Download Community Ecology

Community Ecology
All interactions between biotic factors that
can impact an ecosystem
Community Ecology Basics
❏ Population: One
species in a specific
area
❏ Community: All biotic
factors in a specific
area
❏ Ecosystem: All biotic
and abiotic factors in
an area
Community
Members
Producers: organisms that
produce their own food
through photosynthesis or
chemosynthesis
Autotrophs
Community
Members
Consumers: Organisms that
consume their food
Heterotrophs, Detritivores
Carnivores, Omnivores,
herbivores
Primary, secondary,
tertiary, etc...
Community
Members
Can be organized into
TROPHIC LEVELS
Trends of survivorship can
be found in Trophic levels
BIG IDEA
Community Ecology is the study of
interactions between Community Members
Types of Interactions - Competition
Types of Interactions - Competition
Organisms attempting to use the
same resource
Mates, food, territory (any
need that must be filled for
life)
Intraspecific Competition:
between same species
Sexual selection
Interspecific Competition:
between different species
Types of Interactions - Competition
Competitive Exclusion
Principle: no two species
can occupy the same niche
Niche: organism’s role in an
ecosystem
Includes habitat, food
source, behavior (the
sum of all biotic and
abiotic interactions
of an organism)
Types of Interactions - Competition
Result of Competition and CEP:
Population control
Extinction
Behavioral shift of one species
Long term evolutionary shift of
one species
Character Displacement
If two similar species
geographically overlap
Types of Interactions - Competition
Result of Competition and CEP:
Population control
Extinction
Behavioral shift of one species
Long term evolutionary shift of
one species
Character Displacement
If two similar species
geographically overlap
Types of Interactions - Predation
Types of Interactions - Predation
One organism hunts and eats
another
Population growth can be
affected by predation
Predator / Prey Population
Density Cycles
One population’s growth
responds to the other
Types of Interactions - Predation
Apex Predator: predator at the
top of a food chain on which
no other predators prey
upon.
Mesopredator: Mid-level
predator that preys upon and
is preyed upon
Types of Interactions - Predation
Types of Interactions - Predation
Predation causes physical
adaptations to both
predator and prey due to
natural selection
Types of Interactions - Predation
Prey Adaptation
Tend to be community
oriented herd animals
Physical defensive and
offensive adaptations
Adaptations specific to
prey’s environment
Eye placement
Coloration
Types of Interactions - Predation
Prey Adaptation
Cryptic Coloration:
Camouflage
Aposematic Coloration:
indicates chemical
warnings and defenses
(poison)
Types of Interactions - Predation
Prey Adaptation
Batesian Mimicry: a
harmless species look
like a harmful one to
avoid predation
Mullerian Mimicry: two or
more distasteful
species, mimic each
other’s warning signals
Do not have to be
Types of Interactions - Predation
Predator Adaptation:
Can be pack hunters or
solo hunters
Acute senses
Physical Adaptations
Eye placement
Teeth
Feet
Types of Interactions - Herbivory
Types of Interactions - Herbivory
Type of predation in which
autotrophs are eaten
Also results in
defensive adaptations
due to natural
selection
Types of Interactions - Herbivory
Adaptive Results of
Herbivory
Mechanical defense such as
thorns and needles
Masting: producing more
offspring than an
animal can consume
Chemical defense that can
include
Taste
Types of Interactions - Symbiosis
Types of Interactions - Symbiosis
A close and often long term
interaction between two
different species
Mutualism
Commensalism
Parasitism
Feeding relationships do
not qualify as they are
not long term
Types of Interactions - Symbiosis
Mutualism: Both species
benefit from
relationship
+ / +
Flowers and insects
Nemo and the Anemone
Result can be in
increase in
population
Types of Interactions - Symbiosis
Commensalism: one member
benefits while the other is
neither helped nor harmed
+ / 0
Egrets and Water Buffalo
Result can be an increase
or stabilizing effect on
one population and no
effect on the other
Types of Interactions - Symbiosis
Parasitism: One organism lives
in or on another and harms
it in order to get what it
needs to live
+ / -
Ticks and mammals
Result can be a limitation
of one species
population
A Big Idea
Community
Interactions can
shape and impact an
ecosystem in both
positive and
negative ways.
Impact Through
Trophic
Interactions
Impact Through Trophic Interactions
Dominant Species
Species in a community that
are the most abundant in
number or biomass
Biomass = the total mass
of all individuals in
a population
Impact Through Trophic Interactions
How do species become dominant?
Superior in exploiting
resources
Successful avoidance of
predators or disease
Affects community by decreasing
biodiversity or providing
niche for other species
American Chestnut Tree
Impact Through Trophic Interactions
Keystone Species
Species that have a strong
control over an ecosystem
Not based on numbers or
biomass
Affects community by having
large impact on other
species
Impact Through Trophic Interactions
Keystone Species
Species that have a strong
control over an ecosystem
Not based on numbers or
biomass
Affects community by having
large impact on other
species
Impact Through Trophic Interactions
Foundation Species
Ecosystem engineers that
impact trophic levels by
providing habitats and
niches for other species
Positively affect the
reproduction and
survival of other
species
Changing Communities by
changing trophic levels
Top Down and Bottom Up Models
Trophic Level Manipulation
Bottom Up Model: Biomass
is altered at the lower
trophic levels, allowing
changes to move up the
food web
Top Down Model: Biomass is
altered at the top
trophic levels, allowing
changes to move down the
food web
Adding minerals to vegetation
to stimulate growth
Introducing a predator to
control population of lower
levels
Trophic Level Manipulation
Limits on Trophic Structure and Food Chain Length
Food Chain: transfer of
food energy up trophic
levels from source to
eventually decomposers
Rarely more than 7 links
Most have 5 or fewer
Why?
Limits on Trophic Structure and Food Chain Length
Energetic Hypothesis:
Inefficiency of energy
transfer along trophic
levels
Only 10% is transferred
Producer level consisting of
100 kg of plant matter can
support 10 kg of herbivore
biomass
This model predicts longer
food chains in areas of
Limits on Trophic Structure and Food Chain Length
Dynamic Stability
Hypothesis: long food
chains are less stable
than short ones
Population fluctuations at
lower trophic levels are
magnified at higher levels
Cause potential
extinction of top
predators
Limits on Trophic Structure and Food Chain Length
Dynamic Stability
Hypothesis: long food
chains are less stable
than short ones
Population fluctuations at
lower trophic levels are
magnified at higher levels
Cause potential
extinction of top
predators