Download Answer Questions on a Separate sheet of paper EVODOTS

Answer Questions on a Separate sheet of paper
EVODOTS
Background
For evolution by natural selection to occur, three basic conditions must be met.
1. The first is that you have a big, diverse population. In this population, different organisms have different
characteristics that might help them survive. These are called adaptations.
2. The second condition is that more organisms must be born than can survive. The factors that cause them
not to survive. The factors that cause them not to survive are called selection pressures. Some examples of
selection pressures are disease, predators, and lack of food. If an organisms has an adaptation that makes it
somewhat resistant to disease, better able to get away from predators, or reproduce. Due to heredity, the
offspring have a chance to inherit some of those same adaptations that allowed the parent to survive and
reproduce.
3. The third condition necessary for evolution is time. Many generations need to be born, compete and
reproduce to see a change in an entire species, or to have a new species form.
Pre-lab Questions
1. What are the three conditions necessary for evolution to occur?
2. This computer simulation will look at predations as a selection factor. What are two other selection factors
mentioned in the background.
3. What is an adaptation? Give at least 2 examples.
4. Why do you need a lot of time to see a change in a species?
Procedure
In the Evodots, you will be a predator on the dots. You will eat the dots by chasing them and clicking on them with the
mouse. Now click on New Populations, and then the RUN button and try to kill a few dots. To play your role correctly,
you must act like a hungry predator. Don’t just wait for the dots to come to you. Go after them! Hunt for 1 minute.
When you click the RUN button, the dots stop moving and the wite area on the lower right displays a histogram showing
the distribution of colors among the survivors.
1. Which dots are easier to catch?
2. Why?
Now click the reproduce button. Each of the survivor dots splits in to two cells.
3. Make a hypothesis. If you hunt for several generations, how will the population change?
Now test your hypothesis by hunting for several generations. Click on the Run button again and hunt for 30 more
seconds. Repeat this four times. Look at the bar graphs on the right hand side of your EvoDots screen. The top graph
shows the relative abundance of the colors in the starting population, while the bottom graph shows the relative
abundance of the colors in the current population.
5. Has the distribution of colors changed? How?
6. Which traits was selected for (increased the population – don’t tell me a color! It is not the color that
determines how hard it is to hunt these critters. What makes it hard to catch some of them)?
7. Which traits was selected against (decreased the population)?
In the bottom right hand corner of the EvoDots screen there are options for the dots. Unselect variable. Click on the
population and observe.
8. What do the dots look like?
9. Make a hypothesis. Will evolution occur in this population?
Now test your hypothesis by hunting for several generations. Click on the Run button again and hunt for 30 more
seconds. Repeat this four times.
10. Is there a difference in the beginning and end populations?
11. Has evolution occurred? Why or why not.
Reselect variable in the right hand corner. Unselect selective. Click on New Population, then RUN, and start hunting for
four generations.
12. What do you notice?
13. Compare the two bar graphs. Did the populations change? Why or why not?
Now select selective again. Unselect heritable. Hunt for 1 minute and click to reproduce.
14. What is your observation?
15. Make a hypothesis. Do you expect evolution to happen?
Now test your hypothesis by hunting for several generations. Click on the Run button again and hunt for 30 more
seconds. Repeat this four times.
16. Did evolution occur?
In the top left hand corner of the screen, click on File  Options  Visibility  Okay. Click on New Population  Run 
hunt for 30 seconds and stop.
17. Which dots are easier to catch and why?
18. What is an adaptation that some dots have that allows them to survive and reproduce?
19. Make a hypothesis: if you hunt for several generations, how will the population change?
Now test your hypothesis by hunting for several generations. Click on the Run button again and hunt for 30 more
seconds. Repeat this four times.
20. Did evolution occur?
21. What was the adaptation that allowed the dots to escape their predator?
In the top left hand corner of the screen, click on File  Options  Size  Okay. Click on New Population  Run 
hunt for 30 seconds and stop.
22. Which dots are easier to catch and why?
23. What is an adaptation that some dots have that allows them to survive and reproduce?
24. Make a hypothesis: if you hunt for several generations, how will the population change?
Now test your hypothesis by hunting for several generations. Click on the Run button again and hunt for 30 more
seconds. Repeat this four times.
25. Did evolution occur?
26. What was the adaptation that allowed the dots to escape their predator?
To see the role of mutation in evolution, go to the Window menu in EVODOTS and select Mutations’ Role. Set the
Starting pop’n size to 50. Click on the new population button.
Go through a few rounds of selection and reproduction. Try to make the population evolve towards small dots as quickly
as you can.
27. Is there a limit to how far you can drive the population? Why?
Now note the label at the lower right that says “Size of dots is variable and heritable”. Click on the box next to the label
“with mutation”. The box should now be checked. Make a new population and go through a few rounds of selection and
reproduction. After each round of reproduction examine the dots carefully. Can you spot the mutants? Try again to
make the population evolve towards small dots.
28. After they were born, did the individual dots ever change their size or color? If the individuals didn’t change,
how was it possible for the population to change?
29. Did new sizes appear in the population because the dots needed them in order to survive? If not, where did the
new sizes come from?
30. What role did the predators play in causing the population of dots to evolve? Did they create a need for the
dots to change? Or did they simply determine which dots survived to reproduce and which didn’t?