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10/15/12 “Mutations” – INB P. 79 Sponge: The DNA fingerprint for a mouse is ATCGATGCA, an elephant shrew is CGTTAAGCC, and an elephant is CATTAACGG. 1. What would the other rung of the DNA ladder look like for each organism? Mouse-TAGCTACGT, elephant shrew-GCAATTCGG, elephantGTAATTGCC 2. Which two organisms would be the most closely related? Explain. Elephant and the Elephant Shrew because their DNA sequence is more similar than that of the mouse. 10/16/12 “Build a Beast” INB P. 81 Sponge: P. 177: 1. Explain the relationship between an organism's adaptation and evolution. Organisms that have beneficial adaptations survive better than other members of the same species. 2. How is your answer for number one similar to Darwin's theory of Evolution by Means of Natural Selection? It is the same. Darwin says that these organisms survive and are more likely to produce offspring with the same adaptations. 10/19/12 “Natural Selection” INB P. 87 Sponge: P. 177-178: 1. Explain the relationship between mutation and variation and how do these terms influence evolution? Mutations cause variations among offspring that are acted on by natural selection. 2. Explain how species change over time and become better adapted to conditions. Some offspring inherit beneficial mutations that are passed on to their offspring. Natural Selection Mini-Lesson 1. What color is the bark of coniferous trees? Black or dark brown 2. What color is the bark of deciduous trees? Gray or gray brown 3. What biomes are gray squirrels found in? They are found in deciduous and coniferous forest biomes. 4. How does natural selection determine which squirrels survive in which biome? The squirrels that are the most camouflaged for the biome are the ones that survive. Natural Selection Mini-Lesson Cont’d 5. Darwin uses the term “survival of the fittest”. What did he mean by this term? The organisms with the best adaptations for the environment survive and produce offspring. 6. What are the two niches of gray squirrels? Finding food and avoiding predators. 7. How do you think trees benefit from the gray squirrels? Gray squirrels plant trees. 10/17/12 “Bird Beak Adaptations” INB P. 83 Sponge: P. 173: 1. What observations did Darwin make and when did he make them? The diversity of living things, the remains of ancient organisms, and the characteristics of organisms on the Galapagos Islands. 2. How do you think evolution is different from this idea? Evolution is the idea that all living things have changed over time to become better adapted to the environment. Take a few quick notes about evolution: Earth is approximately 4.6 billion years old, and the planet has changed a great deal during its existence. For organisms to survive, they would have to change (mutate) also. A mutation is any permanent change in the DNA of a gene or chromosome. Some mutations are BAD, some can be GOOD and some don’t really have any effect. Examples of mutations: Albinism Other Mutations… Some mutations lead to adaptation… When a mutation is beneficial and helps an organism to survive in its environment, the organism has the opportunity to live a long life, find a mate, and pass on its beneficial traits to its offspring. For example, a zebra’s stripes allow it to confuse predators when traveling in herds. This allows them to survive another day to pass on their traits during reproduction. An adaptation is a characteristic that helps an organism survive and reproduce in its environment. They include structures and behaviors for finding food, a mate, for protection, and for moving from place to place. Charles Darwin Charles Darwin, studied the characteristics of organisms in the Galapagos Islands and noticed that they were similar to those on nearby South America. He hypothesized that animals came to the Galapagos from the mainland. The environment determined which animals would survive and which would die off. Those adapted to the new environment survived and became different from their mainland relatives. Example: Iguanas & Finches Bird Beak Adaptation Activity Pre-lab questions 1. How do birds adapt to their environment? Beaks adapted to food source, special feathers for type of flight, special claws or eyesight for hunting, feather colors, etc. Purpose: How does the shape of a bird’s beak helps decide what it can eat? Hypothesis: Match the “bird beak” on the left with the “food item” it may be best suited for picking up on the right Bird Beak Food Item Tweezers Pasta Spoon Paperclips Fork Marbles 1. 2. 3. 4. 5. 6. Procedure: Select a beak from the objects provided by your teacher Get one plastic cup filled with “food” and empty it out slowly in front of you on a paper plate. There are 20 food items in each cup. The empty cup now represents your “stomach.” One student will hold the beak and one student will hold the stomach. When your teacher tells you, use your beak to pick up the “food” at your lab station and place them in your “stomach” one item at a time. You will have 20 seconds to get as many food items as possible. When your teacher says “Stop,” empty your stomach and count the number of food items that were collected. Record your number in your “Bird beak data table” in your notebook. Swap materials and continue until your table is full What type of bird would have beaks similar to the ones we used in class today? a. b. c. d. e. Nectar sipper (sunbird) Insectivore (flycatcher) Grain eater (Grosbeak) Seed Eater (Crossbill) Fishing/piercing (Kingfisher) f. Netting fish (Pelican) g. Filter feeder (Flamingo) h. Surface Probing (Avocet) i. Probing worms (Ibisbill) j. Surface Skimming for fish (Skimmer) k. Raptor (Harris Hawk) 10/22/12 “Butterfly Blending” INB P. 89 Sponge: Watch the movie “Masters of Disguise” and answer the following question. 1. How do birds find caterpillars? By looking for leaves with holes in them. 2. How does the hornworm caterpillar “cover it’s tracks” to avoid predators? It chews the leaf quickly and evenly. Now you see me, now you don’t! Traits are inherited and some traits make it easier for living things to survive and reproduce. Camouflage is a trait that makes it very hard to see an animal in its natural habitat. Camouflage is an important part of their survival. It hides the animal from its predators while, at the same time, making the animal a sneaky predator itself. An animal that is best camouflaged in its environment has the best chance to survive, reproduce, and pass its color pattern on. Natural Selection Example: The Peppered Moth There are two phenotypes for a type of moth found in England: black and white speckled. Before the Industrial Revolution, the white “peppered moth” was had the largest population because they matched the light colored bark on the trees. This meant that birds couldn’t spot them and eat them, so they lived. longer. The Peppered Moth When the Industrial Revolution happened, the factories poured out black smoke, covering the white trees with black soot. This caused the white moths to stand out, and the birds ate them sooner than the black ones. The black moth population then grew rapidly because the birds were not naturally selecting them. If this progression were to continue for generations and generations, the gene for the white moths may be completely eliminated from the species. In other words, the birds would cause all of the white moths to go extinct because of evolution. Concealing Coloration – when an animal blends in with its background Octopus Video Disruptive coloration – when an organism’s color is broken up with other patterns like stripes or spots so it doesn’t stick out against the background Mimicry – when an animal copies or mimics a color or form of something else. Blending Butterflies Purpose: To explore and simulate camouflage in animals Materials: Butterfly pattern, colored pencils, markers or crayons Procedure: 1. Write your name on the back of your butterfly. 2. Design a butterfly so that it can be hidden/camouflaged somewhere in the classroom. 3. Make the butterfly as invisible as possible. 4. Cut out the butterfly. Tape the butterfly to it’s hiding spot. Natural Selection In our Blending Butterflies activity, you were able to show how natural selection works. Those butterflies that blended in have the traits that help them to survive. Those that didn’t blend in, do not have those traits. Organisms that do not have the necessary traits to survive in the environment will not live as long as those that do have the traits. Therefore, they will not be able to reproduce as much as the organisms that live a long time. More organisms with the desired traits will live from generation to generation. This process is known as natural selection. Factors that can affect Natural Selection: Overproduction - more offspring = fewer resources Variations – if there is no variation, all species will have the same traits and an equal chance of surviving and reproducing. Competition - organisms compete or fight over resources Selection - favorable traits are more likely to be passed on while unfavorable ones disappear Environmental change - changes in the surroundings 10/18/12 “Who Wants to Live a Million Years” INB P. 85 Sponge: P. 177-178: 1. What factors did Darwin identify that can cause natural selection? Overproduction, competition, and variations. 2. How would competition for food during an ice age result in natural selection? Organisms that are best adapted to finding food will survive and produce offspring and those that aren’t adapted will die. Remember that Natural Selection is what DRIVES EVOLUTION! Let’s see natural selection and evolution in action as we play “Who wants to live a million years?” Complete the activity on the front of your INB sheet as we go through this interactive evolution website. 10/23/12 “How Old is that Fossil?” INB P. 89 Sponge: P. 173: 1. What is a fossil and why was Darwin puzzled by them? Fossils are the preserved remains or traces of an organism. He was puzzled because the fossils he found were similar but much larger than organisms alive today. P. 184: 2. What are homologous structures? Give an example. Similar structures that related species have inherited from a common ancestor. Ex. The arm bones of a human, cow, horse, whale, and bird are the same. Evidence of Evolution: Fossil Record Fossils are the solidified remains or imprints of once-living organisms. Most fossils are found in the layers of Earth. The older a fossil is, the further down in the rock layer it is. Organisms that resemble the living creatures of today are mostly found in top layers, while more ancestral forms are found lower in the rock layers. This is called relative dating. How old is that fossil? We can estimate an AGE of a fossil using absolute dating: Rocks contain radioactive chemicals that break down. The half-life is the amount of time it takes for half of the chemicals in a rock to decay, and turn into another chemical. We analyze a sample of the chemical from a radioactive rock found near the fossil to determine how old the fossil is. Reading the Fossil Record • • Fossils found in the upper, newer layers of Earth resemble the organisms of today. Deeper fossils look less like present-day organisms. We use these fossils to trace the evolutionary history of organisms. Gaps in the Fossil Record • • • • Not every organism leaves a fossil No fossils = gaps in the fossil record Scientists call the gaps “missing links” If missing links are found, they may connect an older species to a more recent one • Gaps can be caused by: – Mass extinctions –entire species die off – Rate of evolution - scientists are not sure if species change gradually or quickly Half-life Activity Different chemicals have different half-lives. For our example, we are going to use carbon-14. Carbon-14 is a radioactive element. This means that it is an unstable substance. The atoms of carbon-14 change to another element, Nitrogen. It takes about 5,700 years for half of the atoms in a sample of carbon-14 to change to stable nitrogen. This period of time is known as the halflife of carbon-14. All living things contain carbon-14. Plants take-in carbon dioxide during photosynthesis and therefore also take-in carbon-14. When animals eat the plants, the carbon-14 is transferred to the animals. When a plant or animal dies (they are no longer taking in carbon), the carbon within it begins to change (decay) to nitrogen. After a while, all of the carbon-14 will decay to nitrogen. 1. Draw 100 dots in box 1. After 5,700 years, if it is cut in half, how many dots should I have left? Draw the new amount of dots in box 2. 2. What would happen after box 2 if another 5,700 years passed (box 3)? Would all the dots be gone? For each half-life draw the number of dots that would be left as you go through each box. 3. Then after 5,700 more years (box 4) how much would be left? 4. a. If something died 5,700 years ago how much of a percentage is left? b. If it has been 11,400 years how much is left? c. 17,100 years? 5. Using boxes1-6 above, how many total years have passed since this organism died? 6. What would be the amount left if another 5,700 years passed after box 6 (box 7)? Notice how after a little while it becomes so small that we can hardly see it anymore. That is the point at which carbon dating is no longer useful. So we need to find something with a longer half-life to date older things. We use ones with VERY long half-lives to date the earth. You have recently discovered the fossilized remains of a woolly mammoth. On the piece of paper in front of you, draw your best woolly mammoth. Be sure to fill up the whole piece of paper. This will represent all of the carbon-14 that was present in the woolly mammoth when it died. Cut the sample in half. Continue cutting one-half of your mammoth in half, again and again until the box is so small that it is not possible to make another cut. Each time you make a cut, make a mark in the box on your paper below. Conclusion Questions 1. What is the total number of times you were (practically) able to cut the sample in half? 2. Each cut represents the half-life period of carbon-14. What is the length of time represented by each cut? 3. Multiply the number of cuts by the half-life period of carbon14. What is the total amount of time represented by all of your cuts? 4. If an animal lived near and died in the LaBrea Tar Pits (found now in Los Angeles, California) 40,000 years ago, could carbon-14 be used to determine when it died? 5. If an animal lived millions of years ago, could carbon-14 be used when it died? Why or why not? 6. If the initial amount of carbon-14 in the mammoth was 8 grams, how many half-lives have passed if the fossil sample has 1 gram left? How may years have passed since the mammoth’s death? 10/24/12 “Evolution of the Whales” INB P. 93 Sponge: P. 183-184: 1. How do the similarities in early development provide evidence of evolution? A dorsal hollow nerve chord, a tail, and gill slits provide evidence for a common ancestor among vertebrates. 2. How are the structures of dolphin's flipper, a bird's wing, a dog's front leg, and a human arm similar? They all have the same bones, a humerus, radius, ulna, and phalanges. Whales are mammals, just like you, and their ancestors once lived on land. How do we know this? There are several ways that we can determine if organisms are related to one another. Homologous Structures Sometimes, scientists can look at the homologous structures shared by the two organisms. Remember that a homologous structure is a structure that shows how certain species have inherited a trait from an ancestor. The human arm, a bird’s wing, a dolphin’s pectoral fin, a dog’s front leg, and even a whale’s fin all have a very similar bone structure. Missing Link: The Archaeopertyx Similarities in DNA We can also compare the DNA to note how many base pairs match up. Our DNA and a chimpanzee’s are 99% the same, demonstrating that we are related to one another. Evidence of Evolution: Comparing Organisms Another method that scientists use to provide evidence of relatedness and for evolution is embryological evidence. We can observe the embryonic development of various species of organisms to see if they are related. For example, the chart above shows the development of a fish, lizard, dog, chicken, and human. Although they are not all mammals, they all share related development because they are all vertebrates – they have a backbone. Anyhow, back to the whales… so how did they come to live in the ocean? On the inside of your sheet, you will see steps to reconstruct the evolution of the whale from land to sea. Read the descriptions and use the traits drawn on the front to help you draw the journey of the ancestral whale to present day. Evolution of the Whale Based on the fossil record, and because whales are air-breathing mammals, scientists believe that they must have descended from a land dwelling mammal, such as the Mesonychid that lived near the ocean 55 million years ago. Evolution of the Whale Mesonychid evolved into a wolf-sized meat-eater called Pakicetus. Pakicetus ate primarily fish. These animals were fur covered and had a head that was becoming whale-shaped with sharp teeth. They lived near the ocean 50 million years ago. Evolution of the Whale Eventually, the Pakicetus developed into another land dwelling animal with shorter legs and webbed feet called the Ambulocetus (48 million years ago). This animal was able to swim well due to webbed feet and was therefore able to survive off of the abundant supply of food in the ocean (natural selection.) Ambulocetus’ head is long and narrow and resembles a lizard’s. Evolution of the Whale Rodhocetus appeared in the fossil record 46 million years ago. This animal resembled modern whales, but had four legs like a land dwelling animal. It’s hind legs were reduced (smaller) and it’s tail had a modified fin at the end, making it a better and stronger swimmer. It’s forelimbs are now fused together as a primitive flipper, and it’s head is similar to an alligator in shape. Evolution of the Whale Basilosaurus isis lived 37 million years ago. It’s body was more elongated and the modified tail became wider at the end, making it an even stronger swimmer. The hindlimbs are very reduced and barely visible as small flipper-like appendages. It’s head was similar to a dolphin in shape. Evolution of the Whale Basilosaurus evolved into the most recent ancestor of the modern-day whale, the Dorudon. Dorudon lived 34 million years ago and lived strictly in the sea. Their nostrils moved to the top of the head to become the blowhole and its forelimbs are paddle-like flippers. The hindlimbs are absent. Let’s see evolution in action! Watch as the whale ancestor’s you just created evolve into a modern day whale! 10/26/12 Bill Nye, “Evolution” INB P. 95 Sponge: P. 186-187: 1. How do new species form? When a group of individual remains isolated long enough from the rest of the species to evolve different traits. 2. Why do scientists believe that the Kaibab squirrel and Abert's squirrel will one day form two different species? The two squirrels are seperated by the grand canyon and will one day evolve different traits through DNA mutation to form new species. Bill Nye: Evolution Now watch this segment with Bill Nye as he discusses Evolution!