Name:_ _Per: ____ Evidence for Evolution WS Scientists use a variety of techniques to determine if species are closely related or not. All of these techniques provide evidence for evolution. If species are closely related, then they must have come from a common ancestor that evolved over time into two separate species. Today we will be using data to analyze the relationships between different species of whales. 1. Scientists use embryos to study the evolution of organisms. An embryo is an unborn organism in the process of development. This is a picture of a whale embryo at the right. Look at the embryo handout given to you and compare the whale embryo to the embryos of other animals. Which embryo on the handout do you think is most closely related to the whale? 2. Why do you think this animal is most closely related to the whale? 3. Scientists also use vestigial structures to look at how organisms evolved. Vestigial structures are structures that an organism has but that are no longer used. For example, humans have a tailbone but we don’t actually have a tail! This is because we came from a common ancestor a long time ago that had a tail. Over time, our tail got shorter and shorter because we didn’t need it anymore. Look at the picture below of a whale showing vestigial structures (pelvis and femur). Why would a whale have a pelvis (hip bone) and femur (legs) even though it doesn’t walk? 4. Look at the diagram at the right. The common ancestor is the organism at the bottom of the “tree”. Would the common ancestor of all these species have a pelvis and femur? 5. In addition to comparing structures that no longer serve a purpose, scientists compare structures that still serve a purpose for the organism. These structures are called homologous structures. Look at the picture to the right. How are the flipper and the human arm similar? 6. How are the whale flipper and the human arm different? 7. Given what you know about humans and whales, do you think they may have shared a common ancestor a long time ago? Why or why not? 8. Fossils can provide scientists with clues as to how organisms evolved. Look at the fossils below. Place them in order by numbering them to show how whales evolved over time. _____ _________ ____________ ____________ ___________ ____#6_____ 9. Scientists use morphology to look at relationships between species. Morphology is the study of physical structures of organisms (ex: limbs, body parts, shapes). Look at the Whale Species Handout and compare each species to the Sei Whale. Which species do you think is most closely related to the Sei Whale? 10. List at least two pieces of evidence from the pictures that led you to believe that the species you chose in #9 was most closely related to the Sei Whale. 11. Scientists also use DNA sequences to figure out which organisms are most closely related to each other. Compare the B. borealis (sei whale) DNA sequence to the other species of whales. Circle any differences. B. borealis (sei whale) B. bonarensis (mink whale) B. physalus (fin whale) B. brydei (bryde’s whale) AAA AAG AAG AAA CCG CAC CAC CCC TAG TTT TTG TTG GCG GCA GCA GCG TCA TCA TCA TCA CGG CCC CGG CGG TAA ATT TTT ATT TTT ATT TAA ATT CCC CCG CCG CCG 12. Which species of whale seems to be the most closely related to B. borealis (Sei Whale)? 13. Why do you think this whale is most closely related to the B. borealis (Sei whale)? (Hint: how did you use the DNA to figure it out?) 14. Once scientists have determined which species seem most closely related, they create a diagram called a cladogram that shows how the species are related to each other. Which species of whale seems to be the most closely related to B. borealis (Sei Whale)? 15. How did you determine which species was most closely related to B. borealis (Sei Whale)? 16. Does your answer from question #14 match your prediction from your DNA evidence in #12? 17. Look at the cladogram at the right. Which species do you think would be least related to B. borealis (Sei Whale)? RECAP: 18. List five things that you used in this lab to determine how the Sei Whale was related to different species: Embryo Handout Whale Species Handout Minke Whale Size: 18 feet Weight: 12,000 pounds Snout: Sharply pointed Throat Grooves: 50-70 Dorsal Fin size: 21-23 inches Sei Whale Size: 60 feet Weight: 44,000 pounds Snout: Sharply pointed Throat Grooves: 32-60 Dorsal fin size: 12-18 inches Fin Whale Size: 68 feet Weight: 100,000 pounds Snout: Rounded Throat Grooves: 56-100 Dorsal fin size: 11 inches Bryde’s Whale Size: 40-50 feet Weight: 50,000 pounds Snout: Sharply pointed Throat Grooves: 40-50 Dorsal Fin Size: 12-14 inches Name:_ _Per: ____ Evidence for Evolution WS - KEY Scientists use a variety of techniques to determine if species are closely related or not. All of these techniques provide evidence for evolution. If species are closely related, then they must have come from a common ancestor that evolved over time into two separate species. Today we will be using data to analyze the relationships between different species of whales. 1. Scientists use embryos to study the evolution of organisms. An embryo is an unborn organism in the process of development. This is a picture of a whale embryo at the right. Look at the embryo handout given to you and compare the whale embryo to the embryos of other animals. Which embryo on the handout do you think is most closely related to the whale? Pig or Bat 2. Why do you think this animal is most closely related to the whale? The embryo of the pig or bat looks most similar to the embryo of the whale. 3. Scientists also use vestigial structures to look at how organisms evolved. Vestigial structures are structures that an organism has but that are no longer used. For example, humans have a tailbone but we don’t actually have a tail! This is because we came from a common ancestor a long time ago that had a tail. Over time, our tail got shorter and shorter because we didn’t need it anymore. Look at the picture below of a whale showing vestigial structures (pelvis and femur). Why would a whale have a pelvis (hip bone) and femur (legs) even though it doesn’t walk? The whale evolved from a common ancestor that used to have legs and be able to walk. 4. Look at the diagram at the right. The common ancestor is the organism at the bottom of the “tree”. Would the common ancestor of all these species have a pelvis and femur? Yes because it shows the common ancestor with legs so it would be able to walk. 5. In addition to comparing structures that no longer serve a purpose, scientists compare structures that still serve a purpose for the organism. These structures are called homologous structures. Look at the picture to the right. How are the flipper and the human arm similar? They both have five “finger” bones. They both have the same pattern of one big bone, two small bones, and many little bones. 6. How are the whale flipper and the human arm different? The human arm is longer than the whale flipper. The whale flipper has two very long middle finger bones while the human has finger bones that are all roughly the same size. The “arm bone” of the human is longer than that of a whale. 7. Given what you know about humans and whales, do you think they may have shared a common ancestor a long time ago? Why or why not? Yes because they are both mammals and they both have similar bones in the arms and flippers. They also both have pelvic bones. 8. Fossils can provide scientists with clues as to how organisms evolved. Look at the fossils below. Place them in order by numbering them to show how whales evolved over time. ____4_ ____2_____ ___1_________ ______5______ _____3______ ____#6_____ 9. Scientists use morphology to look at relationships between species. Morphology is the study of physical structures of organisms (ex: limbs, body parts, shapes). Look at the Whale Species Handout and compare each species to the Sei Whale. Which species do you think is most closely related to the Sei Whale? Answers will vary here, but as long as students justify their answer, I mark it correct. 10. List at least two pieces of evidence from the pictures that led you to believe that the species you chose in #9 was most closely related to the Sei Whale. Answers will vary. Common answers include: Similar length, similar weight, similar snout, similar dorsal fin, similar throat grooves. 11. Scientists also use DNA sequences to figure out which organisms are most closely related to each other. Compare the B. borealis (sei whale) DNA sequence to the other species of whales. Circle any differences. B. borealis (sei whale) B. bonarensis (mink whale) B. physalus (fin whale) B. brydei (bryde’s whale) AAA AAG AAG AAA CCG CAC CAC CCC TAG TTT TTG TTG GCG GCA GCA GCG TCA TCA TCA TCA CGG CCC CGG CGG TAA ATT TTT ATT TTT ATT TAA ATT CCC CCG CCG CCG 12. Which species of whale seems to be the most closely related to B. borealis (Sei Whale)? B. brydei because it has the fewest DNA differences 13. Why do you think this whale is most closely related to the B. borealis (Sei whale)? (Hint: how did you use the DNA to figure it out?) It has the fewest differences in DNA (or the DNA is most similar to the Sei Whale) 14. Once scientists have determined which species seem most closely related, they create a diagram called a cladogram that shows how the species are related to each other. Which species of whale seems to be the most closely related to B. borealis (Sei Whale)? B. Borealis 15. How did you determine which species was most closely related to B. borealis (Sei Whale)? B. Borealis is closest to the Sei Whale on the cladogram 16. Does your answer from question #14 match your prediction from your DNA evidence in #12? Yes 17. Look at the cladogram at the right. Which species do you think would be least related to B. borealis (Sei Whale)? B. bonaerensis because it is furthest away from B. borealis RECAP: 18. List five things that you used in this lab to determine how the Sei Whale was related to different species: DNA, morphology, fossils, homologous structures, vestigial structures