Natural Selection Lab

“Natural Selection Lab” Experimental Question: How do populations evolve by natural selection? Hypothesis: Part 1: Cryptic Coloration (Camouflage) Procedure 1. You will be simulating bird foraging for food. Using your beak (forceps) you will catch insects (jelly beans) from the forest floor (box). 2. Fill your tray with the cage litter. 3. Collect five jelly beans of each variety. Due to genetic mutation eight different colorations show up in the insect population. a. SAFETY NOTE: The jelly beans are not fit for consumption. Do not eat them!! 4. Sprinkle the bag of jelly beans around your tray. Mix them into the cage litter to make them harder to find. 5. Take 30 seconds to find as many jelly beans as you can. Two group members should forage at the same time. a. SAFETY NOTE: You may only use your specially designed beak to collect each specimen to eat. You cannot grab a handful of habitat and sort through it for your meal! 6. Record the color (variety) and number of jelly beans in the “breakfast” chart below. 7. Put all collected jelly beans back into the box to simulate moving to a new location. 8. Repeat the procedure for “lunch” and “dinner.” Part 1: Data (Part 1: Cryptic Coloration) Jelly bellicus Color Breakfast Lunch Dinner Total for all Meals Part 1: ANALYSIS & CONCLUSION 1. Which jelly beans were best adapted to this environment? Explain why those Jelly bellicus varieties did so well. 2. Which jelly beans were not adapted to the environment? Explain why those varieties did not do so well. What happened to them? 3. Explain the advantage of cryptic coloration (camouflage). 4. Predict what could happen to the diversity of the Jelly bellicus population over time if the foraging continues for many generations. BE SPECIFIC in your prediction (that is, which genetic traits will be passed on? Which will not survive? Why?). Part 2: Mimicry After eating mainly spotted pink insects, several of the birds became ill. Those that hadn’t eaten these pink spotted varieties felt fine. The spotted pink insects must have been poisonous! It was difficult to determine which red Jelly bellicus had spots, so most of the birds avoided pink Jelly bellicus altogether. The mimic is the nonpoisonous version (pink jelly belly) while the model is the poisonous variety (pink spotted jelly belly) Procedure 1. The pink spotted variety is now poisonous. 2. Place all 40 jelly beans in the tray. 3. Again search for food for 30 seconds 4. Avoid the color that you have chosen as poisonous. If you pick up a “poison” jelly bean, you must stop and skip the rest of the meal. 5. Record the number and type of jelly beans found for the breakfast chart below. 6. Put all 40 jelly beans back in the box to simulate moving to a new location. 7. Repeat the procedures two more times for lunch and dinner. Part 2: Mimicry Data (Part 2: Mimicry) Jelly bellicus Color Breakfast Lunch Dinner Total for all Meals Part 2: Mimicry Analysis and Conclusions 1. 2. 3. 4. Which jelly bean is the “model”? Which is the “mimic”? What advantage does the mimic have? Give a real example of mimicry. How did your foraging strategy change between Part 1 and Part 2? Part 3: Population shift As time went on, the Jelly bellicus population began to evolve. Some of the organisms seemed to thrive and reproduce, while others became scarce, and some disappeared completely. Procedure 1. Place 40 jelly beans in the box. 2. Forage for 30 seconds. 3. Record the number and type of jelly beans consumed in the first generation chart below. 4. DO NOT return the collected jelly beans to the box. Put the collected candies back in the bag. They have been “consumed” and are no longer part of the gene pool. 5. Determine the number and type of survivors left in the box .Generation 1 started with 5 of each type of jelly bean. To find the number of survivors, subtract the number consumed from 5. 6. Assume that the survivors live and reproduce. For each pair of survivors left in the box, add 2 more jelly beans of the same type. If you have an odd number of survivors, round down. Example: 8 survivors = 4 pairs = 8 offspring 7 survivors = 3 pairs = 6 offspring 7. Repeat the procedure two more times to simulate the next 2 generations. To determine the survivors for generations 2 and3, subtract the number of consumed candies from the “new total” in the previous generation. Part 3 Data: Population shift Generation 1 (Part 3: Population Shift) Jelly bellicus Color Number consumed No. of Survivors No. of Offspring New Total (survivors + offspring) Generation 2 (Part 3: Population Shift) Jelly bellicus Color Number consumed No. of Survivors No. of Offspring New Total (survivors + offspring) Generation 3 (Part 3: Population Shift) Jelly bellicus Color Number consumed No. of Survivors No. of Offspring New Total (survivors + offspring) Part 3: Population Shift Analysis & Conclusions 8. Create a line graph for your results from Part 3. Be sure to label the X- and Y-axes and include a Title and Key. Use a different color line for each variety (color) of Jelly bellicus. 9. Did any of the species become extinct (disappear from the box)? If so, which ones? 10. Which population grew the most? Use numbers to support your answer! 11. Was your prediction in Part 1 about the diversity of the Jelly bellicus population correct? If so, why? If not, why not? a. Overall, what has happened to the diversity of the Jelly bellicus population? How might this affect the future of the jelly bean population? BE SPECIFIC in your answer 12. Evolution by natural selection includes all of the concepts below: a. Genetic Variation: Different individuals have different traits. b. Heredity: Traits can be passed on from parent to offspring. c. Competition: There is competition so that some individuals survive and reproduce more than others. d. Mutation: random changes in the gene pool that can result in new traits e. Natural Selection: The individuals that are most adapted to environment are the ones that are most likely to survive, reproduce, and pass on their genes to the next generation. i. Describe an example of variation that you saw in this activity. ii. Describe an example of heredity that you saw in this activity. iii. Describe an example of competition that you saw in this activity. iv. Describe an example of natural selection that you saw in this activity. Part 4: Extension 1. Suppose that spots on a jelly bean represent a recessive trait. If you started with 20 total jelly beans and only 5 of them had spots, how many of the 15 dominant jelly beans would be heterozygous for the trait? How many would be homozygous dominant? Use the Hardy Weinberg formula to calculate the frequency of genotypes in the gene pool. Recall that p2 represents the frequency of the homozygous dominant population, q2 represents the frequency of the homozygous recessive population, and 2 pq represents the frequency of heterozygotes. p+q=1 p2 + 2pq + q2 = 1 2. Suppose that predators avoid the spotted jelly bean so that they grow in numbers and the plain ones begin to die off. The spotted jelly beans now comprise 64% of the total population. How many plain jelly beans would there be if you have a total of 25 organisms? How many of the plain jelly beans would be carriers of the spotted gene?