Transcript Biodiversity and Ecosystem Stability

Catalyst: August
th
28
, 2014
You need your ActivExpression!
Prepare for our Carrying Capacity
quiz!
Have your DBA #2 on your desk!
Agenda

Catalyst (10 minutes)
Biodiversity and Change PowerPoint (10 minutes)
Biodiversity Whiteboards(15 minutes)

Homework: HP 9/26


Announcements

Biodiversity quiz on Monday
Objectives



SWBAT define biodiversity
SWBAT predict the impact of various environmental changes based on the amount of
biodiversity in an ecosystem
SWBAT establish a relationship between the amount of biodiversity in an ecosystem and the
likelihood of extinction of a species in that ecosystem
SWBAT describe invasive species and their impact on an ecosystem’s biodiversity.
SWBAT define and describe extinction.
SWBAT predict the effects of certain environmental factors on an ecosystem’s biodiversity.
Biodiversity and Change
Biodiversity is…

Biodiversity is a measure of how many different
species live in an ecosystem.
High vs. Low Biodiversity


Ecosystems with high biodiversity have many
different species of organisms.
Ecosystems with low biodiversity do not have many
different species of organisms.
High Biodiversity
Low Biodiversity
Low or High Biodiversity?
Low or High Biodiversity?
Low or High Biodiversity?
Low or High Biodiversity?
Low or High Biodiversity?
Ecosystem Stability

The higher the biodiversity, the more stable
the ecosystem (stable= stays the same)
 An
ecosystem with high biodiversity does not
change easily; it is stable
 An ecosystem with low biodiversity is unstable
 One
small change could cause many species to die
Low Biodiversity
Rabbits eat grass. Foxes eat rabbits
Foxes
Rabbit
Grass
Low Biodiversity
A disturbance hits…
A drought happens and kills all the grass.

Foxes
Rabbit
Grass
Low Biodiversity

What happens to the foxes?
How many species do we have left?
0!
BIG change?
Grass
Rabbit
Foxes
Higher Biodiversity
Let’s add a few more species to our original
ecosystem
Foxes
Lettuce
Rabbit
Chickens
Grass
Higher Biodiversity
A disturbance hits…
A drought happens and kills all the grass.

Foxes
Lettuce
Rabbit
Chickens
Grass
Higher Biodiversity




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 have a major impact!
Foxes
Lettuce
BIG change?
Rabbit
Chickens
Grass
Example: Low vs. High
Ecosystem 1
Ecosystem 2
CFU 1: Which ecosystem has
higher biodiversity?
Ecosystem 1
Ecosystem 2
CFU 2: Which ecosystem would be
more affected by a disease that
killed all the rats?
Ecosystem 1
Ecosystem 2
CFU 3: Which ecosystem is more
stable? Why?
Ecosystem 1
Ecosystem 2
CFU 4: What might happen to the snakes in Ecosystem
2 if there are not any of that species of snakes anywhere
else in the world and most of the rats in the ecosystem
die from disease?
Biodiversity and Extinction

Environmental change in an ecosystem with low
biodiversity can even cause extinction of a species
 Can
occur if there are no organisms of that species in
other ecosystems throughout the world

Species with specialized diets (low surrounding
biodiversity) and specific habitats are more likely
to become extinct than species with diverse diets
and a wide range of habitats
Invasive Species

Invasive species are non-native species of organisms in an
ecosystem that reproduce quickly and have few natural
predators



Invasive species decrease biodiversity in an ecosystem by
taking over food and space from native species


Native= originally from that ecosystem
Non-native= originally from somewhere else
Decrease the number of native species
Invasive species are very harmful to ecosystems that
already have low biodiversity
Invasive Species

Examples:
 Zebra
mussels
 Kudzu plant
 Brown tree snake
 Wild hogs
CFU 5


Brown tree snakes are a species of snakes that
were imported to the island of Guam from South
America. Brown tree snakes eat many different
types of birds and lizards. They reproduce rapidly
and have few natural predators. What will most
likely happen to the number of native bird and
lizard species on Guam over time?
CFU 6

Does an invasive species normally
increase or decrease biodiversity
in an ecosystem?
Zebra Mussel Reading and
Questions

Options for reading:
 Whole
class
 Small groups
 Partners
 Individually
Catalyst: August

th
29 ,
2014
Introduction to ALA ACT method.
Agenda



Catalyst: 10 minutes
Biome Jigsaws: 15 minutes
Biome Presentation: 10 minutes
Announcements


DABA #3 due 9/8
LABOR DAY WEEKEND!!!
Objectives

SWBAT analyze the features of major global
biomes.
Biomes Jigsaws




7 groups
Each group will be assigned a biome reading.
You must identify the following factors for your
biomes:
Presentation: After 15 minutes, each group will
present major features of their assigned biome. The
rest of the class will fill in their graphic organizers
accordingly.