Materials Included In Kit

Additional Materials Required

Prelab Preparation

Part 3. Engineering Design for Fitness
Students can prepare the meter sticks and protractors if time is available. 

1. Depending on materials available, set up as many water stations as possible for testing speed. Fill the containers (aquariums or clear plastic totes) about half full of water.
2. On a meter stick, mark a starting point 8 cm from the left edge of the container with a sticky note.
3. On the same meter stick, mark a finishing point 8 cm before the right edge of the container with a sticky note.
4. Place the meter stick across the top of the container (see Figure 4 in the Procedure section).
5. With permanent marker, draw a starting line and finishing line on the face of the aquarium to aid in start/stop accuracy. The starting line should line up with the starting mark on the meter stick, 8 cm from the side. The finish line should line up with the finish line on the meter stick, 8 cm from the side (see Figure 4 in the Procedure section).
6. Prepare the protractors for the students by marking (with permanent marker or sticky note) 5° on either side of 90° to show the maximum deflection allowed.
7. Divide the clay into 15.0 g samples. Each individual should receive a piece of clay to create the fish design. Students work in pairs to assist each other with timing, record keeping and brainstorming. However, each student is responsible for independent data.

Safety Precautions

Remind students to wash their hands thoroughly with soap and water before leaving the laboratory.

Lab Hints

• Enough materials are provided in this kit for 30 students working in pairs. By doing the simulation in pairs, students can engage in a rich discussion. Enough clay is provided for each student to make an individual fish body design.
• This module can reasonably be completed in four, 50-minute class periods. Complete the POGIL^® activity on day one, the demonstration on day two, the engineering design on day three and the final analysis on day four.
• Part 1 is a POGIL activity is designed to be completed in class using the POGIL teaching method. This includes students working in groups with assigned roles to construct their own learning using modeling. For more information, visit www.pogil.org. 
• During the simulation in Part 2, encourage students to compare and discuss their results to see the difference between groups with more antibiotics and those with less. Encourage students to extend beyond the activity and think about selection in nature and how the antibiotics play the role of an environmental change and change the requirements for fitness. Before moving on to the next activity, conduct a class discussion reinforcing the role of environment in fitness and selection.
• During Part 2, stress to students the importance of recording the number of each bacterial type on Table 1 before adding one more bingo chip of each type present, as instructed in Step 4. If the population grows before the data is recorded, students may be confused by the results.
• During Part 3, you will need to set the length of the fishing line as a constant variable based on the container used. Ideally the fish should hang in the middle of the water. Students may attach the fishing line in any manner. Through sample trials, a successful method was to bore a hole using a paper clip through the model fish and thread the line through the center of the model.
• Prior to testing, instruct students to manipulate the model so that it hangs from the fishing line horizontal to the ground.
• If the container is large enough, two tests may occur simultaneously. For example, the width of a 29-gallon aquarium is 31 cm. Two meter sticks can be placed on top allowing two groups to test at the same time.
• Depending on the container used, speeds may not vary greatly. Longer containers will result in greater variance in speeds between body forms.

Teacher Tips

• This module can be utilized during an evolution unit to demonstrate fitness and natural selection while incorporating the practice of model design.
• Student should have background information on heritable traits.
• The simulation of antibiotic resistance is a model of how evolution by natural selection may proceed. Discuss this type of model with students and how it is different from the model built in the engineering task.
• Ideally, a streamlined, sleek body shape with a small cross-section (which reduces drag) is the fittest fish body shape.
• A snake-like body shape will appear to be a better forward swimmer. This is due to the artificial force (student) moving the fish. A fish with this body shape, like the moray eel, would need to undulate the body for motion, slowing the speed.
• Possible extensions for this activity can include varying the materials the students are allowed to use to construct their fish models, varying the water type in which the students are testing the model (fresh, brackish, salt), or determining how mass affects the speed—allowing the use of more or less clay.
• The following student laboratory kits can be used to further explore evolution and natural selection:
  • Stick Bug Survival—Super Value Kit (Flinn Catalog No. FB1607)
  • Beaks—Flinn STEM Design Challenge™ (Flinn Catalog No. FB2130)
• This learning module incorporates the following kits:
  • Antibiotic Resistance Simulation—Student Activity Kit (Flinn Catalog No. FB1928)
  • Fish Fitness—Flinn STEM Design Challenge™ (Flinn Catalog No. FB2129)

Answers to Prelab Questions

Part 3. Engineering Design for Fitness

1. Explain how natural selection leads to changes within a species.

   Individuals with inherited traits well-suited to the environment leave more offspring on average than other individuals. Over time there will be more individuals with traits well-suited for the environment and fewer individuals with traits less suited, which could lead to physical changes within the species.

2. Calculate the average speed of a cheetah that chased an impala 260 meters in 9 seconds before it made the kill.

   Speed = distance/time. 260 m/9 s = 28.9 m/s.

3. Predict the body shape that would allow for the fastest fish, which, in this investigation, indicates the highest level of fitness. Explain your prediction.

   Student answers will vary but should lead toward a streamlined body to reduce drag. Also, students should mention the role of fins in providing stability and preventing rolling.

Sample Data

Part 2: Antibiotic Resistance Demonstration

Part 3. Engineering Design for Fitness

Original Fish Design 
Data obtained from a 29-gallon aquarium with dimensions: 76 cm x 31 cm x 47.5 cm. Data for fish design with disk-like, flat body with 1 dorsal fin, 1 anal fin and vertical pectoral fins. Improved Fish Design
Data for fish with streamlined body with 2 dorsal fins, 1 anal fin and vertical pectoral fins.

Answers to Questions

Part 2: Antibiotic Resistance Demonstration 

1. What general pattern was observed regarding the total number of bacteria present initially and the number remaining after eight doses?

   Overall the number of bacteria decreased from the initial count. Some groups may find the bacteria were completely eliminated.

2. Compare the initial and final counts of the least resistant bacteria. Explain any trends that were observed.

   Initially, the least resistant bacteria were the most abundant bacteria found of the three bacteria present. However, the least resistant bacteria were the first to become eliminated by antibiotics as they are not as able to withstand the antibiotic effects as well as the other two bacteria.

3. Name the strain of bacteria that had the highest fitness without the antibiotic and give one piece of evidence to support this.

   The red strain had the highest fitness because it made up the largest part of the population.

4. Name the strain of bacteria that had the highest fitness with the antibiotic and give one piece of evidence to support this.

   The yellow strain of bacteria had the highest fitness in the presence of the antibiotic because it survived the longest.

5. In this simulation, the three different strains had different reactions to the antibiotic treatment. Describe one way that the strains of real bacteria may be different from one another.

   The genomes of the bacteria had to be different for them to react differently to treatment. Bacteria that can survive in the environment of an antibiotic often have a different gene variant that makes the antibiotic ineffective. In some cases, the gene may change the protein for a binding site on the outside of the bacteria, therefore the antibiotic cannot bind to the bacteria and impact its function.

6. In this simulation, the antibiotic changed the environment. Describe one example of an environment that has changed in a way that challenged the survival of a population of organisms.

   Answers will vary. Some examples include slight changes in the pH of the ocean that challenge the survival of coral; deforestation challenges the survival of shade tolerant plants such as ferns; volcanic eruptions cover soil and make it difficult for plant life to reestablish; loss of sea ice impacts polar bear survival. In order to be correct, students should focus on a single example.

Part 3. Engineering Design for Fitness

1. Describe the reasoning behind your original design. What features were included to make it have the fastest speed?

   Accept all reasonable responses. Look for answers that include a streamlined body design to reduce drag as it is being pulled through the water. Students should discuss fins chosen, two dorsal fins to prevent rolling, anal fin used for extra stability, etc.

2. Compare your data with other groups. Based on the data, would evidence support or refute the claim that “Your original fish design displayed high fitness”? Explain the reasoning for your answer.

   Student answers will vary but must include data to support or refute the fitness of their fish design. A streamlined body design should demonstrate the fastest times indicating higher fitness for this challenge.

3. Describe an environment where nature would select for your fish body shape.

   Accept all reasonable responses. Answers may include open oceans with few obstacles allowing for maximum speed to be achieved in pursuit of prey or to escape predators.

4. Describe an environment where nature would select against your fish body shape.

   Accept all reasonable responses. Answers may include coral reefs, heavily vegetated ponds or lakes, and other aquatic environments with obstacles that would require a more flexible body shape to provide maneuverability.

5. Describe changes made to the original design in order to improve the speed of the fish. Using evidence, explain whether you were successful or unsuccessful.

   Accept all reasonable responses. Answers must include data to support whether or not the improved design increased speed.

6. Describe any limitations present in your data (discuss possible sources of error).

   Accept all reasonable responses. Answers include precision of measurement; for example, the starting mechanism is imprecise. Estimating when the fish head crosses the finish line may also influence speed calculations. The line itself increases drag and may not be consistent in each trial. Allowing for 5º deflection of the line adds some variability to the data.

7. List the similarities and differences, focusing on the structures and functions, between a real fish and your model.

   Accept all reasonable responses. Similarities may include functions of the fins providing stability and preventing rolling. Differences may include the movement not coming from undulation of the body or the caudal fin, but rather the student. Another difference would be that in the aquarium, the water is still, and in rivers or the ocean there may be currents affecting movement. Fish skin or scales are designed for ease of movement through water, and the clay may affect the movement. Finally, fish have flexible bodies to assist in movement through the water, the model does not.

Final Analysis

1. Using a claims, evidence and reasoning model, explain how natural selection and artificial selection connect to fitness.
   1. Propose a claim based in scientific understanding.

      Accept all reasonable answers. The claim is a short statement that connects the observed evidence to scientific understanding of a concept. For example: The fish with the lowest profile and smallest pectoral fins had the highest fitness when speed is a characteristic that improves survival and reproduction.

   2. Discuss specific evidence from the engineering design activity.

      Student answers will vary. The evidence must match the observations the student made. For example, if the student claims that the traits that made their fish have high fitness were the size of the fins and the profile, they would present data from their own trials and that of others that had this type of fish.

   3. Discuss the reasoning for the claim based on connections to the POGIL^® activity, the simulation, and the engineering design activity.

      Student answers will vary. This section should include information about researching the types of fish bodies and how they increase fitness depending on environment and niche.

References

“Evolution and Selection.” POGIL^® Activities for High School Biology. Trout, L., Editor; Flinn Scientific: Batavia, IL (2012).

Introduction

Evolution by natural selection is the primary mechanism for adaptive evolution of organisms ranging from single-celled prokaryotes to multicellular organisms. Organisms that have traits that allow them to survive in their environment live longer and reproduce more often, passing those traits to their offspring.

Concepts

• Natural selection
• Fitness
• Artificial selection
• Antibiotic resistance

Background

Part 3. Engineering Design for Fitness 

Fitness is the contribution an individual makes to the gene pool—all the alleles available in a population—compared to the contributions of others. In other words, an individual with high fitness is capable of surviving to reproductive maturity and producing many healthy, fertile offspring that in turn can survive to reproductive maturity. Most falsely assume that fittest means the largest, strongest or fiercest individual; however this is only the case when those traits help in survival and reproduction. A wild rose with an alluring, sweet fragrance attracts more pollinators than a wild rose with a less aromatic scent, thus the former has a higher level of fitness. 

Fitness is achieved through adaptations. Adaptations are inherited characteristics that improve fitness. Through natural selection these adaptations improve an organism’s ability to survive and reproduce in a particular environment. 

Charles Darwin (1809–1882) first presented his idea of natural selection in 1859 when he published On the Origins of Species. Finches that Darwin observed on the Galapagos Islands were similar to a finch from the mainland in many ways, but ultimately belonged to different species. He noticed that the island finches differed from each other as well. He explained that an ancestral finch population migrated to the islands from the mainland and each new population accumulated adaptations suited to the different environments on each island. In the case of the finches, beak shapes adapted to accommodate the most available food source (see Figure 1).

Natural selection acts upon individual finches. Those with inherited characteristics well-suited to the environment had more offspring on average than other individuals. For example, the finches with thick, stout beaks survived at higher rates in environments with seeds as a food source. They produced offspring and passed those characteristics to their offspring. The offspring, in turn did the same, leading to survival of the fittest finch—the finch with the thickest, stoutest, seed-cracking beak. If this finch had migrated to an environment where insects were the primary food source, it would have had low fitness because its beak was not adapted to the new food source.

Just as the finches adapted—and continue to adapt—to food and diverse island life on the Galapagos Islands, fish also adapt to the environmental pressures of aquatic life. The body shape of a fish is related to the niche it fills. For example, fish with a streamlined body shape, like tuna, have adapted to life in the open ocean. They swim long distances in search of food and mates while avoiding predators. They move seamlessly through the water in opposition to friction and drag due to their narrow, forked tails and sleek body shape. Fish that rest on the ocean floor, like the sting ray, typically have flat bodies with eyes on top of their heads allowing them to hunt prey above them. They move by making wave-like motions with their bodies, and are usually camouflaged to blend in with the sandy ocean floor. There are as many fish as there are niches, and therefore many adaptations to exploit those niches.

Experiment Overview

The purpose of this learning module is to facilitate understanding of natural selection, fitness and antibiotic resistance. First, use the Evolution and Selection POGIL^® activity to discover how natural selection works by examining models from the real world. Then participate in a game that models antibiotic resistance and the importance of taking antibiotics. This model demonstrates how changing the environment of the organism changes which individuals survive. Finally, use the engineering design cycle to engineer a fish for optimum speed.

Part 1. Establishing Background Knowledge 
In groups, complete the Evolution and Selection POGIL^® activity. 

Part 2. Antibiotic Resistance Demonstration 
This simulation demonstrates how antibiotics impact the survival of various strands of bacteria when taken as directed or taken less frequently than directed. The antibiotic changes the environment of the bacteria and a classic struggle for existence ensues. 

Part 3. Engineering Design for Fitness 
The purpose of this investigation is to design and mold a clay model of the fish body shape you believe is capable of the fastest speed across an aquarium. Speed is calculated by dividing distance by time. The fish model must have all the given design criteria and deflect no more than 5 degrees from its vertical support as it moves across the aquarium.

Materials

Prelab Questions

Part 3. Engineering Design for Fitness

1. Explain how natural selection leads to changes within a species.
2. Calculate the average speed of a cheetah that chased an impala a total of 260 meters in 9 seconds before it made the kill.
3. Predict the body shape that would allow for the fastest fish, which, in this investigation, indicates the highest level of fitness. Explain your prediction.

Procedure

Part 2. Antibiotic Resistance Demonstration

1. Obtain 20 red bingo chips, 15 blue bingo chips, 15 yellow bingo chips and one die. Place 13 red, 6 blue and 1 yellow bingo chip on the work surface in front of you and your partner. These chips represent harmful bacteria found in a patient’s body before beginning antibiotic treatment. Set aside the remaining bingo chips.
2. It is time to take the first dose of antibiotics. Roll the die and follow the key in Table 1.
   {11408_Procedure_Table_1}
3. Record the number of each remaining type of bacteria in the data table on the Natural Selection Worksheet.
4. Bacteria are constantly reproducing in the host; in this case, the host is the patient’s body. If one or more bacteria of a particular type (color) are still present in the patient’s body after the first dose (step 2), add one chip of that color to the population. Example: If the patient still has blue and red bacteria present, add one blue and one red chip to the population.
5. Repeat steps 2–4 at least eight times (or until all bacteria have been eliminated) to complete the table on the worksheet.
6. Using the data from the table, construct a graph displaying the number of each type of bacteria versus the number of doses. Use different color pencils to plot the following data: total number of bacteria, least resistant bacteria, medium resistant bacteria, and most resistant bacteria. Connect each set of data points by drawing a colored line.
7. Complete the questions on the Natural Selection Worksheet.

Part 3. Engineering Design for Fitness

Part A. Fish Model

1. Using one piece of clay, shape and mold a fish body that will move efficiently through the water.
2. Fish requirements:
   1. All 15 grams of clay must be used in the design.
   2. Fish must have a minimum of one dorsal fin (see Table 2 and Figure 2).
      {11408_Procedure_Table_2}
      {11408_Procedure_Figure_2}
   3. Fish must have two pectoral fins.
   4. Anal fins and pelvic fins are optional.
   5. Caudal fin must be vertical, not horizontal.
   6. Draw the fish design in Part 3 of the Natural Selection Worksheet.

Part B. Fish Attachment

1. Affix a small paper clip through the hole on the straight edge of the protractor as shown in Figure 3. This creates an easy attachment and removal system for the fishing line in order to make adjustments to the design. Tie a knot in the fishing line to create a loop and attach to the paper clip.
   {11408_Procedure_Figure_3}
2. Thread the fishing line through the body of the model fish. Adjust the fishing line so that the fish hangs down 90° from the top of the protractor. Adjust the fishing line on the fish so that the fish hangs parallel (horizontal) to the ground as well.
3. Adjust the length of the fishing line to the predetermined length set by the instructor.

Part C. Testing Fish Models

1. Position the fish in the water so the “head” is at the start mark on the meter stick (see Figure 4).
   {11408_Procedure_Figure_4}
2. Hold the protractor so the straight edge is at the top. Note: The fishing line should be taut and hang straight down, crossing the 90° mark on the protractor.
3. Practice moving the fish through the water at a constant rate so the deflection remains steady.
4. Use the meter stick as a guide to keep the protractor level as the fish is pulled through the water. The fishing line will not hang straight down due to the resistance of the water, causing the fish to lag behind. The faster the fish is pulled, the more the fishing line will deflect. To keep competition fair, adjust the movement to keep the fishing line deflected by 5° or less as marked on the protractor. As the fish is pulled through the water, the deflection mark cannot be passed by the fishing line. If it is, discard that run.
5. After a practice run, return the fish to the start mark of the meter stick.
6. One partner sets the stopwatch.
7. Determine a “go” signal and move the fish from the start mark to the finish mark.
8. Time from the “go” signal until the head of the fish, not the fishing line, reaches the finish mark.
9. Repeat steps 6–8 for three trials.
10. Record the time for each trial on the Natural Selection Worksheet.

Part D. Improved Fish Design

1. After completing the trials with the original fish, calculating the speed and recording observations, make improvements to the original fish design to increase speed/fitness.
2. Follow the same requirements for clay usage, required fins and fishing line length.
3. Practice moving the improved fish design through the water at a constant rate of deflection.
4. Record data on the Natural Selection Worksheet for three trials with the improved fish design.

Student Worksheet PDF

11408_Student1.pdf