Evidence from Current Examples



Name: Period:

Date:

Station 1: Evidence from Current Examples

Go to the website below:



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

|Odyssey of Life, Part I -- The Ultimate Journey |[pic| |

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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?

|[pic] |[pic] |[pic] |[pic] |[pic] |[pic] |

| |fish |chick |pig |calf |human |

|stage 1 | | | | | |

| | | | | | |

|stage 2 | | | | | |

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|stage 3 | | | | | |

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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.

|Organisms |# of Amino Acid Differences |Positions in which they vary |

|Human and Chimpanzee | | |

|Humans and | | |

|Gorilla | | |

|Human and | | |

|Rhesus Monkey | | |

|Human and | | |

|Horse | | |

|Human and | | |

|Kangaroo | | |

Data Table 1.

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: ________________________________________________________________

__________________________________________________________________________________________

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

After coloring the diagram on the back of this sheet according to the key 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?

1. Carefully examine the drawings of the bones below.

2. Color the bones of the human arm as follows:

• Humerus – red

• Ulna – yellow

• Radius – orange

• Carpal – green

• Phalanges – blue

3. Color the corresponding bone in each of the other animals the same color as used in the human arm.

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.



Put the whale ancestor fossil diagrams in order from oldest to most recent and describe the changes that have occurred.

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.

If fossils were found in Layer C (sandstone) and Layer

A (slate and siltstone), which fossil would be older and

why?

Station 6: vestigial structures

|A vestigial structure is a feature that was an adaptation for the organism’s ancestor, but that evolved to be non-functional because the organism’s |

|environment changed. |

|Fish species that live in completely dark caves have vestigial, non-functional eyes. When their sighted ancestors ended up living in caves, there |

|was no longer any natural selection that maintained the function of the fishes’ eyes. So, fish with better sight no longer out-competed fish with |

|worse sight. Today, these fish still have eyes—but they are not functional and are not an adaptation; they are just the by-products of the fishes’ |

|evolutionary history. |

[pic] [pic]

Cave Fish Minnow

1. The cave fish lives in an underground cave where there is no light. The minnow lives in a pond where there is light.

2. Why is eyesight not an important adaptation to life in a cave? _________________ ____________________________________________________________________________________________________________________________________

3. Humans have several vestigial structures. Read the article at your station and write the possible functions of the structures below.

|Structure |Possible Function |

|Appendix | |

|Coccyx (tail bones) | |

|Muscles that move ears | |

|Muscles that make hair stand up | |

|Wisdom teeth | |

Do you think these structures are vestigial? Explain your answer.

Analagous structures perform similar functions, but are very different in their structure and form. Analagous structures DO NOT indicate close relatedness between species. And can oftern be the result of convergent evolution, this is where two species that occupy similar roles in their environments and so similar traits arise via natural selection.

1. Examine the butterfly wing and the bird wing shown in the picture below.

2. What function do these structures perform for the butterfly and the bird? _____________

3. What is the butterfly wing made of? ____________________ Does it have bones? _____

4. What is the bird wing made of? ______________________ Does it have bones? ______

|Read the description of the shark and dolphin. What traits do they have in common? |

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|What traits are different? |

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|If they are not closely related why do they look so similar to each other? |

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|How do analogies evolve? |

|You have probably noticed that dolphins and sharks both have a streamlined body shape with a triangular fin on the back and two side fins. However, |

|the two animals also have many differences. |

|Sharks |

|[pic] |

|Dolphins |

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|[pic] |

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|[pic] |

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|skeleton made of cartilage |

|[pic] |

|skeleton made of bone |

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|use gills to get oxygen from the water in which they swim |

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|go to the surface and breathe atmospheric air in through their blowholes |

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|don't nurse their young |

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|do nurse their young |

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|don't have hair |

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|do have hair — they are born with hair around their "noses" |

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|[pic] |

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|[pic] |

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|They may share the same basic shape, but underneath their skins, sharks and dolphins are very different! |

|The following tree shows the relationship between various groups, including cartilaginous fishes (sharks) and mammals (dolphins). They are not very |

|closely related to one another. So how did they end up looking so much alike? |

|[pic] |

|What's the advantage? |

|If two species face a similar problem, challenge or opportunity, evolution may end up shaping them both in similar ways. Both dolphins and sharks swim|

|after prey in the ocean. Streamlined bodies and fins provide a big advantage for them, allowing them to swim faster. We know that dolphins and sharks |

|are not closely related, and they didn't inherit their similar body shapes from a common ancestor. Their streamlined bodies, dorsal fins and flippers |

|are the result of convergent evolution. Since dolphins and sharks occupy similar niches and face similar challenges, similar adaptations have been |

|advantageous to them, resulting in their analogous structures. |



Putting It All Together

In the space provided, write one sentence explaining how each of the types of evidence supports the theory of evolution.

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Station 2: Evidence from Embryology

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Current Examples:

Embryology:

DNA:

Anatomy:

The fossil record:

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