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NS 1021A: Introduction to Biology: Organisms and the Environment
In this activity, you will be carrying out a simulation that shows how
evolutionary change might occur. Assume you are a mussel on a beach. What are some ways you might be
killed?
Evolution can be a difficult subject to study in real time. Evolutionary
change generally occurs at extremely slow rates. This simulation is
designed to speed up the process, so we can get a glimpse of the process in a
shorter time frame. Set in a rocky coastline habitat, student teams will
carry out two variations of this simulation: the oystercatcher and the driftwood
log. In the oystercatcher simulation, a predator (the
oystercatcher) will visually "hunt" and "kill" their prey "mussels" in the
coastline habitat. In the driftwood log simulations, mussels will
be "killed" by a driftwood log smashing into the coastline habitat. Data
on the mussels will be collected for both variations of the simulation.
After performing the simulations, you will graph your data and share your team's
data with the entire class. We will then compare the two simulations and
discuss types of evolutionary change. What is going to
happen to each of the four mussel sub-populations after running the
oystercatcher and log simulations?
Hypotheses and Predictions
Oystercatcher
Driftwood Log Opening discussion
question:
Introduction:
Materials:
Investigative
Question:
1. Working in pairs, collect the materials and spread out the fabric.
2. Identify Roles: Oystercatcher hunts the mussels. Habitat Manager manages the fabric and bead counts.
3. The Habitat Manager sprinkles the 40 beads onto the fabric and spreads them evenly.
4. The oystercatcher will pick out 30 beads in a predatory manner - look at the fabric and “hunt” the beads that stand out. Do this by picking the beads up one at a time, looking away between each “hunt”.
5. Put the bead victims in the “temporary graveyard” dish, counting them carefully as they are hunted until 30 are removed from the fabric.
6. Stop hunting when 10 survivors are left on the fabric.
7. Remove the remaining 10 bead survivors from the fabric and count them. Write down each color bead and its number remaining in the data sheet provided. Set the survivors aside temporarily in the “survivor” dish.
8. Now multiply the number of each survivor color by 3 and put those numbers in the data sheet. The 4 totals should add up to 40.
9. Count out the correct number of each color in the additions column and add those beads to the 10 survivor beads for the next round and put them all back on the fabric. Make sure you have 40 beads on the fabric for the next round – the 10 survivors plus 30 newcomers.
10. Scatter the 40 beads once more on the fabric.
11. Repeat steps 4-10 two more times, recording the data, for a total of 3 rounds.
Log Simulation
1. Working in pairs, collect the materials and spread out the fabric.
2. Identify Roles: Driftwood Log that “crashes” onto the fabric. Habitat Manager that manages the fabric and bead counts.
3. The Habitat Manager sprinkles the 40 beads onto the fabric and spreads them evenly.
4. With eyes closed, the driftwood log will gently roll or drop the taped pencil randomly into the “habitat” and remove the attached beads. Be sure to watch out for escapees that get knocked off of the fabric!! Put them back on the fabric!
5. Put the bead victims in the “temporary graveyard” dish, counting the dead ones carefully as they are hunted until 30 are removed. It is possible that it will take a few rolls of the pencil at the end to achieve the precise number of 30 beads.
6. Check to make sure 10 survivors are left in the habitat.
7. Remove the remaining 10 bead survivors from the fabric and count them. Write down each color bead and its number remaining in the data sheet provided. Set the survivors aside temporarily in the “survivor” dish.
8. Now multiply the number of each survivor color by 3 and put those numbers in the data sheet. The 4 totals should add up to 30.
9. Count out the correct number of each color in the additions column and add those beads to the 10 survivor beads for the next round and put them all back on the fabric. Make sure you have 40 beads on the fabric for the next round – the 10 survivors plus 30 newcomers.
10. Scatter the 40 beads once more on the fabric.
11. Repeat steps 4-10 two more times, recording the data each time, for a total of 3 rounds.
1. Compare and contrast the oystercatcher graphs.
a. How are the oystercatcher graphs similar?
b. How are the oystercatcher graphs different?
2. Compare and contrast the log graphs.
a. How are the log graphs similar?
b. How are the log graphs different?
3. Compare and contrast the graphs of the driftwood logs vs. the oystercatchers.
4. The Simulation: What do each of the simulation components represent in nature?
5. Were there any other variables that affected how the simulation played out? Do these same variables exist in nature?
6. The Oystercatcher simulation was designed to represent the process in nature called __________________. The driftwood log simulation was designed to represent the process in nature called _________________
7. What if the numbers of each mussel subpopulation were much larger, like in the thousands or even millions - How would this affect the simulation?
8. What if the two mechanisms, logs and oystercatchers, were both operating in the same simulation? Predict the outcome.
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