Transcript Primary succession is

Community
Ecology
© Amy Brown, Science Stuff, May 2012.
All rights reserved by the author
Community Interactions
Community:
A community is all of the living
organisms found in a particular
area.
When organisms live
in communities, they
_______
interact constantly
and have a powerful
effect on the
_________.
ecosystem
Different types of community
interactions include:
1.
2.
3.
4.
5.
6.
Competition
Predation
Symbiosis
Mutualism
Commensalism
Parasitism
Competition occurs
when organisms of the
same or different
species:
attempt to use the same
ecological resource in the
same place at the same
time.
What is a resource?
A resource refers to anything
that is required for life.
Resources might include:
food, water, light, nesting sites,
or room to grow.
When organisms are
competing for the same
resource, there is often a
winner and a loser
________________.
The winner thrives and the loser
fails to survive.
This is called the:
“competitive exclusion
principle.”
This invasive kudzu
smothers and strangles
any other plant in its path.
Competitive Exclusion Principle:
No two
species can
occupy the
same niche in
the same
habitat at the
same time.
In competitive exclusion one species is _________
eliminated from a
community because of __________
competition for the same
limited resource
_______________.
Usually one species uses the resource
eliminated
more _________,
efficiently and the other species is _________.
Occasionally, when two
species are
intense competitors
_________________,
one or both species may
evolve:
niche differences or
anatomical differences
that lessen the intensity
of the competition.
This phenomenon is
called character
displacement.
Example of character
displacement:
Finches have different size
_____ depending on the type of
beaks
seed they eat.
_____
Two species of finches that are
very similar to one another live
in the various islands making up
the Galapagos Islands.
When these two species live on ______________
separate islands and have no
competition with each other, they have the same _________.
beak size
__________
But on an island where both birds are found, their beak sizes are
________.
different
They have evolved a ____________________
character displacement that enables them to
feed on __________________.
different-sized seeds
Competition is reduced between the two species.
Competition is most intense between:
closely related species that require the same resources.
When similar species coexist, each species uses:
only part of the available resources.
This pattern of resource use is called resource partitioning.
Example of resource partitioning: There
are five different species of warblers
that live in spruce and fir trees.
They all feed on:
the same type of insects.
Each kind of warbler
hunts for insects only in:
a particular section of
the tree.
As a result, competition
among the three species
is reduced.
When can two similar
species coexist
successfully in the same
community?
Answer: Only when there
is enough difference in
their niches.
What are two possible outcomes of
competition between species having
identical niches?
Answer: Either the less competitive species will be
driven to local extinction, or one of the species may
evolve enough through natural selection to use a
different set of resources.
Predation
Predation is an interaction in which
one organism captures and feeds on
another organism.
The predator is:
the organism that
does the killing and
eating.
The prey is:
the food organism.
Predation is a powerful force in the community.
Predation determines relationships in _________
food webs and
population size
is a very effective regulator of _____________.
Natural selection favors adaptations that
make organisms….
…. better suited for their environment.
Predators have become more efficient
over time by developing _____
tools
(through natural selection) that make
them _____________.
better predators
Examples: Snakes have heat sensitive pits to
help them locate prey. Predators may have acute
senses, fangs, claws, poison, stingers, and sharp
teeth. Spiders have webs to catch their prey.
Just as the predator must be
highly adapted to catch the
food, the prey must have:
adaptations that help them
avoid being captured and
eaten.
a) The prey may have the ability to run very fast to escape the predator.
b) The prey may be camouflaged to avoid detection.
c) The prey may have poisons that are advertised by bright warning
colors.
Mimicry
Mimicry is a form of
deception used by the prey
as a means of defense
against being eaten.
Coral snake
In mimicry, a harmless
species resembles a
poisonous or distasteful
species.
The king snake is a mimic
of the very poisonous coral
snake.
King
snake
Monarch
The viceroy butterfly
mimics the monarch
butterfly.
Birds
avoid
eating
the
Viceroy
monarchs due to their
very bitter taste.
The viceroy does not
have a bad taste, but
since it resembles the
monarch, birds are
reluctant to eat it.
Herbivores are:
animals that eat plants.
This makes the herbivore a:
predator on plants.
Through natural selection, plants
have developed adaptations that:
protect them from being eaten by
animals.
Plants and Herbivores
Plants may have:
sharp spines, thorns, sticky hairs, and tough
leaves.
Plants may also produce:
chemical compounds that are poisonous, or bad
tasting.
Can you give an example of each of the
predator-prey combinations listed in the
table below?
A lion kills and eats a zebra.
The zebra grazes on grasses.
Athlete’s foot or ringworm.
A strep infection.
Blights and mildews.
Symbiotic Relationships between Organisms
Symbiosis is a close and permanent relationship
between organisms of different species.
There are three types of symbiotic relationships:
• Mutualism
• Commensalism
•Parasitism
In mutualism:
both species benefit from the relationship.
This bird eats the ticks on the back
of the antelope.
Flowers and insects have a
mutualistic relationship.
The flower provides the insect
with ______,
nectar and the insect
helps the flower to reproduce
by spreading ______.
pollen
Termites have a
particular
bacterium that
lives in their gut.
The bacteria help to digest the
wood eaten by the termite, and
the termite provides the
bacteria with:
shelter, warmth, water, and
food.
Some mutualistic
relationships are so close:
that neither species can
survive without the other.
One such example is the ants that live in the acacia shrubs.
The ants nest inside the
acacia’s large thorns and
receive ____
food from the
plant.
The ants protect the
acacia from:
predation by herbivores.
Commensalism
Commensalism is the relationship between two
different species in which:
one species benefits from the relationship. The other
species is neither harmed nor helped.
The large fish seen here is
called a triggerfish. The
triggerfish is able to move
large rocks that create
feeding opportunities for
the smaller fish. There is
no benefit to the
triggerfish.
Barnacles are mollusks that attach to the
skin of whales.
The barnacle does not ____
hurt the whale nor
help the whale.
does it ____
The barnacle is a
filter feeder and
benefits from
________
the constant flow
of water.
Parasitism is the
relationship between:
two different species in
which one species is
helped and the other
species is harmed.
Parasitism
tapeworm
nutrition
The parasite obtains its _________
host
from the other organism, the ____.
flea
Ectoparasites are…..
…..external parasites.
They live on their host but
___________
do not enter the host’s body.
Examples
include:
ticks, fleas, and
lice.
Endoparasites are…..
…..internal parasites.
These live ______
inside the host’s
body.
Examples include:
Some bacteria, some protists, and intestinal worms
such as tapeworms.
This is the number of different
species found in the
community.
Community 1 has greater species diversity.
This is the relationship between the number of
species in the community to the relative
abundance of each species.
Species richness varies
latitude
with _______.
Species richness is greatest in the tropical rain forests.
As a general rule, the closer a
equator the
community is to the _______,
more species it will contain.
____________
A pattern of
species
richness is that:
larger areas
usually contain
more species
than smaller
areas do.
This relationship is called the species-area effect.
Why does species richness increase with
increasing area?
Larger areas usually contain a greater diversity
of habitats and thus can support more species.
There is a very important consequence
of the species-area effect.
Reducing the:
size of a habitat reduces the
number of species it can support.
___________________
Habitat destruction
by an ever-growing
human population is
occurring at a faster and
faster rate each day.
Currently, about ____
2% of
the tropical rain forests
are destroyed each year.
The extinction of
species!!
What is the
result of habitat
destruction?
Disturbances
A disturbance is:
an event, such as a
storm, fire, flood,
drought, overgrazing,
or human activity that
changes a community
by removing organisms
from it or altering
resource availability.
Human activities that cause the greatest
disturbance to communities include:
Agricultural development
Logging and clearing
Mining and farming
Succession is:
the gradual, sequential regrowth of an area
following a disturbance.
There are two types of succession:
 Primary succession
 Secondary succession
Primary succession is:
the development of a community in an area
that has not previously supported life.
Primary Succession
Examples might
include:
a bare rock, a sand
dune, or an island
formed by volcanic
eruption.
Primary succession
often occurs very
______
slowly because:
the minerals
necessary for plant
growth are
unavailable.
Over time, rocks will
begin to break down
due to __________.
weathering
Lichens are
usually the first to
colonize these
barren areas.
(A lichen is the
mutualistic
relationship
between an algae
and a fungus.)
The combination of
________
minerals from rocks, and
the __________________
dead organic matter
from the lichens will begin
to form a thin layer of ____
soil
in which a few__________
grass-like
organisms can grow.
As these plants die, they
add more decayed organic
matter to the soil and soon
a few shrubs will appear.
The shrubs are then
followed by trees.
This is:
the replacement of species that follows a
disturbance in an already existing community.
Secondary Succession
The disruption may occur from:
a natural disaster such as a forest fire or a
strong storm, or from human activities such
as clear-cutting, mining or farming.
The
disturbance
has left:
the existing
soil intact.
Pioneer Species
These are the
organisms that are
generally the first to
colonize the area.
They appear:
early in succession.
These organisms tend to be:
small, fast growing, and very
fast at reproduction.
These organisms have:
adaptations that make them well suited to
invading and occupying a new area.
For example, they may be very good at seed
dispersal, or have adaptations that allow them
to withstand harsh conditions.
Climax
Communities
In succession, the community
proceeds through a series of
stages until it reaches:
a stable end point called the
climax community.
The organisms in each stage of succession
physical environment in ways that
alter the __________________
make it ____
less favorable for themselves but
more
____ favorable for the organisms that follow.
The climax
community:
remains
constant for a
long period of
time.
Succession in a Marine Ecosystem
(Whale-Fall Community)
The deep dark ocean floor is a:
barren, inhospitable
environment.
Succession can take place even in
this environment when a
__________
disturbance occurs.
The disturbance begins when:
a large whale dies and sinks to
the barren ocean floor.
The whale carcass attracts:
many scavengers and decomposers that
begin to feast on the decaying carcass.
Within a year, most
of the whale’s
tissues will have
The decomposition
____________ of the carcass
______
has enriched the surrounding
been _____
eaten and
sediments, attracting:
only a much smaller
a new population of sediment
community of
dwellers such as marine worms.
organisms:
can be supported.
When only the skeleton remains…..
…..a third community moves in.
Heterotrophic bacteria begin to:
decompose oils inside the whale bones.
This releases
chemical
compounds that
can be used by:
chemosynthetic
bacteria.
The chemosynthetic bacteria can
support a diverse community of:
mussels, snails, worms, crabs, and
clams.