Transcript Ecosystems

Ecosystems
Interactions among living things
Natural Selection:
A process by which characteristics that
make an individual better suited to it's
environment become more common in
the species.
 Sometimes referred to as “survival of
the fittest”

How Does Natural Selection work?
1.
2.
Those with the unique characteristics best
suited for their environment will survive and
produce offspring.
End result = ADAPTATIONS
English Peppered Moth –Natural
selection in action
dark moth - random mutation
not as common
camouflaged moth
Soot covered tree
England 1800’s
Adaptations

Behaviors or physical characteristics that
allow organisms to live successfully in
their environment
Shell for
protection
Long neck to
reach leaves
Long shallow
roots, needles
to protect from
animals
Niche


An organisms’ role in an ecosystem = niche.
Niche and Habitat are different
◦ Address of an organism = Habitat
◦ “Job” or “Profession” = Niche
Organism = tree
Habitat = Forest
Niche = produce oxygen
provide home for birds
Explain why two organisms
cannot occupy the same niche:

If two species occupy the exact same
niche in nature, one will die off due to
competition for limited resources.
Video Link – Niche, Competition, Predation, and Symbiosis
http://www.youtube.com/watch?v=D1aRSeT-mQE
Three major types of
interactions among organisms:
Competition
 Predation
 Symbiosis

Competition:

The struggle between
organisms to survive as they
attempt to use the same
limited resources.
Predation:
 An
interaction in which
one organism kills
another for food.
Predator or Prey:
Predator - organism that does
the killing
 Prey – organism that is killed.

Effect of predation on population size:
What variable is
plotted on the
years
x-axis? ______
 What two variables
are plotted on the
# of moose
y-axis? ________
# of wolves
and __________

Effect of predation on population size:

How did the moose
population change
between 1965 and
It increased
1972 ___________

How did the wolf
population change
between 1973 and
It increased
1976? __________
Effect of predation on population size:

How might the
change in moose
population have lead
to the change in wolf
population?
– The wolf preys on
the moose so more
moose meant more
food for the wolf.
Effect of predation on population size:

How might disease in
the wolf population
one year affect the
moose population the
next year?
– Disease in the wolf
population might
cause some to die.
With less predators,
the moose
population would
most likely increase.
Examples of Predator Adaptations
 Cheetah
speed
 Owl eyes
 Jelly fish venom
Defense Strategies of Prey
Mimicry
 Protective Covering
 False Coloring
 Warning color
 Camouflage

Video Link on Predator and Prey Interactions
http://www.youtube.com/watch?v=vZynrBA91fY
Interactions – Three Types
Symbiosis – a close relationship in nature
that benefits at least one species
Bacteria from gut of termite
Termites
Symbiosis
Mutualism

Both species benefit
Commensalism

One species benefits, but the other isn’t
harmed or helped.
Parasitism
One species benefits and the other is
harmed.
 The one benefiting is the parasite
 The one being harmed is a host
