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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 (animals, plant, microbes)
• AUTOTROPHS (produce food) plants
• HETEROTROPHS-(need to get food)
consumers- (eat )
Decomposers-(breakdown organics)Bacteria, fungi
• A scavenger (vulture) is not a decomposer because
they are not returning nutrients to the soil
• 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
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 :occurs when individuals
in a population reproduce at a constant rate. (in
natural populations this does not occur for very
long)
• 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 for an emergency food source.The Island is off the coast
of Alaska in the Bering Sea. 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
• Competition- when populations require
use of limited resources
• Predator/prey- when one population
depends upon another for food
• Symbiosis- when two populations Niche
– Coincide with each other
• Competition- Resource food or population
may overlap
Predator-Prey Interactions
Predators : Organisms that catch and consume
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(only way fig tree is pollinated. Fig enters fig
and deposits eggs and pollen she brought along from another
fig)
Tape worms and humans (from undercooked meat, mostly
pork.Live inside your intestines.Can grow 50ft long and live up to
20 years inside you)
Fleas and hairy mammals
Bed Bugs-Feed at night on unsuspecting Humans
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
Hermit crab with
Sea Anemone living
on it
Parasitism
One
organism
BENEFITS
Malaria
• 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
caterpillar
Stick insects found in Australia
Mimicry
• Similar colors
• Similar DEFENSES
Wasp/yellow jacket- no hair-keep stinging you
Bee-hair on-some don’t sting others do.
Mimicry- Fooled Ya!
• King snake
(not poisonous)
If red touches yellow
you’re a dead fellow
If red touches black you’re a
fine Jack
Coral snake
(VERY poisonous)