Download Biology Chapter 4-1 Ecosystems and Commun

4-2 What Shapes an Ecosystem?
A.
Ecosystem conditions:
1. Biotic factorsbiological influences on
organisms within an
ecosystem.
a. Examples: plants,
bacteria, and animals.
2. Abiotic factors- nonliving or physical factors that effect
the ecosystem
a. Examples:
temperature,
precipitation, wind,
soil type and sunlight.
3. habitat- the area were an organism lives, it includes both
biotic and abiotic factors.
4. niche- the job of an organism, it too includes biotic and
abiotic factors, the full range of conditions in which an
organism lives and the way in which the organism uses those
conditions.
B. Community interactions:
1. competition- when organisms of the same or different
species attempt to use an ecological resource in the same way
at the same time. There is usually a winner and a loser that
does not survive.
a.
resource- anything that is needed to survive
b. competitive exclusion principle- states that no two
species can occupy the same niche in the same habitat at the
same time.
Blue Warbler
Feeds at the tips of branches
near the top of the tree
Bay-Breasted Warbler
Feeds in the middle
part of the tree
Spruce tree
X
Cape May Warbler
Feeds at the tips of branches
near the top of the tree
Yellow-Rumped Warbler
Feeds in the lower part of the tree and
at the bases of the middle branches
2. Predation- an interaction in which one organism
captures and feeds on another organism.
a. Predator- the animal that captures and feeds on another
animal
b.
Prey- the animal that is hunted and eaten by a predator
3. Symbiosis- a
relationship in which two
species live closely
together—3 types
a. Mutualism- both species benefit from the symbiotic
relationship.
1)
Example:
a) flowers and bees:
the flower benefits by
being pollinated and the
bees benefits by getting
food (nectar and pollen)
b) termite and the flagellate;
the termite get nutrients from
the wood that the flagellate
digests and the flagellate gets a
home and is feed by the
termite.
c)
Ants and aphids
d)
algae and fungus living together form a lichen
b. Commensalism- one member of the relationship
benefits and the other is nether helped nor harmed.
1)
Examples:
a) barnacles attached to a whale’s skin: whale is not hurt or
helped by the barnacles, barnacles benefit from the constant
movement of the water which carries food particles.
b) A remora (a small fish with a suction disk on the top of
its head) hitches a ride with a large sea animal such as a sea
turtle or a shark. This benefits the remora by being taken to
its next meal without having to spend energy to swim and
hunt. The shark or turtle isn’t hurt but doesn’t benefit either.
c)
Orchids and trees
d)
Lichen and trees
e)
Hermit crabs and other mollusk’s shells
c. Parasitism- one organism lives on or inside another
organism and harms it. The organism that benefits is called
the parasite, the other organism is called the host. Usually the
parasite weakens, not kills, the host.
1)
Examples:
a)
tapeworms that live inside their host organism.
b) Fleas, ticks, lice, leeches, flukes and even mosquitoes
living on mammals for their skin and blood.
c) Some molds (water molds on fish), some fungi
(athletics foot, ringworm, tree fungi) are parasites.
C.
Ecological Succession
1.
ecosystems are constantly changing.
a.
in response to natural changes
b.
and human disturbances
2.
ecosystems go through a predictable series of changes.
a.
Older inhabitants die out and
b.
new organisms move in producing additional changes.
3.
ecosystems change
a.
slowly as changes occur over time or
b.
quickly in response to disasters
4.
Succession
a. Primary succession- succession that occurs on surfaces
where no soil exists. The surface is rock or ash, typical of a
volcanic area.
1) The first organisms to grow in the area are called
pioneer species.
a) Lichens- these organisms actually help to break
down the rock with enzymes from their rhizoids. This
broken rock is the beginning of soil. As soil is
produced—the surface begins to change—other plants
will now be able to live in the area.
Mosses on rock
Lichens on rock
Grasses and other plants
growing in thin layer of soil
over rock layers
b. Secondary succession- occurs when a disturbance of
some kind changes the community without removing the soil.
This often occurs after a plot of farmland has been abandoned
and begins to grow wild.
After a forest fire, the forest will start to re-grow.
Mt. Saint Helen’s
forest at 3 month, 9
years, and 14 years
after the 1980 volcanic
eruption.
Climax community- As areas proceed through the stages of
succession, eventually a mature, stable group of organisms populate
the area. This community seems stable and maintains itself over a
long period of time. However, the environment is constantly
changing and even the climax community changes in response to
subtle changes through time.