Download Ch 54 notes with additions from 55-56

AP Bio Ch 54
Community Ecology: the study of the
interactions among all the
populations in an ecosystem.
Interactions within a Community
Interspecific Interactions include:
•
•
•
•
Competition (-/-)
Predation (+/-)
Herbivory (+/-)
Symbiosis
– Parasitism (+/-)
– Mutualism (+/+)
– Commensalism (+/0)
• Facilitation (+/+) or (+/0)
Competition
• A contest between individuals
for shared resources. (-/-)
interaction.
• Between species (interspecific)
or within a species
(intraspecific).
• All of an organism's
interactions in its environment
are known as its Niche
• Competition limits an
organism's niche.
• Fundamental niche: maximum
possible niche.
• Realized niche: actual niche.
Removal of Balanus barnacles demonstrates the
difference between the fundamental and realized
niche of Chthamalus barnacle
Effects of Competition
• Competitive Exclusion: When two species have
overlapping niches, one will out compete the other.
Remember this
lab???
Effects of Competition: Resource
Partitioning
• Competition drives species with overlapping
niches to adapt to non-overlapping resource
pools.
Effects of Competition: Character
Displacement
• The process by which
traits evolve in response
to selection to lessen
competition.
Together, they could be
distinguished unequivocally by
beak size.
Alone the beak size was
intermediate in size relative to
when the two co-occurred.
Predation
• One species (the
predator) kills and eats
the other species (the
prey).
• +/- interaction.
• Predation drives many
adaptations.
Effects of Predation (Defensive Adaptations)
Video
Coloration
• Cryptic: Camouflage or
other coloration that
confuses predators
Mimicry
• Aposematic: Warning
coloration, advertising a
threat to predators
• Mullarian: Two or more
harmful species with
common predators mimic
each other.
• Batesian: A harmless
species mimics a harmful
species.
Venomous
Coral snake
Video
Herbivory
• One species (the
herbivore) eats part of a
producer (plant or
algae)
• +/-interaction
• Producers have evolved
many adaptions to
control herbivory.
Symbiosis
• Parasitism
– The most
common
– +/– Animation: Very gross!
• Mutualism
• Commensalism
- +/0
– Everyone Wins!
– +/+
Facilitation
• Species have positive
effects on other species
in the community
without being in a
symbiotic relationship.
• +/+ or 0/+ interaction.
• Examples:
– Lichens
– Beavers
Disturbances to the Community
Structure
• Disturbances are things that remove
organisms or change recourses
availability…they include:
– Human Activities
– Storms
– Fire
– Drought
– Floods
Disturbances are not always bad!
The intermediate disturbance
hypothesis states that moderate
levels of disturbance can foster
greater species diversity.
Ecological Succession
Transitions in Species Composition
Primary Succession
• Life invading a region that
was virtually lifeless and
were soil has not formed
yet.
• Ex: Newly formed volcanic
island and a landslide
exposing new rock
Secondary Succession
• Occurs when a disturbance
clears the existing
community but the soil is
left intact.
• Ex: Wild fires and
abandoned farms
Energy Transfer in a Community
• Energy is transferred through the Food Chain!
– Trophic Levels show the feeding relationships in a
community.
– Energy flows from the SUN to the producers, who
are the 1st level of any food chain.
– Food chains tend to have no more than 4 or 5
tropic levels due to the inefficiency of energy
transfer.
– Decomposers/detritivores connect at every level.
Primary Productivity
• This is the amount of chemical energy
produced from light energy in photosynthesis.
• GPP: Gross meaning the TOTAL primary
productivity in an ecosystem.
• NPP: Net meaning what energy is left after the
plants use it for respiration.
• Formula: NPP = GPP-respiration
Energy Pyramid
Where does this energy
go??
• Energy is lost through
the cost of living:
• Cellular Respiration
50%
• Waste
production/removal
33%
• Growth 17%
***only this energy
can move on to the
next level in the food
chain
A.
B.
C.
D.
14,000
180
35
100
Other Ecological Pyramids
Biomass Pyramid
Pyramid of Numbers
The species in a community with the highest biomass or are
the most abundant are called the
Trophic Structure and Species Diversity
• A community with an even species
abundance is more diverse than one
that has a few abundant species and
the others are rare.
• Keystone species hold such an
important role in their niche that they
have control over the
structure of the community.
• Categories of Keystone Species
Keystone Species Animation
Biochemical Cycles
• You NEED to know how changes in these
cycles could change an ecosystem.
• Important note!
– Matter Cycles
– Energy does not!
Biodiversity and Threats
• Remember a more biodiversity means are more
stable community.
– Diversity can refer to…
• genetic diversity
• species diversity
• ecosystem diversity
• Threats include:
•
•
•
•
Habitat Loss
Introduction of new species
Over Harvesting
Global Changes
Human Interventions for the GOOD!
• Bioremediation
– Using bacteria, fungi,
or plants to clean up
pollutants.
• Bioaugmentation
– Introducing a species to add needed nutrients to
an area.