Biodiversity-and-ecosystem-stability

1. Agenda
 Catalyst Review
 Evolution Test Class Averages
 Homework Review – We got it!
 What is biodiversity?
 Ecosystem stability
 Stations
 Exit Question

2. Biodiversity and Ecosystem
Stability
1. Which organism will have the
lowest energy? Explain how you
know.
2. Which organism will have the
highest biomass? Explain how
you know.
3. If the blue bird consumes 100 J of
energy, how much energy will the
eagle be able to get from eating the
blue bird?
4. CHALLENGE! If the grass provided
367 J of energy, how much energy will

3. Homework Review
5. Which of the following
statements are true?
a. The energy content of the iguana
depends on the energy content of
the rabbit
b. The energy content of the bird is
transferred to the snail
c. The energy content of the eagle
depends on the energy content of
the iguana
d. All of the above are true

4. 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

5. Homework Review
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?
Animal Population
Eagle 4
Iguana 400
Worm 15,000

6. Biodiversity Definition
Biodiversity = number of
different species that live in an
ecosystem
Low biodiversity: few species
High: many species

7. Low
Biodiversity

8. High Biodiversity

9. Low or High

10. Low or High

11. Low or High

12. Low or High

13. Low or High

14. Benefits of Biodiversity
Key Point #1: There are three
main benefits to biodiversity
Many people find nature beautiful
Provides medicines
Preserves ecosystem stability

15. Ecosystem stability… What?
 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

16. Ms. S, show me another way to
write that!
 Key Point #2: High biodiversity =
stable ecosystem, low biodiversity =
unstable ecosystem
CHANGE!
Lots of species die  Unstable
Most species don’t change  Stable

17. This food web has low
biodiversity
Rabbits eat grass. Foxes eat rabbits
Grass
Rabbit
Foxes

18. This food web has low
biodiversity
 A disturbance hits…
A drought happens and kills all the grass.
Grass
Rabbit
Foxes

19. This food web has low
biodiversity
 What happens to the foxes?
Grass
Rabbit
Foxes
How many species do we have left?
0!
BIG change?

20. This food web has high
biodiversity
Let’s add a few more species to our original ecosystem
Grass
Rabbit
Foxes
Chickens
Lettuce

21. This food web has high
biodiversity
 A disturbance hits…
A drought happens and kills all the grass.
Grass
Rabbit
Foxes
Chickens
Lettuce

22. This food web has high
biodiversity
 What happens to the foxes?
Population size decreases… a little
BIG change?
Grass
Rabbit
Foxes
Chickens
Lettuce
 The food web started with high biodiversity
 High biodiversity = stable ecosystem
 One change… didn’t really do anything!

23. Comparing Multiple
Ecosystems
 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?

24. 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.

25. Stations Review (GP)
 Any questions?

26. Closing
 There are three primary benefits to biodiversity
 Beautiful, medicines, ecosystem stability
 An ecosystem is stable if it does not change
easily when disturbed
 “Change” = 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

27. 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
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