1. Survival of The Sweetest
The impact of natural selection and the effects of a predator on the diversity of a community.

2. Essential Questions/Objectives
Why is biodiversity important in an ecosytem?
How does predator/prey relationships affect an ecosystem?
How do populations compete for biotic and abiotic factors in the environment?

3. Reading the Introduction (Background information)
Marking the Text:
Number the paragraphs.
Circle unfamiliar words (science or not)
Underline (or highlight) key terms and concepts.
Make notes in the margins

4. 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. Orange and yellow beads will represent the variation found in this species of mussel.

5. 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

6. 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 on your lab sheet.
Yellow = Thin Shell
Favorite!
Orange = Thick Shell
2nd Favorite!

7. Before going to lab station…
Take lab sheet and pencil with you.
Read the instructions on the tables BEFORE beginning.
One person tell Mrs. Chisholm your lab table’s data for class average.

8. Graphing and Analyzing the Data

9. Graphing and Analyzing the Data
On the Right side of your journal

10. 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?

11. 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.

12. 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.

13. Carrying Capacity
the maximum population of a given species that can survive indefinitely in a given environment
Depends on the conditions and resources available
Ex: how many sheep can live on 1 acre of land before the grass doesn’t grow back anymore? Without grass, will the sheep live and be able to reproduce?

14. Biodiversity
the variety of life in the world or in a particular habitat or ecosystem

15. Create a marine food web (on your lab sheet)
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, and Herbivorous Snail eat phytoplankton (tiny marine plants)
*Remember to point your arrows in the direction of energy flow from organism to organism.

16. 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.)

17. Part 2- Going to Tables
Video:
Read the instruction carefully and pay attention to the rules!

18. Part 2- Graph

19. LENSES Graph analysis

20. 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?