Punch Bug Lab

Integrated Science 2Name:Period:

Background

W

e have discussed, in many contexts, the results of evolution. An excellent example of the results of evolution is the development of camouflage and other protective coloration patterns in a wide range of living organisms. In this lab activity, we will examine the processes that produce protective coloration. Students should be able to draw connections between the development of protective coloration in a given population and natural selection as an evolutionary process. In this simulation, lab groups will trace the number of individuals in a population of different colored punch bugs. The data will be collected over four generations. Each generation will be subjected to a form of evolutionary pressure called predation: the act of one organismhunting another to achieve nutrition!

Focus Questions

•How do species change/evolve over time?

•What are the important steps in the process of natural selection?

•How do species develop protective coloration

Procedures

  1. Working in table groups, unpack and inventory your lab kit.
  2. Unfold your “environment” on the top of your lab-bench.
  3. Record the 6 punch bug variations (colors) in your population in Data Tables 1-4.
  1. Create a starting population of punch bugs that includes 10 individuals of each color in your lab kit. Mix the members of the starting population into a single pile.
  1. One member of the lab group takes responsibility for distribution of the starting population. While the other members of the group look away, that group member randomly scatters the starting population over the entire environment.
    *lab group members take turns acting as the distributor and as the predator
    * group members not acting as the predator take responsibility for counting the eaten bugs
  1. FIRST PREDATION: The first predator will prey upon the punch bugs one at a time while standing over the environment, feeding themselves as quickly as possible until 30 punch bugs have been “eaten” (removed from the environment AS FAST AS POSSIBLE).
     Record the number of each color eaten, and the number of survivors, in Data Table 1. Dead bugs should be returned to the proper stock bottles.
  1. FIRST REPRODUCTION: All of the bugs left after the first act of predation reproduce. Gather the second generation from your stock bottles: one bug of the same color for each bug who survived. Distribute the second generation the same way you distributed the original population.
     Record the new starting population in Data Table 2.
  1. SECOND PREDATION: Follow the same procedures from the first predation. Remember to switch predators.
     Record the number of each color eaten, and the number of survivors, in Data Table 2.
  1. SECOND REPRODUCTION: All of the bugs left after the second act of predation reproduce. Follow the procedures from the first reproduction. Distribute the third generation. Remember to switch distributors.
     Record the new starting population in Data Table 3.
  1. THIRD PREDATION AND REPRODUCTION: Continue the simulation through 1 more generation. Procedures for collecting and recording data remain the same.
  1. FINAL POPULATION: The surviving bugs after the third predation are assumed to reproduce in the same way the previous generations did.
     Based on the population that remains in the environment after the third predation, and their offspring, record the final population in Data Table 4.

Data Tables

Data Table 1: First GenerationData Table 2: Second Generation

Color / Starting Pop. / Eaten / Surviving Pop. / Color / Starting Pop. / #Eaten / Surviving Pop.

Data Table 3: Third GenerationData Table 4: Final Population

Color / Starting Pop. / #Eaten / Surviving Pop. / Color / Final Population
(Surviving Population from 3rd Generation Reproduces to create the Final Pop)

Graph

Use the Final Population data to create a graph below. Properly label all axes and title your graph. Use the graph to answer related questions in the discussion and conclusion section.

Discussion and Conclusion

  1. What were the dominant colors in your cloth?
  2. Which two colors of punch bugs had the highest number of survivors?
  3. Which two colors of punch bugs had the lowest number of survivors?
  4. Explain the relationship between the color of an organism and its environment coloration as it relates to survival of individual organisms.
  5. Consider the punch bugs as living organisms. Did the population adapt to their environment over time? Explain your answer.
  6. Assuming all punch bugs are of the same species, explain why there were 6 different colors in the starting population of this simulation.
  7. Describe the variation in punch bug colors you would have expected after ten generations. Use your data, and colors as an example.
  8. Which punch bug population would be more likely to survive a significant environmental change (for example, a new cloth): the starting population or the population after 10 generations? Explain.
  9. Consider the red finches that you observe in your backyard. They are not camouflaged to their environment. How is this red coloring beneficial?

Identify two additional organisms that benefit from not being camouflaged______

  1. Summarize the relationship between natural selection and evolution as illustrated in today’s activity?

Further Study

You have all learned about several environmental and human factors that can control the rate of evolution or predation of a species. Think of a realistic experiment you could conduct that would test a theory you have about evolutionary or predatory rates. Be specific both about the factor and the organism. Below are some examples.

Human FactorExample: What is the effect of the burning of coal on the evolution of the

monarch butterfly.

Environmental Example: What is the effect of drought on the body size of Galapagos finches?

Design Outline Worksheet

Title/Purpose:

Hypothesis:

Independent Variable (I.V.):

Continuous ____ Discontinuous ____

Levels of I.V.
(2 or more plus the control - which
must be identified)
Number of trials you will
conduct for each I.V. level

Dependent Variable:

Qualitative

Quantitative:

Constants:

Data Table

Construct a blank data table that could be used to collect data for this experiment. Refer your binder for guidelines on how to construct a good data table.

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Punch Bug Lab