Transcript Biodiversity and Ecosystem Stability

Biodiversity and Ecosystem Stability
1.
2.
3.
4.
Which organism will have the lowest
energy? Explain how you know.
Which organism will have the highest
biomass? Explain how you know.
If the blue bird consumes 100 J of
energy, how much energy will the eagle
be able to get from eating the blue
bird?
CHALLENGE! If the grass provided 367 J
of energy, how much energy will the blue
bird get? What about the eagle that eats
the bird?
Objectives
By the end of today, all SWBAT…
 Explain why biodiversity is
essential to the survival of
organisms using food web models
Agenda
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Catalyst Review
Evolution Test Class Averages
Homework Review – We got it!
What is biodiversity?
Ecosystem stability
Stations
Exit Question
on
Evoluti
2:
3:
4:
test class averages
72.6
67.9
66.0
47 - 91
29 - 100
27 - 93
Homework Review
5. Which of the following statements
are true?
a.
b.
c.
d.
The energy content of the iguana
depends on the energy content of the
rabbit
The energy content of the bird is
transferred to the snail
The energy content of the eagle
depends on the energy content of the
iguana
All of the above are true
Homework Review
6. A forest fire kills all the snails in the area.
The number of birds will… (circle one)
go extinct OR increase OR decrease OR no change
7. A group of raccoons enter the ecosystem and
eat all the worms. The number of iguanas will…
go extinct OR increase OR decrease OR no change
8. The animal is most directly impacted by a change in the
population of eagles is the…
iguana OR plants OR worm OR snail
Homework Review
Animal
Eagle
Iguana
Worm
Population
4
400
15,000
16. Which group of organisms will you expect to have
the largest biomass? Explain your reasoning.
17. Using your answer from above, which group of
organisms will you expect to have the largest
amount of energy? Make sure to explain the link
between energy and biomass.
18. If a worm consumes 247 Joules of energy, how
much energy will the Iguana receive when it eats
the worm?
Biodiversity Definition
Biodiversity = number of different
species that live in an ecosystem
Low
biodiversity: few species
High: many species
Low
Biodiversity
High Biodiversity
Low or High Biodiversity?
Low or High Biodiversity?
Low or High Biodiversity?
Low or High Biodiversity?
Low or High Biodiversity?
Benefits of Biodiversity

Key Point #1: There are three main
benefits to biodiversity
Many
people find nature beautiful
Provides medicines
Preserves ecosystem stability
Ecosystem stability… What?
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Stable = things stay the same
Key Point #2: High biodiversity = stable
ecosystem, low biodiversity = unstable
ecosystem
 If
an ecosystem is unstable, one small change
could cause many species to die
 If an ecosystem is stable, it does not change
easily
Ms. S, show me another way to
write that!

Key Point #2: High biodiversity = stable
ecosystem, low biodiversity = unstable
ecosystem
 CHANGE!
of species die  Unstable
 Most species don’t change  Stable
 Lots
This food web has low biodiversity
Rabbits eat grass. Foxes eat rabbits
Foxes
Rabbit
Grass
This food web has low biodiversity
A disturbance hits…
A drought happens and kills all the grass.

Foxes
Rabbit
Grass
This food web has low biodiversity

What happens to the foxes?
How many species do we have left?
0!
BIG change?
Grass
Rabbit
Foxes
This food web has high biodiversity
Let’s add a few more species to our original
ecosystem
Foxes
Lettuce
Rabbit
Chickens
Grass
This food web has high biodiversity
A disturbance hits…
A drought happens and kills all the grass.

Foxes
Lettuce
Rabbit
Chickens
Grass
This food web has high biodiversity
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The
food
web started
with high biodiversity
What
happens
to the foxes?
High biodiversity = stable ecosystem
Population size decreases… a little
One change… didn’t really do anything!
Foxes
Lettuce
BIG change?
Rabbit
Chickens
Grass
Comparing Multiple Ecosystems
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Key Point #3: If we have two ecosystems, the
one that CHANGES LESS is the one with HIGHER
BIODIVERSITY
Let’s try this idea out…
Ms. S shoots all the bears in two forests. In the first
forest, everything dies as a result. In the second forest, a
couple of animals die, but things remain mostly the same.
 Which has higher biodiversity?
 Which is more stable?
Stations (GP)

Practice your new knowledge!
6
stations
 7 minutes for each station
THINK about what you’re reading and what you’re
drawing. Really. Think. Seriously.
Work
hard. Talk when you’re
finished, not before.
Stations Review (GP)
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Any questions?
Closing

There are three primary benefits to biodiversity
 Beautiful,

An ecosystem is stable if it does not change easily
when disturbed
 “Change”

medicines, ecosystem stability
= number of species that live there
We can figure out which of two ecosystems has
higher biodiversity based on how stable each one is
 More
stable = higher biodiversity
 Less stable = lower biodiversity
Exit Questions
Answer BOTH in complete sentences
Read the passage at right to
answer the questions below:


How does trawling affect
coral reef biodiversity?
Would the coral reef be
more or less stable after
trawling? Explain why,
and be SPECIFIC.
(Hint: describe what
happens to all the
organisms in the coral reef
ecosystem, and use the word
“biodiversity.”)
Many organisms live in coral reefs, such
as plankton and algae, hundreds of
species of fish, sea urchins, and eels.
All of these organisms depend on
the coral to survive: they live inside
of it, use it for shelter, eat it, etc.
Trawling is the process of dragging a
gigantic rake across the bottom of
the ocean floor to scoop up
organisms. This is a very good way
to catch fish, but has the unfortunate
side effect of destroying nearly all
the coral in the trawler’s path.