Download Survival of The Sweetest

Survival of The Sweetest
The impact of natural selection and the effects of a predator on
the diversity of a community.
Biodiversity
•The differences in living organisms within an ecosystem.
•The greater the biodiversity,
ecosystem.
the more sustainable the
Limiting Factor
•Any biotic or abiotic factor that restrict the number of
individuals in a population such as competition for food and
space.
Carrying Capacity
•The maximum population
environment can support.
size of a species in which the
Essential Questions/Objectives
• Why is biodiversity important in an ecosystem?
• How does predator/prey relationships affect an
ecosystem?
• How do populations compete for biotic and
abiotic factors in the environment?
Reading the Introduction
(Background information)
• Title page #5 in your
BOSS “Natural
Selection” and take
notes as you read the
background information
on Survival of the
Sweetest.
Create a Circle Map
of Natural Selection
on page #4 in your
BOSS.
Natural
Selection
(Left side of Journal)
Discuss with your group what you read
and create a circle graph in your journal
about Natural Selection. List everything
you know about natural selection.
Be prepare to share.
Part 1- Genetic Variations (same species)
•
In Part I, you will simulate the events of natural
selection for a population of mussels living in the
rocky, intertidal zone of the Pacific Ocean.
•
Mussels are bivalves much like clams and
oysters. This simulated population of mussels
(Peloris dulcis) has individuals with thick, strong
shells and others with thin, weak shells. The
thick shell provides more protection from the
predaceous starfish lurking in the shallows.
•
The starfish more readily eats the mussels with
the thin shells. White and yellow beads will
represent the variation found in this species of
mussel.
Part 1-Genetic Variation (same species)
• Yellow = Thin Shell
• Starfish will eat these first.
• Orange = Thick Shell
• Starfish will eat only if
no yellows are available
Part 1- Genetic Variation (same species)
•
You are the Predatory Starfish!
•
As the predator, you prefer to eat the yellow
mussels with thin shells rather than the
thicker shelled orange ones
•
Formulate a hypothesis regarding what will
happen to the ratio of yellow to orange
mussels knowing the predator’s preference.
•
Record your hypothesis in your BOSS on page
#7.
Yellow = Thin Shell
Favorite!
Orange = Thick Shell
2nd Favorite!
Procedures
• Follow the procedures simulating
predation and reproduction of
your mussels using the template
representing the rocky shoreline.
• Record your data in Table 1.
Class Averages
•As a class, calculate the
class average for each
generation and record
the data in Table 4.
•Glue/Tape both Table 1
and Table 4 onto page #7
of your BOSS.
Graphing and Analyzing the Data
• Title your Graph.
• Label the X and Y axis
• Create a key representing what
line on you graph represents
each color mussel.
• Create a double line graph
representing the class average
data.
CONCLUSION QUESTIONS – All answers must be in
complete sentences.
1.
Which type of mussel would Darwin consider “most fit” in this
predation situation? Why?
2.
What adaptation do these mussels possess that allows them to
survive?
3.
Explain why it is incorrect to say that an individual adapts to its
environment.
4.
Re-examine your hypothesis, was it accepted or rejected? Why?
CONCLUSION QUESTIONS Part I
1.
Which type of mussel would Darwin consider “most fit” in this predation situation?
Why?
•
The thick shelled mussels because they are harder for the starfish to eat.
2.
What adaptation do these mussels possess that allows them to survive?
•
3.
Explain why it is incorrect to say that an individual adapts to its environment.
•
4.
They have the favorable trait of thicker shells.
Individuals don’t adapt, populations of a species adapts over generations by
surviving, reproducing and passing down the favorable genetic traits.
Re-examine your hypothesis, was it accepted or rejected? Why?
•
Our hypothesis was accepted because we said that the thin shelled mussel
population would decrease and the thick shelled mussel population would
increase which our data supports.
Part 2- Community Diversity and Competition
•
In Part II, you will simulate the effects of a
predaceous starfish on the diversity of a
community made up of barnacles, mussels,
chitons, and snails.
•
You will also simulate the effects of
removing the predaceous starfish on the
diversity of the community.
•
In addition, each species is competing for
limited space. Competition can force some
species out of the ecosystem.
Keystone Species
•
Many communities have species with larger than expected
effects on their environment. Biologists refer to these as
keystone species.
•
The keystone species in this model is a large, predatory
starfish. The starfish preys upon all five species. The
carnivorous snail eats both mussels and barnacles. Each
species competes for the limited space along the rocky
shoreline.
Create a marine food web
(in your BOSS)
•
The starfish preys upon all five species.
•
The carnivorous snail eats both mussels
and barnacles.
•
Each species competes for the limited
space along the rocky shoreline.
•
Barnacles, Chitons, Mussels and
Herbivorous Snail eat phytoplankton
(tiny marine plants)
*Remember to point your arrows in the
direction of energy flow from organisms to
organism.
Part 2- Hypothesis
•
After illustrating your marine food web, formulate a
hypothesis predicting the abundance(amount) of the five
prey species if the predatory starfish is removed from the
environment. Record your hypothesis on your lab sheet.
•
Example: If the starfish is removed, then…(this will happen to
the mussels, the barnacles, etc.)
Part 2- Graph
Create a line
graph of the
orange mussel
final population
for each
generation. Be
sure to include
the axes’ labels,
unit and a title
on your graph.
Conclusion Questions
1. Which organism possesses traits that enable it to exploit the rocky
shoreline more efficiently than the other populations in the
community? Explain.
2. Compare the change in the diversity of the community in
Generation 1 to Generation 10. What major factor accounts for this
change?
3. Define biodiversity and explain how it affects an ecosystem. How
did this simulation justify the concept of biodiversity?
4. Re-examine your hypothesis, was it accepted or rejected? Why?
Survival of the Sweetest Conclusion
•Discuss your answers with your group
•Check your answers to the conclusion
questions and make corrections if
needed.
Conclusion Questions
1. Which organism possesses traits that enable it to exploit the rocky
shoreline more efficiently than the other populations in the
community? Explain.

The orange mussels because of their high reproduction rate that
enables them to take over the rocky shoreline.
2. Compare the change in the diversity of the community in
Generation 1 to Generation 10. What major factor accounts for this
change?

The diversity decreases since the starfish is not there to keep
populations from getting too large and crowding out the other
population of organisms.
Conclusion Questions Con’t.
3. Define biodiversity and explain how it affects an ecosystem.
How did this simulation justify the concept of biodiversity?

Biodiversity is the difference in living things within and
ecosystem. In this simulation, biodiversity decreases as the
mussel population increases because they over populate and
push the other organisms off the rocky shoreline. The less
biodiversity, the lower an ecosystems sustainability (ability to
survive).
Conclusion Questions Con’t.
4. Re-examine your hypothesis, was it accepted or rejected?
Why?
My hypothesis
was rejected because I thought that the
Carnivorous Snail population would increase the most and that
the orange mussel population would decrease because the
Carnivorous Snail is a predator to the mussels. However, the
orange mussel population increased the most because they
have a much higher reproductive rate. Their population
doubles every generation. When the starfish was removed,
they were no longer prey to the starfish and the carnivorous
snail is not able to eat that much.