This activity uses a virtual lab created by HHMI Biointeractive. To complete this activity students will need a computer with an internet connection and headphones to access videos. This worksheet is modified from the student worksheet provided by HHMI. Also, make sure that your browser allows pop-up windows.
Go to: biol.co/stickfish-bg and read the background information about the stickleback fish.
1. Summarize what happened to the fish in Loberg Lake, include an explanation for WHY it happened.
Stickleback Evolution Lab -- Go to: biol.co/stickfish
2. Define "model organism."
3. What is the purpose of the spines?
4. How did ancestral populations of ocean-dwelling fish come to live in freshwater lakes?
5. Watch the video about pelvic reduction in freshwater stickleback. The loss of the pelvic spines is similar to the loss of which body parts in other four-legged vertebrates?
6. Watch the video with evolutionary biology Dr. Michael Bell. Why is the threespine stickleback a model organism for studies in evolution. List at least two reasons.
7. Click on the link at the top of the page to go to the "overview," then click on the interactive fish. Describe the location of the stickleback spine.
8. Watch the video about stickleback fish armor. In addition to the spines, what is another component of the armor of a stickleback fish?
9. What is the difference between a complete pelvis and a reduced pelvis?
10. Start the tutorial by clicking on the tray of fish, practice scoring the fish until you feel you have mastered the technique. Which do you think is the best view (lateral or ventral) for determining the type of pelvis?
11. Click on Experiment 1 and read the objective. Summarize, in your own words, the objective of Experiment 1.
12. Click on the link to the map of Alaska, and then click on the blue pin "A" to see a larger map. You will notice there are many small lakes in this area. One lake you will study is Bear Paw Lake. Name two other lakes in this region.
13. Watch the video of the scenery around Cook Inlet. What other types of animals are present in this environment (as seen on the video)?
14. Click on "Part 1" in the menu at the top and watch the video on how the fish were caught. Describe the method biologists use to trap the fish.
15. Click on "Part 2" in the menu at the top and watch the video on stickleback poulation in Bear Paw and Frog lakes. Describe the major differences between these two lakes.
16. Click to read more about the importance of random sampling. Why are random samples used rather than the entire population?
Give an example of sampling bias.
17. Go to the experiment by clicking on the blue gloves in the lab window. Click on "Skip Part 1: Staining." You will go straight to scoring the fish, just like you did in the tutorial. The program will keep track of your fish scores.
After you have scored all of the Bear Paw Lake fish, indicate the number that were:
Absent _____ Reduced _____ Complete _____
After you have scored all of the Frog Lake fish, indicate the number that were:
Absent _____ Reduced _____ Complete _____
18. Use a bar graph to graph your data. Be sure to label all of your axes.
____1. How did some ancestral sea stickleback populations come to live exclusively in fresh water?
____2. What happened to these fish as they adapted to living exclusively in fresh water?
____3. Why do some stickleback populations lack pelvic spines?
____5. Which of the following is a definition of the process of natural selection?
6. Consider that stickleback evolution has followed similar patterns in other lakes across the globe. Make a prediction about what would happen in an isolated lake with few predators if humans introduced predatory fish like trout. Support your prediction with evidence from the virtual lab.
7. "Selection Strength" refers to the amount of pressure the environment puts on an organism to change. It is measured in the survival rates of those organisms that have (or do not have) a particular trait. The greater the strength of selection, the faster evolution will occur. How could biologists in a controlled environment increase the speed of evolution in the stickleback fish. Explain your answer.