Download Ecology 1- Notes

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Ecology I
Main Idea: the interactions between Organisms and
their interactions with the Environment
A. Ecology (Definition) – the study of how
organisms interact with the living and
nonliving things that surround them.
1. The fundamental concept of ecology is
that all living things are dependent
on each other and they interact
with
one another and with the physical
environment.
2.
Environment
(Definition) –
every living and nonliving thing that
surrounds an organism.
B. Parts of an Ecosystem
1. Ecosystem (Definition) – all the living
and nonliving things that interact in a
specific area.
I.e. pond, field of corn, fish tank,
woodland, ocean or a decaying log.
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a.
Biotic
– the living
environment.
Factors (Definition)
parts of the
I.e. bacteria, plants and animals.
b.
Abiotic
Factors (Definition)
– the nonliving parts of the
environment.
I.e. soil, water, physical space
and energy.
2.
Habitat
(Definition) – the
“home” of a particular species.
i.e. fields, forests, oceans, streams
and deserts.
3.
Population
(Definition) –
the individuals of a species that live in
the same area.
i.e. ants in a single anthill,
squirrels in the town of Lancaster, or
worms in the courtyard.
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4.
Community
(Definition) –
different populations in a given area
combine to form a community.
I.e. all the dogs, cats, people,
squirrels, birds (etc.) in the town of
Lancaster.
5.
Biosphere
(Definition) – all
of the earth’s ecosystems
(any portion of the earth, including all
of the water, land, and air in which
organisms survive.)
a. Throughout the biosphere, organisms
interact and compete for vital
resources, such as
food
,
space
, and
shelter
.
C. Environmental Limits on Population Size
1. The growth and survival of organisms
depends on the physical conditions and on
the
resources
available to the
organism.
2. If they had unlimited
resources
, living things could produce populations
of infinite (unlimited) size.
3. Within any ecosystem, however,
resources (oxygen, carbon dioxide,water,
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nutrients, space, and sunlight) are
finite (
limited
).
4. Because the resources are limited,
organisms must compete with one another
to survive.
a. Competition (Definition) – the
struggle for resources among organisms.
b. Within any one species,
competition
keeps the size of
that species’ population balanced.
c. Populations tend to increase or
decrease depending on the resources
that are available at the time. Over
long periods of time, however, the size
of the population remains
stable
.
5. Limiting Factors (Definition) –
anything that limits the size of a
population.
a. Limiting factors can be abiotic
(nonliving):
1.
Abiotic
factors, such as
the amount of dissolved oxygen in a
pond, may limit the kinds and
numbers of fish that can live
there.
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2.
Abiotic
factors, such as
the amount of sunlight filtering
through a forest may limit the
number of green plants living on
the forest floor.
3. Other limiting factors that are
abiotic
include the intensity
of light, the temperature range in
the environment, minerals that are
available in the water or soil, or
the type of rock or soil in the
ecosystem.
b. Limiting factors can also be biotic
(living):
1. An important
biotic factor
that limits population sizes is the
relationship between predators and
prey.
a.
Predator (Definition) –
kill and eat other organisms.
b.
Prey(Definition) – killed
for food.
2. As predators kill and eat their
prey, they limit the growth of the
prey population.
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3. If too many prey animals are
killed, predators begin to starve
, and their population is reduced.
4. With fewer predators, the size
of the prey population begins to
recover
.
6. Carrying Capacity (Definition) – the
number of organisms of any single species
that an ecosystem can support.
a. Carrying Capacity of a species is
determined by available energy
,
water
,
oxygen , minerals
, and the
interactions of its
organisms
.
b. For example, a field’s carrying
capacity for a population of foxes is
affected not only by the
climate
, but also by the number and kinds of
other
populations present.
1. If there are many mice for the
fox population to eat, the fox
population may
increase
drastically.
2. If there are many viruses
affecting the foxes, their
population may
crash .
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3. The population of organisms in a
given area will increase until the
carrying capacity is reached.
There will be a quiz on this entire packet on
___________
There will be a TEST on this entire packet on
_________
.
.
Unit XII Ecology Notes [Notes2000 #7]