Name: ______Date: ______Period______

MODELING NATURAL SELECTION - EVODOTS

In Darwin’s model of how organisms change over time, he proposed natural selection as the mechanism of evolution. Evolution takes a LONG, LONG, time. However, we can model years of natural selection in on the computer by modeling just one of the many types of selective pressures. In this case, predation is the selective pressure that you will model. Predation is important to evolution because it places a limit on one of the key requirements of natural selection – the ability of organisms to survive long enough to reproduce.

In this activity you will model the effects of predation on a prey population. We will be using a computer model. The different colored dots will represent a variation in a species. You will act as a predator by clicking on and “eating” the dots.

BASIC DIRECTIONS
HOW TO LAUNCH THE PROGRAM / STEPS TO RUN EVODOTS
  1. Log in to computer
  2. Go to Google and enter “Evodots”
  3. Click on the Jon C. Herron Software site.
  4. Scroll down to “Download Evodots 1.1” and click on “Uncompressed Windows Application”
  5. Click on the Open button, which will launch the program
Click on the introduction screen to make it disappear. Now you are ready to use the program. / 1. Make sure all of the boxes in the bottom right corner are checked
2. Click on New Population
3. Click on Run
4. Kill 25 dots as fast as you can
5. Click on Stop
6. Click on Reproduce
7. Record Data
8. Repeat steps 3-7 until you have finished 5 generations.

Experiment 1: Natural selection on dots relative to their speed

  1. Before you begin, generate a hypothesis about what you will expect will happen over many generations. – Do you expect to see an increase, decrease, or no change in the number of fast dots over many generations of selections. Remember to use If ______then______because formats.

______

2. Click on new population. You will see 50 dots in a variation of colors. These colors represent different speeds. If you click the little arrow in the top right hand corner, it will show you how many of each color you have. Record in the data table.

Dots vary in: / Slowest ------ Fastest
Black / Purple / Blue / Green / Yellow / Orange / Red
Start round 1
Start round 2
After reproduce
Start round 3
After reproduce
Start Round 4
After Reproduce
Start Round 5
After Reproduce
  1. Click “Run” and complete simulation for a total of 5 generations (kill 25 per round, then click reproduce). Record your data in your data table.
  1. At the end of 5 generations describe your results. Which, if any, of the dots had a better survival rate than other dots in the 2nd-, 3rd-, and 4th-genration starting populations? Did these differences support your hypothesis? Has evolution occurred in your dots population? How do you know?

______

  1. Think of and describe a real-life predator/prey relationship that this experiment might be simulating.______

Experiment 2: Evolution relative to dot size OR dot visibility

Go to File/options at the top left of the program. Pick either dot size or visibility. This will change the trait that is variable for your dots. Fill in the data table with your starting population, make sure to indicate whether you or using dot size or visibility.

  1. Before you begin, generate a hypothesis about what you will expect will happen over many generations. – Do you expect to see an increase, decrease, or no change in the number of a certain kind of dots over many generations of selection. Remember to use If ______then______because formats.

______

Dots vary in:
Black / Purple / Blue / Green / Yellow / Orange / Red
Start round 1
Start round 2
After reproduce
Start round 3
After reproduce
Start Round 4
After Reproduce
Start Round 5
After Reproduce
  1. Click “Run” and complete simulation for a total of 5 generations (kill 25 per round, then reproduce). Record your data in your data table.
  1. At the end of 5 generations describe your results. Which, if any, of the dots had a better survival rate than other dots in the 2nd-, 3rd-, and 4th-genration starting populations? Were there differences in the frequencies of dots over 5 generations? Did these differences support your hypothesis? Has evolution occurred in your dots population? How do you know?

______

  1. Think of and describe a real-life predator/prey relationship that this experiment might be simulating. ______

Experiment 3: Testing Needed Evolutionary Conditions

  1. At the start of the experiment we made sure the three boxes “variable” “heritable” and “selective” were checked. In this experiment you will uncheck one of the boxes (click on one the check marks to see it removed).

Which box did you deselect? ______

  1. How do you think this box being deselected will affect the results of your experiment? ______
  2. Run your experiment for 5 generations of selection. Fill in the data table.

Dots vary in:
Black / Purple / Blue / Green / Yellow / Orange / Red
Start round 1
Start round 2
After reproduce
Start round 3
After reproduce
Start Round 4
After Reproduce
Start Round 5
After Reproduce
  1. At the end of 5 generations describe your results. Which, if any, of the dots had a better survival rate than other dots in the 2nd-, 3rd-, and 4th-genration starting populations? Did these differences support your hypothesis? Has evolution occurred in your dots population? How do you know?

______