AND ALGAE
Decomposers LEAVE MINERALS IN SOIL