Download 3.1 notes - WordPress.com

3.1 How Changes Occur Naturally in Ecosystems
Name:_______________________
•
When an organism is born, it belongs to a
also is born with unique characteristics.
, but it
 Sometimes, these unique
organisms an advantage within their
give
.
 For example, a salmon with a slightly larger tail may be able to swim a
little faster or a little farther in a river.
•
Natural selection is the process where individuals with
are better able to reproduce and pass along their traits.
 Those with
reproduce and pass along their

_
characteristics have less chance to
.
A salmon with a smaller tail may never have a chance to spawn
because it cannot swim to the correct location.
How Organisms Adapt to Change
•
The Galapagos Islands, off the coast of Ecuador, are a famous example of
_
.
 Many species on these islands are very
to
each other but different from species on the South American continent.
•

There are 13 species of finches on the islands.

Each is descended from a finch species from the mainland.

Each species has unique
thrive in its own niche and not
other finches for resources.
Adaptive radiation describes the type of
many different species appear from
that allow it to
with
where
original species.
How Ecosystems Change Over Time: Primary Succession
refers to the changes in the
characteristics in an area over time.
•
_
 There are
types of ecological succession: primary
succession and secondary succession.
1. Primary succession begins with
glaciers scrape away dirt or a volcano erupts.
such as where
 Wind carries spores of
and organisms that can
survive and eventually, combined with the weathering of rock, help
form
.
 The first organisms to survive and reproduce are
_
.

Pioneer species alter the
environment in some way.

Soil improves, plants are able to
begin to
.
 Primary succession occurs in all parts of the
 This stage can last for
_
_
and
_
and animals
.
of years, until a mature _
eventually forms.
How Ecosystems Change Over Time: Secondary Succession
•
Mature
are very
can appear to be unchanging over long periods of time.
and
 These are also known as
communities, but
“mature” correctly implies that there are still changes occurring.
2. Secondary succession occurs after a major
an area that already has
in
and once had living organisms.
are the most common reason for

secondary succession.
 The soil
for plant growth and contains seeds, microorganisms, earthworms, and insects.
 Secondary succession is much more
than
primary succession because soil, seeds and insects are already present.
How Natural Events Affect Ecosystems
•
Many other disturbances can affect mature communities.
•
Flooding
 Water is not
within natural or artificial barriers.
 Floods generally occur in locations where water
change rapidly.
can
 Flooding can result in soil
as well as the spread
of pollutants and harmful bacteria associated with
.
 Climate change and
incidents of flooding.
 A tsunami occurs when huge
or volcanic eruptions flood coastal areas.
may be increasing
from large earthquakes
•
Drought
 Drought occurs when an area receives a
average amount of
than
over a long period of time.
 Prolonged drought can have severe effects on
•
.
Insect infestations
 Many
play important roles in their ecosystems.
 Even insects that appear
mountain pine beetle, actually play a role in the
the forest.

, such as the
of
The beetles have a
relationship with
a species of fungus that inhibits the trees’ ability to use resin for
protection.
 However, when
infestations can occur.
conditions are changed,

Trees can be stressed
from overcrowding
drought or animal grazing and do not resist the insects as
effectively.

A
climate and lack of forest fires allows the
insects to spread much more effectively than in the past.
 Not only are the
_
relying on the forest.
affected, but so is the entire forest
, as well as any human industries