Station 1: Fossil Records 1. First, write the scientific definition of the following key terms in your NB, under the heading Fossil Records, write definitions in your own words but be sure not to leave out important parts. Fossil Sedimentary rock Natural selection Next, examine the diagram (left) to answer the questions below in complete sentences. 2. Explain what this diagram is communicating. 3. Is this diagram showing direct evidence or an inference based on reasoning? Explain. This diagram shows insects and a lizard trapped in fossilized tree sap (amber) from millions of years ago and how they look today. 4. Explain how organisms could not change over time and natural selection still be true and happening?
Which layers are oldest? Can you put them in order from youngest to oldest?
Station 7: Descent with modification Examine the diagrams and descriptions in the table about horse evolution on the back and use that information to answer the questions in complete sentences in your NB 1. Define: Descent with modification 2. Hyracotherium lived in a dense forest area dominated by a rich undergrowth of ferns. Discuss why the small body size might be an advantage in this type of environment? 3. A change in vegetation from dense forest to grasslands occurred due to climate changes and this selected for changes in the shape of the horse s leg and body size. Explain how these changes in vegetation could lead to the evolution of the horse. 4. The teeth of the browsers* (such as Mesohippus) were covered with a thick layer of enamel (hard outer-coating of teeth). The teeth of the modern-day horses, by comparison, have less enamel and appear to be much wider and flatter. Provide scientific reasoning to explain these changes seen in horse teeth over time. *Browsers vs. Grazers: Browsers strip off and eat leaves, bark, and green stems from plants, while grazers clip vegetation like grasses at or near ground level. Deer, such as white-tailed deer in the Rocky Mountains, are browsers. The disadvantage of browsing is that height may make vegetation inaccessible (hence the long neck of the browsing giraffe), and often-times browsers eat parts of the vegetation that are low in nutrients, chemically defended (bitter/poisonous), or both. Grazers, such as sheep and cattle, can feed on the much more nutrient-rich grasses. Examine the images of modern horse variations at left. 5. All of these variations have come about in the last 4,000 to 6,000 years as humans domesticated horses for work, travel, and show. Explain how all of these variations can happen in such a relatively short period of time when previous changes took millions of years.
Hyracotherium 37 million years ago Mesohippus 24 million years ago Merychippus 5 million years ago Pliohippus 1.6 million years ago Equus modern-day horse EVIDENCE OF EVOLUTION STATIONS Time frame Diagram Description of horse This horse lives in the grassy plains area It eats grasses and is classified as a grazer It is approximately 1.6 m (5.2 ft.) tall It has a single visible digit This horse lived in areas with shrubs and on the grassy plains It ate grasses and is classified as a grazer It was approximately 1.0 m (3.2 ft.) tall It had a single visible digit This horse lived in areas with shrubs and on the grassy plains It ate leafy vegetation and grasses and is classified as a grazer It was approximately 1.0 m (3.2 ft.) tall It has three visible digits This horse lived in thinly wooded areas. It ate leafy vegetation and is classified as a browser It was approximately the size of a small dog, about 0.6m (2 ft.) tall It had four visible digits This horse lived in thickly wooded areas It ate leafy vegetation and is classified as a browser It was approximately the size of a small dog, about 0.4 m (1.3 ft.) tall It had four visible digits
Station 2: Vestigial structures Examine the diagrams and visuals below with your group. Based on your observations and discussion, answer the following questions in complete sentences. 1. Write a definition of a vestigial structure. 2. Name 3 vestigial organs that humans have and hypothesize what their purpose probably was. 3. Explain why snake legs are vestigial. 4. Explain the scientific reasoning of how a vestigial organ is evidence of evolution. Snakes evolved from four legged animals similar to lizards. Most species of snakes have lost all traces of limbs but snakes in the boa and python family have a tiny pair of hind legs. Unlike whales, the python's (or boa's) vestigial legs can actually be seen as a pair of "spurs" that stick out where the body ends and the tail begins. (Admittedly, it is difficult for an untrained person to tell where that is!) The vermiform appendix had digestive functions in the ancestral human species, probably helping the cellulose in grass breakdown in the intestine, as they were herbivours. The appendix has become vestigial in human beings because they have become very small in size and don t contribute in cellulose fermentation. However, several appendix problems occur in people and the removal of this part in the body will do no harm and is relatively common. Whales still have bones (not seen from outside) that are remnants from hind legs.
Station 3: Comparative Anatomy & Homologous Structures Analyze the diagram above then answer the following questions in complete sentences after discussing with your group. 1. Describe how the limbs of these seven organisms are similar and how are they different. 2. Explain why they are so similar in structure and yet can be used differently by the organism? How did this happen? 3. What does this help explain about how related or not these species are to each other? 4. Explain how these structures are evidence of evolution. This picture of bones is from a seal fin I found on the beach. My own piece of evidence collected from a backpacking trip to the Lost Coast in Northern California, summer 2013 (Me and a member of the Pinniped family (seals) both gesturing for world peace).
Station 4: Comparative Embryology Examine the diagrams of four different vertebrate organisms at the early embryo stage. Discuss differences with your group and then answer the questions in complete sentences. 1. Try to determine which embryo will develop into which organism- reptile, human, bird, fish. 2. Which ones out of the four do you think are most closely related, and why? 3. After reading the passage below, construct an explanation for which animal is more closely related to humans- chickens or fish? (put answer in CER format, complete sentences) Claim: Evidence: Reasoning:
Station 5: Genetic Evidence Gene sequence & protein sequences comparisons DNA is the code for making proteins, the closer the DNA, the closer the amino acid sequence, and thus the closer the final proteins are. Analyze the following data with your group: Amino Acid Sequences Baboon ASN THR THR GLY ASP GLU VAL ASP ASP SER PRO GLY GLY ASN ASN Chimp SER THR ALA GLY ASP GLU VAL GLU ASP THR PRO GLY GLY ALA ASN Lemur ALA THR SER GLY GLU LYS VAL GLU ASP SER PRO GLY SER HIS ASN Gorilla SER THR ALA GLY ASP GLU VAL GLU ASP THR PRO GLY GLY ALA ASN Human SER THR ALA GLY ASP GLU VAL GLU ASP THR PRO GLY GLY ALA ASN 1. For each primate in the table above, count the number of amino acids that are different from the human sequence. Record these numbers in a data table on your handout, draw one like the one shown below. 2. Calculate the percentage of differences of each primate compared to humans by dividing the number of amino acid differences by 15 and then multiplying by 100. Record these numbers in the data table you drew as well. Primate Baboon Chimpanzee Gorilla Lemur # of Amino Acids Different from Humans Percent Difference 3. Use this data to create a graph to better communicate your findings. Remember which graph type is good for comparing categories? Include title, label each axis with x and y AND the label (category/unit), make a key, include an appropriate scale. 4. Are your results surprising? Why or why not?
Chromosome comparisons: Another line of genetic evidence 5. Summarize the argument: what evidence exists that humans and great apes shared a common ancestor?
Station Six: Biogeography 1. Define Biogeography 2. Define a species 3. How did these three members of the camel family become different species? Claim: Evidence: Reasoning:
Biogeography Cont. Endemism is the ecological state of a species being unique to a defined geographic location, such as an island, nation, country or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. Madagascar an island off the coast of Africa has some of the world's most interesting animals. About 75 percent of the species found in Madagascar are endemic, found nowhere else on the planet. 1.) What kind of selection would be responsible for giving rise to so many different species on this one island? Would it be a different kind of selection for just the endemic species? What is doing the selecting?
Station 8: Evolution of a Scientific Theory Building Ideas to Explain How Evolution Happens 1.) Science is a communal effort- which scientists laid the foundation for Darwin s theory of natural selection? What ideas did they contribute that were crucial for Darwin to build on? (see back side) 2.) What do we know now about DNA and genetics that further disproves LaMarck s theory? 2.) Are humans subject to natural selection? Does our human population have all 4 required factors?