Station 1: Evidence from Current Examples Go to the website below: http://www.pbs.org/wgbh/evolution/educators/lessons/lesson6/act1.html Watch the video segment called Why does evolution matter now? After watching the video. Answer the following questions: 1. Why is the Russian prison system considered to be "ground zero" in the fight against TB? 2. What is responsible for the evolution of TB strains that are resistant to multiple drugs? 3. How does the misuse of antibiotics affect the evolution of disease-causing bacteria? 4. Why should we care about a resistant strain of TB in Russia? 5. Where else you would expect the problem of antibiotic resistance to exist Page 1 of 8
Station 2: Evidence from Embryology Odyssey of Life, Part I -- The Ultimate Journey Timing is Everything Can you tell a chicken from a fish? How about a human from a pig? Sure you can, you say. Chickens have wings, fish have fins, humans have arms and pigs have hoofs. But what about when they are just starting to form? The drawings below represent three developmental stages of five different animals. They have been all mixed up -- see if you can tell what's what. Procedure 1. See if you can correctly match the embryos with the animals, placing them in order from earliest to latest stages of development. Use the chart below to organize the squares. 2. (On the back) When you are done, write an explanation of why you ordered the drawings the way you did. What are some similarities among the drawings? What are some differences? What, if any, patterns do you see as you go from stage 1 to stage 3? stage 1 fish chick pig calf human stage 2 stage 3 Page 2 of 8
Station 3: Evidence from DNA Amino Acid Sequences and Evolutionary Relationships 1. Read and highlight the information below: Homologous structures those structures believed to have a common origin but not necessarily a common function provide some of the most significant evidence supporting the theory of evolution. For example, the forelimbs of vertebrates often have different functions and outward appearances, yet the underlying similarity of the bones indicates a common origin. Although homologous structures can be used to demonstrate relationships between similar organisms, they are of little value in determining evolutionary relationships among those structures that are dissimilar. Another technique used to determine evolutionary relationships is to study the biochemical similarity of organisms. Though molds, aardvarks, and humans appear to have a little in common physically, a study of their proteins reveals certain similarities. Biologists have perfected techniques for determining the sequence of amino acids in proteins. By comparing the amino acid sequences in homologous proteins of similar organisms and of diverse organisms, evolutionary relationships that might otherwise go unnoticed are revealed. The fewer the differences between the amino acid sequences of two organisms, the closer their relationship. Conversely, the greater the differences, the more distant the relationship. Further, biologists have found that such biochemical evidence compares favorably with other lines of evidence for evolutionary relationships. Comparing Amino Acid Sequences: 2. Examine Figure 1, which compares corresponding portions of hemoglobin molecules in humans and five other vertebrate animals. Hemoglobin, a protein composed of several long chains of amino acids, is the oxygen-carrying molecule in red blood cells. The sequence shown is only a portion of a chain made up of 146 amino acids. The numbers in Figure 1 indicate the position of a particular amino acid in the chain. 3. Use figure 1, to complete the data table Figure 1. Data Table 1. Organisms Human and Chimpanzee Humans and Gorilla Human and Rhesus Monkey Human and Horse Human and Kangaroo # of Amino Acid Differences Positions in which they vary Page 3 of 8
Inferring Evolutionary Relationships from Differences in Amino Acid Sequences Another commonly studied protein is cytochrome c. This protein, consisting of 104 amino acids, is located in the mitochondria of cells. There it functions as a respiratory enzyme. Examine Figure 2 and Figure 3. Using human cytochrome c as a standard, the amino acid differences between humans and a number of other organisms are shown. Use the information presented in the tables to answer the questions that follow. Figure 2. Species Pairing Number of Differences Human - Chimpanzee 0 Human Fruit Fly 29 Human- Horse 12 Human - Pigeon 12 Human Rattlesnake 14 Human Red Bread Mold 48 Human Rhesus Monkey 1 Human Screwworm Fly 27 Human Snapping Turtle 15 Human Tuna 21 Human Wheat 43 Figure 3. Species Pairing Number of Differences Fruit Fly Dogfish Shark 26 Fruit Fly Pigeon 25 Fruit Fly Screwworm Fly 2 Fruit Fly Silkworm Moth 15 Fruit Fly Tobacco Hornworm Moth 14 Fruit Fly Wheat 47 Analysis Questions: Use Figure 1. 1. On the basis of hemoglobin similarity, what organisms appear to be most closely related to humans? Explain. 2. Among the organisms that you compared, which one appears to be the least closely related to humans? Explain. Use Figures 2 and 3. 3. On the basis of differences in their cytochrome c, which organisms appear to be most closely related to humans? Explain 4. Which organisms appear to be least closely related to humans? 5. Check the pair of organisms that appears to be most closely related to each other. snapping turtle tuna snapping turtle rattlesnake snapping turtle pigeon Give a reason for your answer: Page 4 of 8
Station 4: Evidence from Anatomy Homologous Structures Anatomical homology: an example The figure shows the bones in the forelimbs of different organisms (obviously not drawn to the same scale!). Although used for such different functions as throwing, swimming, and flying, the same basic structural plan is evident in them all. Body parts are considered homologous if they have the same basic structure the same relationship to other body parts, and, as it turns out, develop in a similar manner in the embryo. It seems unlikely that a single pattern of bones represents the best possible structure to accomplish the functions to which these forelimbs are put. However, if we interpret the persistence of the basic pattern as evidence of inheritance from a common ancestor, we see that the various modifications are adaptations of the plan to the special needs of the organism. It tells us that evolution is opportunistic, working with materials that have been handed down by inheritance. PART II: ACTIVITY 1) Color the homologous bones according to the color scheme below: Green = humerus Red = radius Blue = ulna Yellow = metacarpals Purple = phlanges 2) Answer the following questions: Do homologous structures have the same function in different organisms? What do homologous structures have in common? How does the existence of homologous structures support the theory of evolution? Page 5 of 8
Code to forelimbs: A: Lemur B: Frog C: Bird D: Whale E: Human F: Cat G: Bat B A C D D D F G E Page 6 of 8
Station 5: Evidence from the fossil record The Fossil Record as Evidence for Evolution ANSWER QUESTIONS 1 AND 2 BEFORE YOU WATCH THE VIDEO Questions: 1. What characteristics do whales have that make them adapted to life in the ocean? 2. What are some animals that you think would share a common ancestor or be closely related to whales? Now watch the video on whale evolution at the link below. You will be asked to list evidence used by scientist to show evolution of the whale so pay attention. http://www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html 3. Revisit question #2. After watching the video, did your answer change? If so how? 4. List three pieces from the video to support your answer. Page 7 of 8
Putting It All Together In the space provided, write one sentence explaining how each of the types of evidence supports the theory of evolution. The fossil record: Anatomy: DNA: Embryology: Current Examples: Page 8 of 8