Name Date Block. 3. Color the corresponding bones of the five other organisms, the same colors you used to model arm and hand bones for the human.

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1 Name Date Block EVOLUTION Anatomical Evidence for Evolution In our upcoming study of anatomy and development of organisms, we will discover that many living things that look quite different on the surface, have similar internal structures that suggest they are related to each other. This is another form of evidence that scientists use to prove that organisms evolve, or gradually change over time. This investigation will allow you to examine homologous, analogous, and vestigial structures, and how each type of anatomical structure plays a valued role in the collection of evidence for evolutionary change amongst organisms. HOMOLOGOUS STRUCTURES Body structures that are formed in similar ways during the development of different types of organisms and that share similar patterns of bone structure, even though they take on different forms and perform somewhat different functions. (Homo- means the same, and logous means information; the root meanings help us translate homologous as the same information ) Activity 1: Forelimb Bone Examination 1. Carefully examine the drawings of forelimb bones from the skeleton of the six organisms in Figure 1, on the next page. Look for similarities in the bones amongst the various organisms. 2. Beginning with the human arm, color the bones of the arm, (humerus, ulna, and radius) using blue colored pencil. Then color the bones of the hand, (carpal, metacarpals, and phalanges), using yellow colored pencil. 3. Color the corresponding bones of the five other organisms, the same colors you used to model arm and hand bones for the human. 4. Observe each of the six skeletons, again, and describe the function of each limb in the table below. Also state one fact/observation that you used to help you determine the function of each limb. Table 1: Forelimb Functions of Six Different Animals Animal Function of Forelimb/Observation(s) that Support Reasoning Human Homo sapien Cat (Domestic Cat) Felis catus Whale (Humpback) Megaptera novaeangliae Bat (Little Brown Bat) Myotis lucifugus Bird (House Finch) Haemorhous mexicanus Crocodile (American Crocodile) Crocodylus acutus

2 Figure 1: Forelimb Bones of Six Different Animals

3 SUMMARY QUESTIONS: HOMOLOGOUS STRUCTURES 1. Are the functions of the limbs of each animal noted in Figure 1, the same or different? 2. Are the bones of the limbs, from the six animals, arranged in a similar way, or were they arranged differently in each animal? Explain your answer using evidence from the bone arrangements in Figure What does the bone structure suggest about a common ancestry amongst these organisms? 4. What possible reasons can explain how the forelimb skeletons of these animals can be similar in structure, but the functions that they carry out can be so different? ANALOGOUS STRUCTURES Body structures that are very similar in function and seem like they are similar in function, but really develop very differently and have different internal structures as a result of developing very differently in early stages of life. (Ana- means against, and logous means information; the root meanings help us translate analogous as against information ) Activity 2: Wing Comparisons 1. Examine the butterfly wing and the bird wing, in Figure 2, located on the next page. 2. Fill in Table 2, using your observations of the wings in Figure 2, focusing on the SIMILARITES, between the Butterly and the Bird. 3. Fill in Table 2, using your observations of the wings in Figure 2, focusing on the DIFFERENCES, between the Butterly and the Bird.

4 Figure 2: Butterfly Wing Bone Structure and Bird Wing Bone Structure Table 2: Wing Comparisons of a Butterfly to a House Finch Animal Similarities Amongst Wings Differences Between Wings Monarch Butterfly Danaus plexippus House Finch Haemorhous mexicanus SUMMARY QUESTIONS: ANALOGOUS STRUCTURES 1. What functions do the butterfly wing and the bird wing share? 2. In what ways are the butterfly wing and the bird wing different? 3. Explain why the butterfly wing and the bird wing are considered analogous structures.

5 VESTIGIAL STRUCTURES Body structures that have been reduced or lost as changes occur over time, as a result of organisms not needing to perform the functions related to that structure (Wings of penguins and leg bones of snakes would be examples of this phenomenon) Activity 3: Comparing Habitats 1. Examine the bodies of the Cavefish and the Minnow in Figure 3, below. 2. Use a TigerBook in the classroom to identify the type of habitat you will find each of the organisms noted in Figure 3. (Please note the websites you used to find your information) Table 3: Habitats of the Minnow and the Cavefish Animal Habitat/Description Common Minnow Phoxinus phoxinus Alabama Cavefish Speoplatyrhinus poulsoni Sources: Figure 3: Bodies of a Minnow and a Cavefish Minnow Cavefish

6 SUMMARY QUESTIONS: VESTIGIAL STRUCTURES 1. Is eyesight an important adaptation to life in a deep sea cave? Explain why or why not. 2. Does the appearance of the Cavefish compared to the Minnow, suggest a common ancestry? Explain your answer. 3. Below is a list of human vestigial structures. Suggest a possible function for each structure and then note a reason why it is considered vestigial. Structure Probable Function Vestigial Because. Appendix Coccyx (tail bone) Muscle that moves ears Muscles that make hair stand up Little toe Wisdom teeth SUMMARY QUESTIONS: VESTIGIAL STRUCTURES