OWL PELLETS



Whale EvolutionIntroductionWhales are mammals. It is thought that they evolved from land mammals that returned to the sea. Today we will look at various types of evidence in support of this theory.Essential Question: What evidence is used to determine the evolutionary history of an organism?MaterialsTimelinesWhale fossil stripsAnkle bone cardsDNA stripsBlue whale modelKiller whale modelsRegister tapeTape measureActivity 2 reading sheet Ankle comparison cardScale the WhaleWhales come in many sizes. The Blue Whale is the largest of all animals, modern or primitive. Compare lengths of various whales and whale relatives in this activity.Measure each whale model in centimeters. Record results in data table 2.Multiply each measurement by model scale to calculate each whale’s actual length. Record results in table 2. (Models range from 16 to 120 times smaller than they appear in real life.)Convert the actual length in cm to meters (table 2).Measure the appropriate length of register tape for each whale. Scale: 1m = 10 cmLabel the register tape with the mammal’s name and length.Fix the tape to the wall for comparison.Scale the WhaleModern WhalesAve. Length Blue whaleModelHumpback whaleModelGray whaleModelSperm whaleModelKiller whaleModelDolphinModel ArchaeocetesAve. length (m)Dorudon4.6mBasilosaurus15.5mRodhocetus2.7mAmbulocetus2.8mPakicetus1.9 mMesonychidsAve length (m)Pachyaena1.7Different types of scientific evidence will be studied to piece together the change in organisms that resulted in the modern whale.Activity 1: Fossil Evidence FolderComplete activity according to instructions on plete the data sheet for activity 1Activity 2: Comparing Homologous structuresRead the information on E5Whale : Activity 2: Comparing Homologous (Vestigal) structuresHomologous structures imply that there may be a common pare the ankle bone cards of primitive whales with other primitive and modern animals. Look for similarities in structure. Arrange the cards into 2 groups based on plete the data sheet for activity 2Activity 3: Molecular (DNA) EvidenceAs the DNA for a particular gene is inherited by new descendent species mutations can occur. Many of these mutations have no significant effect. The more time that has passed, the more mutations will have occurred.Eleven DNA segments from the gene for beta-casein, a milk protein found in all mammals will be compared. The segment is 60 base pairs (bp) long and is presented for 11 species: 3 cetaceans, 7 artiodactyls, and 1 perissodactyl (outgroup).Compare the DNA strip of each mammal to all of the other 10 mammals. Compare each letter (nitrogen base) in the two strips. Count the total number of letter differences in the sequences.Record the total number of differences on activity 3 data table.Repeat for all remaining strips. Answer all questions on the data sheet.Elaborate: Further lines of Scientific Evidence Read the introduction of the article “The Origin of Whales and the Power of Independent Evidence” Answer the questions regarding “What is a whale?” Each group will be assigned one independent line of evidence for the evolution of whales. 4. The group should identify and be able to identify the authors claim, evidence and reasoning. 5. The group will then present an explanation along with an illustration of the evidenceWhale EvolutionName: ________________________Student Data SheetDate:_________________________Scale the WhaleModern WhalesModel Length (cm)Model ScaleActual Length (cm)Actual length (m)Blue Whale1:96Humpback whale1:38Gray whale1:40Sperm whale1:78Killer whale1:40Dolphin1:16Fossilized MammalsArchaeotcetesLength Dorudon111111111111111111111111111111111111114.6 Basilosaurus1111111111111111111111111111111111111115.5 Rodhocetus111111111111111111111111111111111111112.7 Ambulocetus111111111111111111111111111111111111112.8 Pakicetus111111111111111111111111111111111111111.9MesonychidsLength (m) Pachyaena111111111111111111111111111111111111111.7How do modern whales compare in length to Archaeocetes and Mesonychids?Activity 1: Fossil Evidence – What primitive land mammal is the closest relative of the whale?Timeline Summary table: Label all columns with whale featuresFossil AgeScientific NameBody length (cm)Tooth shapeHoovesSkull(cm)Legs(type)Habitat36 mya37 mya46 mya48 mya50 mya55 myaDuring what time period are there gaps in the fossil timeline?Which time gap would contain the transitional fossil from land to sea?List traits predicted in the transitional fossil.Sketch of predicted transitional organism:Which typical whale traits were the earliest to appear?Which whale traits evolved much later?In what age sediments and in what region of the world would you search to get fossils that would provide more evidence on whale origins?How closely did the ambulocetus fossil match the predicated traits?Does ambulocetus seem to fit well into the gap between pakicetus and Rodhocetus?Explain why the absence of intermediate (transitional) fossils is not a good argument against evolution.Activity 2: Homologous structuresDefine the following terms from the reading passage in this activity:Archeocete – Ungulate – Artiodactyl – Mesonychid – Cetacean – Perissodactyl –Homologous structure – Is the ankle bone of the Mesonychid more similar to the bone of the Perissodactyl or an Artiodactyl? Is the ankle bone of early whales (Pakicetus) more like those of Perissodactyl, Mesonychids or an Artiodacty? Based on your answer to question 3, with which group do modern whales most likely share a common ancestor? Scientific evidence previously pointed to the mesonychids as the closest related ungulate of the whale.Does your current evidence agree with previous scientific thought? If not, what does this proposed change in ancestry tell us about the nature of science?Activity 3: Molecular evidence:Complete Data chart with the number of nitrogen base differencesS. WhalePorpoiseGiraffeHippoCowCamelDeerPigPeccaryRhinoR. WhaleS. WhalePorpoiseGiraffeHippoCowCamelDeerPigPeccaryRhino Based on the class data, list all of the pairs of mammals that have fewer than five difference in their DNA sequences: Based on the background reading in the beginning of this activity, what inferences can you make about which animals are more closely related to each other? Which Artiodactyl (even-toes modern Ungulate) has DNA which is clearly most like the Cetaceans (whales, dolphins, and porpoises)? What inferences can be made about which four-legged animals are more closely related to Cetaceans?What is a Whale? List 3 characteristics that identify whales are mammals: 24. List 7 characteristics of whales that are unique to whales and not found in other mammals 25. Complete the following after reading assigned evidence:Claim:EvidenceReasoning: ................
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