Science Learning Packet BIO B: Evolution Packet

science learning activities for SPS students during the COVID-19 school closure.

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Due to the COVID-19 closure, teachers were asked to provide packets of home activities. This is not intended to take the place of regular classroom instruction but will help supplement student learning and provide opportunities for student learning while they are absent from school. Assignments are not required or graded. Because of the unprecedented nature of this health crisis and the District’s swift closure, some home activities may not be accessible.

If you have difficulty accessing the material or have any questions, please contact your student’s teacher. Take Home Packet High School Biology B – Evolution

The goal of Evolution is for students to understand changes in populations of organisms over time. This unit builds on student’s prior learning, particularly genetics. By the end of the unit, students will be able to predict and explain how species have changed over time in response to changes in environmental conditions. Students will use multiple lines of evidence to identify variation in the heritable traits of individuals in a population, ecological factors that influence survival and reproduction, and the interaction between variation and ecology to produce changes in populations such as adaptation, speciation, and extinction.

Why should you do this? These materials will help you continue your learning at home. The unit addresses content that is not covered in any other high school science course. Goals are listed for each activity to help you track your learning. Your teacher will provide information on which item(s) will be submitted, when they are due, and how they will be submitted.

This unit is designed to address the following Washington State Science Standards (Next Generation Science Standards):

Performance Expectations LS3-3: Apply concepts of statistics and probability to explain the variation and distribution of expressed traits in a population.

LS2-8: Evaluate evidence for the role of group behavior on individual and species’ chances to survive and reproduce.

LS4-1: Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.

LS4-2: Construct an explanation based on evidence that the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the proliferation of those organisms that are better able to survive and reproduce in the environment.

LS4-3: Apply concepts of statistics and probability to support explanations that organisms with an advantageous heritable trait tend to increase in proportion to organisms lacking this trait.

LS4-4: Construct an explanation based on evidence for how natural selection leads to adaptation of populations.

LS4-5: Evaluate the evidence supporting claims that changes in environmental conditions may result in (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.

Science and Engineering Practices: Constructing Explanations, Developing and Using Models Crosscutting Concepts: Systems and System Models, Structure and Function

What resources do I need? This packet, a pencil or pen, and scrap paper. You may find it useful to have a highlighter and markers or colored pencils, but this isn’t required. We recommend that you call a friend to talk through the lessons and/or share your learning with someone in your household.

What about online resources? This packet references several videos and websites that you can access with a phone. If you don’t have internet access on your phone, you may find it helpful to call or text a friend to ask questions. If this is not possible, just skip those suggestions and use the materials in the packet.

What resources do I have to be successful? If you can access Schoology, your teacher may be providing resources on their class webpage. If not, everything you need is in this packet. You can also ask questions of your teacher by sending them an email or contacting them using their usual procedure. Timeline: This packet will take 2-3 weeks to complete. Below we have provided a suggestion on how you might work through the materials. Your teacher may provide a modified version of this schedule on their Schoology page. Please adjust for you / your family.

Unit Driving Question: How does the environment impact species over time? How will species change or adapt?

Lesson Name Extensions 1 Evolution Initial Ideas Video – Stated Clearly: What is Evolution? Make an entry in the Discussion on your teacher’s Schoology page (if provided) 00 Learning Tracking Tool 2.1 Malaria and SCD Demo Start 2.1 Malaria and SCD Reading and Worksheet Finish 2.1 Malaria and SCD Reading and Worksheet 2.2 Malaria and SCD - Evolution Tool 00 Learning Tracking Tool Make an entry in the Discussion on your teacher’s Schoology page (if provided) 3.1 Rules We Learned from SCD 3.1 OPTIONAL Evolution Lecture with Sean Carroll 3.2 Comparing Models Video – Stated Clearly: What is Natural Selection? 00 Learning Tracking Tool 4 Introduction to Human Evolution Start 4 Human Evolution Activities Worksheet Finish 4 Human Evolution Activities Worksheet Explore the videos and interactives from PBS’s series Your Inner Fish 00 Learning Tracking Tool 5.1 Investigating Skin Pigmentation 5.1 Skin Pigment Questions 5.2 Skin Pigmentation – Evolution Tool 00 Learning Tracking Tool entry Make an entry in the Discussion on your teacher’s Schoology page (if provided) 6.1 Explaining Other Examples Video – Stated Clearly: Does The Theory of Evolution really matter? 6.1 OPTIONAL Introduction to Geologic Time PBS Deep Time Interactive HHMI Making of Mass Extinctions interactive timeline Videos – PBS Eons 6.2 Student Self-Assessment Catch-Up Day (or explore the extensions)

Name: ______Class: ______Learning Tracking Tool for Evolution: How does the environment impact species over time? How will species change or adapt?

What did we do? How can our learning be used to Self-Assess: What questions do I What did we figure out? explain the phenomenon? have? Where am I with my Summarize key information and Describe what you will you add to your understanding of the What additional activities with a description and/or explanation of the phenomenon. phenomenon? information do you need to understand the Lesson picture. (Example: Ready to explain, starting to get it, phenomenon? need more information)

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How to use this PowerPoint • Work at your own pace. Your health and your family come first. • If possible, you might find it helpful to go through activities at the same time as a peer. Then you can communicate through text, email, or a call if you have questions or to share ideas. • You might find it helpful to have a piece of scrap paper and a pencil or pen to record questions 1 Evolution Initial Ideas or ideas. • Read through the slides one at a time. Take your time to explore the images and any links. How does the environment impact species over time? • If you come across something you don’t understand, make a note of which slide you are on and How will species change or adapt? come back to it after you go through the whole PowerPoint. If you are still confused, feel free to email your teacher with a question. You could also ask someone in your household or reach out to a peer through text, email, or a call. • When you finish, consider sharing what you learned with someone in your household or a friend through text, email, or a call. Explaining your thinking will help you to retain and make sense of the information.

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Goals Warm Up – Answer on a sheet of scrap paper

After reviewing this PowerPoint, you should be able to: 1)Define “evolution.” 1. What do you think “evolution” means? 2)Define “scientific theory” and explain why evolution is not 2. What do you think of when you hear the word “just a theory.” “evolution”? 3)Identify several things that you notice from a video and several questions that you have about how Sickle Cell Disease evolved and persisted in populations.

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Evolution as a scientific theory Watch this video to learn more about the What is evolution? terms “theory” and “law.” A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in Evolution is the change in the heritable characteristics of accordance with the scientific method, biological populations over successive generations. These using accepted protocols of observation, measurement, and evaluation of results. characteristics are the expressions of genes that are passed on from parent to offspring during reproduction.

Evolution is the process by which different kinds of living organisms are thought to have developed and diversified from earlier forms during the history of the earth.

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What is the evidence for evolution? The theory of evolution by natural selection is supported by evidence from Fossil comparative anatomy, embryology/development, the fossil record, DNA, and the geographic distribution of species on Earth. Record Scientists use Comparative Anatomy fossils to Scientists compare structures to identify understand organisms that may share a common when and ancestor or to identify species that where species independently evolved similar structures to evolved and the survive in their environment. relationships between Embryology/Development species. Scientists identify patterns in the development of organisms from a single cell into complex multicellular organisms. Video: “What is Think back to the Genetics: Development a fossil? Unit!

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DNA Scientists compare the DNA of species. Evolution Unit Driving Questions

How does the environment impact Geographic Distribution of Species Polar bears live only at the North Pole species over time? and penguins only at the South Pole.

Australia is home to a lot of marsupial How will species change mammals, including many that look or adapt? like placental mammals that live elsewhere on Earth.

Check out this video to learn more about the evidence for evolution. 10 9 10

What did we learn about the evolution of Video: Sickle Cell Disease and Malaria Sickle Cell Disease?

On the Schoology Discussion Board for Lesson 1 create a post to share your Make a T-chart to record your notes: learning and ideas: What I notice: What I wonder: 1. List as many learnings as you can. • • • • 2. What questions do you have about the evolution of Sickle Cell • • Disease? • • 3. How do you think this might relate to things you learned previously about genetics and inheritance?

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You will use your understanding of Ecology and Genetics to investigate and explain how species evolved: Check Your Understanding Evolution Three Questions 1)Define “evolution.” Variation: What differences are there among individuals in 2)Define “scientific theory” and explain why evolution is not “just a the population? theory.” 3)Identify several things that you notice from a video and several Ecology: What factors affect the survival and reproduction questions that you have about how Sickle Cell Disease evolved and of individuals in the population? persisted in populations. What’s Next? Interactions between Variations and Ecology: What 1. Post to the Discussion board on your teacher’s Schoology page (if provided). changes have occurred in the population? (over time or in 2. Make a new entry in your Learning Tracking Tool titled “1 Evolution Initial Ideas.” different areas) 3. Consider watching the optional video – Stated Clearly: What is Evolution?

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4 https://science.howstuffworks.com/life/evolution/question609.htm What is a fossil?

A fossil of a Microraptor from a 130-million year old forest that existed in what is now Liaoning Province, China is displayed at the American Museum of Natural History in New York City. GETTY IMAGES

The term fossil describes a wide range of natural artifacts. Generally speaking, a fossil is any evidence of past plant or animal life that is preserved in the material of the Earth's crust. But when most people talk about fossils, they mean a specific subsection of this group -- fossils in which the shape of the animal or plant has been preserved, while the actual organic matter of its body is gone. These amazing remnants, which date to prehistoric times, were formed very slowly by dynamic geological processes.

In most cases, the fossilization process began when a plant or animal died and was quickly covered with sediments, usually at the bottom of a body of water. The loose sediments protected the bodily remains from the elements, bacteria and other forces that cause weathering and decay. This slowed the decaying process down so that some of the remains (in most cases, only hard material like bone or shell) were preserved for thousands of years. During this time, sediment layers continued to collect above the bone. Eventually, these sediment layers became hard, solid rock.

Sometime after this hard rock layer formed, water percolated down through the rock and washed the preserved remains away. Since the rock above was hard and rigid, it didn't fall down into the empty space where the remains used to be. This empty space formed a natural mold of the animal, perfectly preserving the shape of the original remains. In some cases, percolating water carried minerals into the mold. These minerals hardened to make a natural cast of the form, just as an artist might make a sculpture cast by filling a mold with plaster. All the original organic material disappeared, but nature left a precise mineral reproduction of the plant or animal remains. In cases where minerals did not fill the mold, paleontologists may fill it themselves, creating an artificial cast.

This is just one scenario of fossil creation, of course -- there are all sorts of other ways nature might form a fossil. A lot of prehistoric insects, for example, have been fossilized in amber. This sort of fossilization occurred when the insect was enveloped in the liquid sap from a tree. Just like the sediments at the bottom of a body of water, the sap material protected the insect from decay and eventually hardened. Animal fossils are also found in tar pits, bogs, quicksand and volcanic ash.

Another interesting fossil type is petrified wood. Petrified wood generally forms when trees fall into a river, where they become saturated and then buried in mud, ash, silt and other materials. Minerals, such as the silica in volcanic ash, seep into the tree and fill in tiny pores in wood's cells. This changes the overall composition of the wood, turning it into stone material, while preserving its original structure. The variety of minerals in petrified wood creates striking vivid colors.

In addition to fossilized plant and animal bodily remains, paleontologists study fossilized animal footprints and trails, and even fossilized animal dung (called coprolite). These fossils are enlightening because they reveal something about how prehistoric animals moved and what they ate.

The fossil record, the total collection of fossils in the world, is extraordinarily important to our understanding of the Earth's history. Fossils tell us which plants and animals existed in prehistoric times, and where they lived. They also tell us something about when they lived. Based on the position of fossils in the layers of the Earth's crust, paleontologists can determine which animals predate other animals and which animals lived at the same time.

Using carbon dating, paleontologists can sometimes estimate the age of fossils. This provides the age of the rock layer where the fossil was found, which helps scientists date all the other material at that level. Without fossils, we would have a much more incomplete picture of Earth's early history.

The Making of the Fittest: Natural Selection in Humans

[NARRATOR:] Davaun and Skyy Cooper are brother and sister. Both of them have sickle cell anemia. Before the advent of modern medicine, sickle cell anemia almost certainly meant death before adulthood. Even today, young patients can suffer strokes and organ failure. Sickle cell anemia is a genetic disease. Parents of those who have the disease might not have it themselves, but both must carry the sickle cell character in their DNA. Besides some bone pain, Skyy leads the fairly normal life of a 13 year-old girl. But her younger brother Davaun, has suffered acute chest syndrome and has already had his spleen removed.

[NARRATOR:] Skyy and Davaun's symptoms arise from the fact that some of their red blood cells become misshapen--crescents instead of discs--preventing enough oxygen from being delivered to all parts of the body. It's not completely clear why symptoms are variable, but what is most perplexing about sickle cell disease is that it is not rare.

[DR. HEENEY:] So, in the United States, we think there are between 70,000 and 125,000 persons with sickle cell disease. However, that doesn't take into account immigration and other patients or persons coming from other parts of the world into the country.

[NARRATOR:] In fact, in some populations--African Americans, for example--the incidence is as high as 1 in 500, astoundingly high for a deadly inherited disease. Didn't Darwin teach us that harmful traits disappear from the gene pool through natural selection? Why is sickle cell anemia so prevalent, and why in particular among people of African descent? The answers to these questions began with a remarkable set of observations from an unlikely person more than sixty years ago.

[NARRATOR:] Tony Allison has spent most of his career as a medical doctor and molecular biologist in the U.S. and England. But he grew up in East Africa and he is quick to recall his formative years in Kenya.

[DR. ALLISON:] We lived in the upcountry, and we used to go to the coast every year in August for the holiday when it was a little bit cooler than at other times. So we had the trip all the way down, which was usually with a truck and a car. And, so we would camp on the way and, in Tsavo and there would be lions roaring around, so it was really quite exciting.

[DR. CARROLL:] These are the infamous Tsavo lions--

[DR. ALLISON:] The famous--

[DR. CARROLL:] Right?

[DR. ALLISON:] infamous Tsavo lions--

[DR. CARROLL:] Around 1950, biologists didn't know a lot about the details of evolution, because we didn't know really how heredity worked. The structure of DNA had not been discovered yet, genetic code had not been cracked. So, we know that while evolution was due to genetic changes, we didn't know how those genetic changes took place whatsoever. So, there were holes in the whole picture of the evolutionary process, and Tony Allison was probably the least-likely person you would imagine, who would fill one of the most critical holes. He grew up far away from the centers of science in Europe and North America. He was really interested in natural history and he loved the Kenyan wildlife, and he visited archeological digs that were going on at the time. But it was a really circuitous and serendipitous route that led him to an enormous discovery in evolutionary biology.

[NARRATOR:] Tony first went to University in South Africa where he studied physical anthropology, then to medical school at Oxford. He had a deep interest in human origins, but not so much in ancient stones and bones. Tony was interested in blood. Could the common ABO blood types say anything about the evolutionary history of East African tribal people?

[DR. ALLISON:] And I actually learned just before going out about the sickle cell condition. Nobody really knew the frequencies of sickle cells in East Africa. So it was a barren slate, so to speak.

[NARRATOR:] Blood samples from people carrying the sickle cell character appear quite normal--until oxygen is removed. Tony learned that adding a chemical agent to the samples would quickly reduce oxygen and reveal sickle cells, if they were there. This gave him an easy test to score blood samples for the sickle cell character.

[DR. ALLISON:] But what was striking was that you had high frequencies of people carrying the sickle cell character in the coast and near Lake Victoria, and very low frequencies in the high country in-between, in Nairobi.

[NARRATOR:] What could possibly account for such a striking disparity? The sickle cell character was understood to be genetic, not environmental. Tony had grown up in the dry Kenyan highlands, but he knew the warm, moist lowlands were a breeding ground for the anopheles mosquito that carried the malaria parasite, Plasmodium falciparum.

[DR. CARROLL:] And it dawned on him, the places where there was a really high incidence of sickle cell was where there was a really high incidence of malaria. Bang.

[NARRATOR:] Now it was a burning question that confronted Tony: could sickle cell and malaria be connected? And if so, how? It was a radical notion that a genetic disease could somehow be connected to an infection.

[DR. CARROLL:] When you went back to Oxford--you had this idea of a linkage between sickle cell and malaria, but you hadn't published it? Did you know it was a big deal? I mean, did you...

[DR. ALLISON:] I was sure it was a big deal. Yes. That's why I wanted not to go off half- cocked. I wanted to have a really complete story.

[DR. CARROLL:] So, he decided he had to sit on this idea until he got a chance to test it properly. So… and a key element of the scientific method is, to come up with a hypothesis, that's great. But you've got to test it in every way possible to see whether or not it can hold up to that sort of scrutiny. That's how science moves forward.

[DR. ALLISON:] The scientific method essentially means that you address a problem and try to find a solution. So you look at children of the appropriate age and find out whether they are, in fact, protected against malaria. And if that's the case, you predict that you will have high frequencies of sickle cells only in areas where malaria is endemic.

[DR. CARROLL:] He wanted to know that this correlation held, not just in Kenya, but everywhere.

[NARRATOR:] It would be important to look directly at the incidence of malaria and sickle cell in as many areas as possible. So, Tony went on a sickle-cell safari.

[DR. CARROLL:] He wanted to gather blood samples from all over East Africa to really test this correlation. And now he was a trained medical doc, so he had something to offer. So he would go into the market on market day, and offer to do checkups on children. And just take a little finger prick or a little heel prick to get a little sample of blood.

[NARRATOR:] The first thing he did was look at the malaria parasite load in each sample. Then he tested for the sickle cell character. He found that children carrying the character had a lower parasite count, as if they were partially protected against malaria.

[DR. CARROLL:] And when he examined the blood of about 5,000 individuals, a really massive study, the correlation was really clear. So clear, in fact, that he could really draw a map of East Africa, and shade in the areas of high incidence of sickle cell, and they were superimposed right on top of the areas of high incidence of malaria. Bang, that was it.

[NARRATOR:] The many samples and detailed maps made it clear there was a connection between sickle cell and malaria. But to understand how sickle cell might protect people from malaria required thinking about the genetics of sickle cell.

[DR. ALLISON:] What happens is the genes are lined up on chromosomes. And one has pairs of them with the exception of the sex chromosomes. And this means that you have two copies. So the copies can be the same or they can be different. And if they're the same, they're called homozygous. And if they're different, they're called heterozygous.

[NARRATOR:] When an individual finds a partner and reproduces, one of each pair of chromosomes is passed on. If the parents are both heterozygous, carrying one sickle cell and one normal gene, odds are one in four that the child will be sickle cell homozygous, two in four that the child will be heterozygous, and one in four that the child will carry two copies of the normal gene. In the absence of malaria, there is strong selection against the sickle cell gene. However, in a malarial environment, individuals born with two copies of the sickle cell gene, and those born with two copies of the normal gene, are both at a disadvantage. One gets sickle cell disease, the other is most vulnerable to malaria. Tony's brilliant insight was that those that carried just one sickle cell gene had an innate resistance to malaria. Malaria tipped the selective balance in favor of heterozygotes. The evolutionary trade-off is that protection from malaria comes at the cost of more sickle cell disease in the population. The sickle cell mutation was not the best genetic solution you might imagine to resist malaria. That's not how evolution works. It was the most available--a simple typo, A to T, in the gene that encodes hemoglobin.

[DR. CARROLL:] Mistakes are made in the copying of DNA in every generation. You and I were born with about 40 or 50 mutations that didn't exist in either of our parents. It's just part of the nature of copying three billion letters in the process of reproduction. And when those mistakes arise, a typo arises in the globin gene... for most of us, that would be a bad thing. But if you live in a malarial area, it gives you an edge against the malarial parasite, so that mutation is retained.

[DR. ALLISON:] Well, fitness, essentially, is a measure of whether a particular gene is likely to be passed on to the next generation. And this means that for that to happen, the individual carrying that gene has to survive to reproductive age, and secondly has to reproduce.

[DR. CARROLL:] Now you had a sense that you had this explanation that was general to the prevalence of sickle cell and its correlation with malaria. But you didn't quite know the mechanism, right?

[DR. ALLISON:] That's right.

[DR. CARROLL:] So what did you do next?

[DR. ALLISON:] Well [laughs] I have to say I left that part of the story to others, because it's quite a complex story...

[NARRATOR:] A large body of subsequent research has shown that the sickle cell mutation compromises the ability of the parasite to reproduce. Thus, a mutation that creates one genetic disease can also protect against another disease.

[DR. CARROLL:] What Tony gave us was a fully-worked-out example of evolution by natural selection. And the amazing thing was, this was in humans. This is how natural selection was working on humans in real time in the real world. Tony's map of East Africa was a stunning achievement. But he could go further than that. He knew that there was a high incidence of sickle cell in Southern Europe, in Southern India, and in other parts of Africa. And it turns out, these were all malarial zones as well. And so, his map applied not just to East Africa, but that whole part of the world.

[DR. HEENEY:] When I'm explaining about the origins of sickle cell disease and its association with malaria to children or their families, they often look at me with incredulity. They don't understand, like, "You're kidding, right? This is all to do with a mosquito infection?" As our species has been able to move across the globe to areas with low malarial incidence, this gene is now really more of a nuisance than anything else. It's not really a clear selective advantage for them, in Boston, let's say. But it takes thousands of years for the population to change and for genetics to change based on the pressures around them in the environment.

[NARRATOR:] What Tony Allison did, first with his sharp intuition and then with his rigorous research, will stand as a monument, bringing our own evolutionary process into the light.

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How to use this PowerPoint • Work at your own pace. Your health and your family come first. • If possible, you might find it helpful to go through activities at the same time as a peer. Then you can communicate through text, email, or a call if you have 2.1 Malaria and Sickle Cell questions or to share ideas. • You might find it helpful to have a piece of scrap paper and a pencil or pen to Disease Demo record questions or ideas. • Read through the slides one at a time. Take your time to explore the images and any links. How does a fatal disease persist in a population? • If you come across something you don’t understand, make a note of which slide you are on and come back to it after you go through the whole PowerPoint. If you are still confused, feel free to email your teacher with a question. You could also ask someone in your household or reach out to a peer through text, email, or a call. • When you finish, consider sharing what you learned with someone in your household or a friend through text, email, or a call. Explaining your thinking will help you to retain and make sense of the information.

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Background: Goals Evolution and Allele Frequencies After reviewing this PowerPoint, you should be able to: 1)Explain how populations evolve (NOT individuals). 2)Describe evolution using the term “allele frequency.” 3)Analyze allele frequency data related to malaria and Sickle Cell Disease.

Video: “What is an allele?”

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Imagine a population of beetles. Beetles come in green and brown.

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What alleles are present in the gene pool? Evolution is change in allele frequencies How does the frequency of alleles change because alleles (DNA) produce heritable traits over generations?

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1: Parent Population Malaria and Sickle Cell Disease Demo There are two parts to this demo, Simulation 2 and Simulation 3. In both cases, the population starts as the “Parent Population” shown below. 1) Read and answer the questions on the first Answer these questions on your worksheet / paper: page of the “Malaria and SCD Reading and a) Identify the three genotypes for the gene that codes for Worksheet.” hemoglobin subunits in the parent population. What are the starting frequencies for each genotype? 2) Then review the data on the following slides b) What are the start allele frequencies for the A and S and answer the questions on the back of the alleles? worksheet. 3) In Lesson 2.2 you will explain the evolution of Sickle Cell Disease in areas with high and low levels of malaria.

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Simulation 2: Environment with no malaria Simulation 2: Environment with no malaria

The table below shows the genotypes and phenotypes of the The table below shows the genotypes and second generation of offspring in an environment where there phenotypes of the first generation of offspring in is little to no malaria. an environment where there is little to no Answer these questions on your worksheet / paper: c) How did the frequencies of the A and S alleles change malaria. over time? What are the trends? d) Explain the trends using your knowledge of Sickle Cell Disease.

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Analyze the graph and answer the Simulation 3: Environment with malaria question below: The table below shows the genotypes and phenotypes of the first generation of offspring in an environment where high rates of malaria infections occur. Remember to compare this to the Parent Population!

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Simulation 3: Environment with malaria Analyze the graphs and The table below shows the genotypes and phenotypes of the answer the second generation of offspring in an environment where high rates of malaria infections occur. questions below: Answer these questions on your worksheet / paper: e) How did the frequencies of the A and S alleles change g) Summarize the over time? What are the trends? trend for each f) Explain the trends using your knowledge of Sickle Cell genotype (AA, AS, Disease. SS) in Simulation 2 and Simulation 3. h) Do you think the trends will continue for Simulation 3? Explain why or why not.

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Check Your Understanding 1) Identify several things that you notice from a video and several questions that you have about Sickle Cell Disease. 2) Develop an initial model for how a fatal disease persists in a family. 3) Add details to your model at the organism, cellular, and atomic-molecular scales. What’s Next? 1) Look back at the predictions you made about what would happen in the demo. Were your hypotheses supported or not supported by the data? Explain. 2) Check your work using the provided key.

Name: ______Period: ______Malaria and Sickle Cell Disease Reading and Worksheet

Introduction:

In the United States, about 1 in 500 African-Americans develops Sickle Cell Disease. In Africa, about 1 in 100 individuals develops the disease. Why is the frequency of a potentially fatal disease so much higher in Africa?

The answer is related to another potentially fatal disease, malaria. Malaria is characterized by chills, fever, vomiting and severe headaches. Anemia and death may result. Malaria is caused by a protozoan parasite (Plasmodium) that is transmitted to humans by the Anapheles mosquito. When malarial parasites invade the bloodstream, the red cells that contain defective hemoglobin become sickled and die, trapping the parasites inside them and reducing infection.

Compared to AS heterozygotes, people with the AA genotype (normal hemoglobin) have a greater risk of dying from malaria. Individuals with the AS genotype do not develop Sickle Cell Disease and have less chance of contracting malaria. They are able to survive and reproduce in malaria-infected regions. Therefore, BOTH the A and S alleles of these people remain in the population. SS homozygotes have Sickle Cell Disease, which usually results in early death.

In a region where malaria is prevalent, the S allele confers a survival advantage on people who have one copy of the allele, and the otherwise harmful S allele is therefore maintained in the population at a relatively high frequency. This is the phenomenon that you will be exploring today.

The frequency of the S allele in malaria-infected regions of Africa is 16%, the sickle cell allele (S) is also widespread in the Mediterranean and other areas where malaria is or used to be a major threat to life. In contrast, the S allele frequency is only 4% in the United States, where malaria has been virtually eliminated. Compare the regions where Malaria is still a threat with the sickle cell rates in those areas:

What do you notice?

Demo:

Hypothesis/Prediction: What do you think will happen to the frequencies of A and S alleles as a result of the presence of malaria? (Will the frequency of A increase or decrease? What about S?

In areas with high malaria…. In areas with low malaria…

Answer the following questions as you review the slides with malaria and SCD demo data:

1: Parent Population

a) Identify the three genotypes for the gene that codes for hemoglobin subunits in the parent population. What are the starting frequencies for each genotype?

b) What are the start allele frequencies for the A and S alleles?

Simulation 2: No Malaria

c) How did the frequencies of the A and S alleles change over time? What are the trends?

d) Explain the trends using your knowledge of Sickle Cell Disease.

Graph: Provide two explanations for why the S allele persists after 5 generations.

Simulation 3: Malaria is present

e) How did the frequencies of the A and S alleles change over time? What are the trends?

f) Explain the trends using your knowledge of Sickle Cell Disease.

Graphs:

g) Summarize the trend for each genotype (AA, AS, SS) in Simulation 2 and Simulation 3.

h) Do you think the trends will continue for Simulation 3? Explain why or why not.

Look back at the predictions you made about what would happen in the demo. Were your hypotheses supported or not supported by the data? Explain.

Name: ______KEY______Period: ______Malaria and Sickle Cell Disease Reading and Worksheet

Introduction:

What do you notice? There is an overlap between regions where malaria is present and regions with high frequencies of the hemoglobin S allele for sickle cell.

Demo:

Hypothesis/Prediction: What do you think will happen to the frequencies of A and S alleles as a result of the presence of malaria? (Will the frequency of A increase or decrease? What about S?

In areas with high malaria…. In areas with low malaria… Hypothesis – no right or wrong answers! Hypothesis – no right or wrong answers!

Answer the following questions as you review the slides with malaria and SCD demo data:

1: Parent Population

a) Identify the three genotypes for the gene that codes for hemoglobin subunits in the parent population. What are the starting frequencies for each genotype?

AA – 25% AS – 50% SS – 25%

b) What are the start allele frequencies for the A and S alleles?

A – 50% S – 50%

Simulation 2: No Malaria

c) How did the frequencies of the A and S alleles change over time? What are the trends?

The A allele increased in frequency from 50% to 81% while the S allele decreased in frequency from 50% to 19%

d) Explain the trends using your knowledge of Sickle Cell Disease.

Having the genotype SS results in Sickle Cell Disease, which may affect an individual’s ability to survive and reproduce. This would result in a decrease in the amount of S alleles in the population because individuals with A alleles would be more likely to pass on their DNA.

In the absence of malaria, there is no benefit to having the S allele.

Graph: Provide two explanations for why the S allele persists after 5 generations.

First, there may not have been enough time for the allele to be completely eliminated from the population. Many more generations may be required. Second, in simulation 2, even though individuals with the sickle cell disease genotype (SS) were 100% selected against, individuals who were heterozygous (AS) had neither a selective advantage nor a selective disadvantage. The S allele can “hide” in the heterozygotes from generation to generation and persist in the population.

Simulation 3: Malaria is present

e) How did the frequencies of the A and S alleles change over time? What are the trends?

From the parent generation to the first generation the frequency of S alleles goes down from 50% to 32% and the A allele goes up from 50% to 68%. However, in the second generation the S allele increase from 32% to 39% and the A allele decrease from 68% to 61%.

f) Explain the trends using your knowledge of Sickle Cell Disease.

In an environment with malaria, there is still a disadvantage to having the genotype SS as those individuals get Sickle Cell Disease and may not survive to reproduce. However, having the genotype AS offers protection from malaria. AS individuals have an advantage over AA and SS. Having some S alleles in the population would be helpful. Graphs:

g) Summarize the trend for each genotype (AA, AS, SS) in Simulation 2 and Simulation 3.

In Simulation 2 AA genotypes increased in frequency while AS genotypes decreased. SS individuals did not survive.

In Simulation 3 AA genotypes initially went up, but then declined slightly from the starting amount. AS genotypes went up steadily. SS individuals did not survive.

h) Do you think the trends will continue for Simulation 3? Explain why or why not.

Based on the data from simulation 3 and what we know about Sickle Cell Disease and malaria, it seems likely that the allele frequency of the S allele will stabilize somewhere between 30 and 50%, which is higher than the frequency of S alleles in the population without malaria (Simulation 2). Having too many S alleles would result in more individuals getting SS and having Sickle Cell Disease, but having too few would mean more susceptibility to malaria.

Look back at the predictions you made about what would happen in the demo. Were your hypotheses supported or not supported by the data? Explain.

Answers will vary. Gene Pool Name: ______Period: ____ How will the frequency of alleles Evolution Tool: Malaria and Sickle Cell Disease Demo change in the population over time?

Malaria is present in the Variation Interactions between environment What differences are there variation and ecology: between individuals in the What changes have Ecology population? Identify heritable occurred in the 75% A What factors affect the traits that impact survival. population? 25% S survival and reproduction 1 Time of individuals in the Individuals with AA population? (selective AA genotypes do not get forces) (normal SCD, but they are hemoglobin) susceptible to malaria Sickle Cell

Disease Time 2 Time

Malaria Time 3 Time

Malaria is not present Interactions between in the environment variation and ecology: Variation 75% A

25% S 1 Time

Ecology Time 2 Time

Malaria Time 3 Time Explain the evolution of Sickle Cell Disease using the Evolution Three Questions:

Variation: What differences are there among individuals in the population?

Ecology: What factors affect the survival and reproduction of individuals in the population?

Interactions between Variations and Ecology: What changes have occurred in the population? (over time or in different areas) Gene Pool Name: ______KEY______Period: ____ How will the frequency of alleles Evolution Tool: Malaria and Sickle Cell Disease Demo change in the population over time?

Malaria is present in the Variation Interactions between environment What differences are there variation and ecology: between individuals in the What changes have Ecology population? Identify heritable occurred in the 50% A What factors affect the traits that impact survival. population? 50% S survival and reproduction 1 Time of individuals in the Individuals with AA population? (selective AA genotypes do not get forces) (normal SCD, but they are hemoglobin) susceptible to malaria Sickle Cell 68% A Disease AS Individuals with AS

32% S 2 Time (Sickle Cell Trait genotypes do not have SCD symptoms and they / Carrier) are resistant to malaria Malaria SS Individuals with SS 61% A genotypes have SCD and

(Sickle Cell may not survive to 39% S Time 3 Time Disease) reproduce

Malaria is not present Interactions between in the environment variation and ecology: Variation 50% A

50% S 1 Time Ecology AA Individuals with AA (normal genotypes do not get SCD Sickle Cell hemoglobin) Disease 70% A AS Individuals with AS 30% S 2 Time (Sickle Cell Trait genotypes do not have SCD symptoms / Carrier)

SS Individuals with SS 81% A genotypes have SCD and (Sickle Cell may not survive to

19% S 3 Time Disease) reproduce Explain the evolution of Sickle Cell Disease using the Evolution Three Questions:

Variation: What differences are there among individuals in the population?

Ecology: What factors affect the survival and reproduction of individuals in the population?

Interactions between Variations and Ecology: What changes have occurred in the population? (over time or in different areas)

Answer should include:

Variation: AA, AS, and SS genotypes

Ecology: Malaria and Sickle Cell Disease limit the ability of individuals to survive and reproduce. In regions with malaria, AS individuals have an advantage due to resistance to malaria. In areas without malaria both AA and AS individuals survive and outcompete individuals with SS genotypes.

Interactions: In areas with malaria there will be a higher frequency of S alleles in the population since having the genotype AS offers a survival advantage. In areas without malaria there is no benefit to the S allele and those with the genotype SS will suffer from Sickle Cell Disease. For this reason, there will be a low frequency of S alleles in the population.

Name: Evolution Unit

Rules from SCD: What have we learned about how populations change?

SEP: Constructing Explanations CCC: Patterns Cause and Effect

Variation

Ecology: Reproduction

Ecology: Competition

Ecology: Differential Reproductive Success

Interactions between variations and ecology lead to…

Change in population over time

Name: Why don’t antibiotics work like they used to?

Rules from bacteria: What have we learned about how populations change?

SEP: Constructing Explanations CCC: Patterns Cause and Effect

Variation Individuals have the genotypes AA, AS, or SS for hemoglobin. Those who are AA have normal hemoglobin, AS have Sickle Cell Trait and don’t typically show symptoms (except under oxygen stress), and SS have Sickle Cell Disease and experience symptoms that may result in premature death without treatment. This is a heritable trait determined by DNA.

Ecology: Humans reproduce through sexual reproduction (meiosis and fertilization). Each Reproduction parent passes on 1 of their 2 alleles for each gene.

Ecology: Humans compete for food, water, shelter, and space just like other organisms. Competition

Ecology: When malaria is present in the environment, individuals with the genotype AS are Differential best able to survive. When malaria is not present, AA individuals also survive (and Reproductive there is no advantage to the S allele). SS individuals suffer from Sickle Cell Success Disease and may not survive to reproduce. Those best able to survive and compete for resources will reproduce and pass on their DNA.

Interactions between variations and ecology lead to…

Change in In environments with malaria, the S alleles offers an advantage to those with the population over genotype AS, so the S allele will survive in the population at a medium-low time frequency. In environments without malaria there is no advantage to having the S allele and its frequency will be low.

Sean Carroll Evolution Lecture Guided Notes – Endless Forms Most Beautiful Watch the lecture: https://www.youtube.com/watch?v=g6tROZ2hLE8

1. What was Darwin’s academic life when he was young?

2. What are two geological concepts that Darwin used to mold his understanding of biology?

3. What was Darwin’s first great theory about Coral Reef?

4. What were a couple of discoveries that interested Darwin as he explored South America?

5. What were some of the organisms that interested Darwin on the Galapagos Islands (~19min)?

6. How did these observations combine with his knowledge of geology?

7. Why did Darwin hide his research on species formation?

8. How did Darwin’s breeding of pigeons aid in his analysis of the finches?

9. What does the model “life as a tree” suggest about where all different species come from?

10. What is “descent with modification” (~31min)?

11. What did Darwin mean by the broken branches “filled the Earth”? What are some examples? 12. What were the four main ideas from the fossil record?

13. How did species change over time according to Darwin?

14. What are the three ingredients of evolution?

15. What is the genetic variation of the rock pocket mouse?

16. Why does this variation make a difference in survival or the rock pocket mouse?

17. What leads to the black coloration? Is it common in mice (~45min)?

18. How can an allele spread quickly through a population?

19. Summarize the concept of natural selection and its effect on populations.

20. How do mutations arise?

21. Why are homozygous dominant mice slightly different than heterozygous mice?

22. Summarize your ideas about evolution by natural selection from this lecture.

23. What are two questions you have about evolution by natural selection?

Name: ______Period: ______Date: ______

Comparing Evolution Models

Scientists often compare models and evaluate the strengths and weaknesses of each. We have spent some time developing a model for how Sickle Cell Disease evolves in environments with and without malaria. It is time to compare our model to that of two scientists who came before us-Charles Darwin and Jean Baptiste de Lamarck.

Procedure: Get out your “Rules We Learned” worksheet for comparison. Then read the article on the next page summarizing Darwin and Lamarck’s theories and complete the two columns below.

Lamarck’s Theory Darwin’s Theory

Variation

Ecology: Reproduction

Ecology: Competition

Ecology: Differential Reproductive Success

Change in population over time

These materials were developed with funding through a grant from the Gordon and Betty This work is licensed under a Creative Commons Attribution Moore Foundation to Northwestern University and the University of Colorado Boulder. 4.0 License: http://creativecommons.org/licenses/by/4.0/ 1

Two Other Models: Jean Baptiste de Lamarck’s vs. Charles Darwin’s

Jean Baptiste de Lamarck (1744-1829) and Charles Darwin (1809-1882) both developed theories over their careers. They both had theories to explain the variation of life on Earth. Their theories had similarities and differences. Both Darwin and Lamarck believed that life on Earth changed over time and was still changing. They both believed that populations adapted become more suited for survival in their environments and that life on Earth started with fewer, more simple organisms and has developed into many more complex organisms.

Lamarck published his theory to explain the similarities and differences of life on Earth in the book, Theory of Inheritance of Acquired Characteristics in 1801. In this, Lamarck said that if an organism changes during its lifetime in order to adapt to its environment, those changes are then passed on to its offspring. He said that change is driven by what organisms want or need. For example, Lamarck believed that elephants all used to have short trunks. When there was no food or water that they could reach with their short trunks, some elephants stretched their trunks to reach the water and branches. Then because they now had developed a little bit longer trunk through stretching than other elephants, their offspring would inherit long trunks. Lamarck also said that body parts that are not being used, such as the human appendix and little toes are gradually disappearing. He claimed that eventually, people will be born without these parts.

Darwin, on the other hand, published his theory in On the Origin of Species in 1859. In his theory, he said that the desires of animals have nothing to do with how they evolve, and that changes in an organism during its lifetime do not affect the traits it passes on to its offspring, and do not affect the evolution of a species. He said that organisms, even of the same species, are all different and that some will happen to have heritable variations that give them a competitive advantage in their environments to survive more often and have more offspring. The offspring then are born with these trait variations that give them a competitive advantage for survival and reproduction. As more and more of them survive and reproduce, individuals with that trait makeup more and more of the population. Other individuals, that are not so well adapted to this environment, die off. Most elephants used to have short trunks, but some few had longer trunks. When there was no food or water that they could reach with their short trunks, the ones with short trunks died off, and the ones with long trunks survived and reproduced. Eventually, most of the elephants alive today have long trunks.

Making Sense: Which model is more similar to ours (Lamarck’s or Darwin’s)? Explain.

______

Name: ______Period: ______Date: ______

Comparing Evolution Models

Scientists often compare models and evaluate the strengths and weaknesses of each. We have spent some time developing a model for how bacteria populations have changed over time to become more resistant to antibiotics and it is time to compare our model to that of two scientists before- Charles Darwin and Jean Baptiste de Lamarck.

Procedure: Complete the first column of the table filling in each of the rules we developed from bacteria. Then, read the article on the next page summarizing Darwin and Lamarck’s theories and complete the other two columns.

Our Model Lamarck’s Theory Darwin’s Theory

Variation Elephants have short and Elephants have short and long trunks. long trunks.

Ecology: Individual elephants stretch Some elephants are born Reproduction their trunks over their lifetime, with longer trunks (heritable making them longer. They trait). pass on these longer trunks to their offspring.

Ecology: Elephants compete for Elephants compete for Competition resources such as food, resources such as food, water, shelter, and space. water, shelter, and space.

Ecology: The elephants with longer The elephants with longer trunks were better able to trunks were better able to Differential Reproductive reach resources such as food reach resources such as food Success and water. They survive and and water. They survive and reproduce more than reproduce more than elephants with shorter trunks. elephants with shorter trunks.

Change in population over If there is an advantage to If there is an advantage to time having a longer trunk, over having a longer trunk, over time the percentage of time the percentage of elephants with longer trunks elephants with longer trunks in the population will in the population will increase. increase.

Two Other Models: Jean Baptiste de Lamarck’s vs. Charles Darwin’s

Making Sense: Which model is more similar to ours (Lamarck’s or Darwin’s )? Explain.

______Darwin’s model is more similar to ours because he said that evolution acts on existing variation in the population which is produced by heritable traits. Individuals do not pass on acquired traits. ______

______

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How to use this PowerPoint • Work at your own pace. Your health and your family come first. • If possible, you might find it helpful to go through activities at the same time as a peer. Then you can communicate through text, email, or a call if you have questions or to share ideas. • You might find it helpful to have a piece of scrap paper and a pencil or pen to record questions 4 Human Evolution or ideas. • Read through the slides one at a time. Take your time to explore the images and any links. How did humans evolve? • If you come across something you don’t understand, make a note of which slide you are on and come back to it after you go through the whole PowerPoint. If you are still confused, feel free to email your teacher with a question. You could also ask someone in your household or reach out to a peer through text, email, or a call. • When you finish, consider sharing what you learned with someone in your household or a friend through text, email, or a call. Explaining your thinking will help you to retain and make sense of the information.

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Video: Goals Ancient Human Ancestors: Walking in the Woods

After reviewing this PowerPoint, you should be able to: Make a T-chart for notes: 1)Describe what you learned from a video about the What I notice: What I wonder: evolution of bipedalism. • • 2)Describe an aspect of human evolution (closely related • • species, changes in anatomy, and/or how climate change • • impacted human evolution). • •

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Resources from Biology Activity 1 – Our Family Tree for a Changing World © Human Evolution Activities

Choose at least 2 of the activities to explore and complete: Activity 1 – Our Family Tree Activity 2 – Bipedalism Activity 3 – Climate Change and Human Evolution Activity 4 – Hominin Species DNA similarities between species

Follow the directions and answer the questions on the provided Millionsyearsago of worksheet. Additional resources are provided on the slides that follow.

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Activity 2 - Bipedalism

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Activity 3 – Climate Change and Human Evolution Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution- timeline-interactive

Activity 4 – Hominin Species Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution- timeline-interactive

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Check Your Understanding

1)Describe what you learned from a video about the evolution of bipedalism. 2)Describe an aspect of human evolution (closely related species, changes in anatomy, and/or how climate change impacted human evolution). What’s Next? 1) Make a new entry in your Learning Tracking Tool titled “4 Human Evolution.” 2) Consider exploring the videos and interactives from PBS’s series Your Inner Fish

3 What Was "Lucy"? Fast Facts on an Early Human Ancestor By National Geographic Staff PUBLISHED SEPTEMBER 20, 2006

Perhaps the world's most famous early human ancestor, the 3.2- million-year-old ape "Lucy" was the first Australopithecus afarensis skeleton ever found, though her remains are only about 40 percent complete (photo of Lucy's bones).

Discovered in 1974 by paleontologist Donald C. Johanson in Hadar, Ethiopia, A. afarensis was for about 20 years the earliest known human ancestor species.

WHAT DID LUCY LOOK LIKE? With a mixture of ape and human features—including long dangling arms but pelvic, spine, foot, and leg bones suited to walking upright—slender Lucy stood three and a half feet (107 centimeters) tall. Recreations based on other A. afarensis skulls later found nearby reveal an apelike head with a low and heavy forehead, widely curving cheekbones, and a jutting jaw—as well as a brain about the size of a chimpanzee's.

WHY WAS LUCY NAMED LUCY? Inspired by repeated playings of "Lucy in the Sky With Diamonds" at a celebratory party on the day the specimen was found, researchers gave it the Beatles' mod moniker.

HOW DO WE KNOW LUCY WAS FEMALE? Lucy's size gives her away as a female. Later fossil discoveries established that A. afarensismales were quite a bit larger than females.

WAS LUCY AN ADULT? A number of factors point to Lucy being fully grown. For one thing, her wisdom teeth, which were very humanlike, were exposed and appear to have been in use for a while before her death. In addition, the sections of her skull—separated in children—had grown together. Name: ______Period: ______Human Evolution Activities

Activity 1 – Our Family Tree 1. How closely related are you to other primates: a chimpanzee, an orangutan, an Old World Monkey, and a prosimian? What does DNA evidence indicate about relatedness?

2. Two populations are considered separate species when they no longer interbreed (reproduce). Consider what you have learned about evolution. How would primate species evolve over time?

3. What group/genus are modern humans a part of? (Hint: Our species name is ______sapiens.)

4. What are the names of the other groups of hominids in the human family tree?

Activity 2 – Bipedalism 4. How did hominids change as they became bipedal? a. spine

b. pelvis/hips

c. limbs (arms and legs)

Activity 3 – Climate Change and Human Evolution Go to the Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive Click on the “Climate Fluctuations” section. This should pop up some purple bars at the top. Click on these to learn more about climate fluctuations over the course of human evolution. 5. Summarize for yourself: How has the climate changed and fluctuated over the past 8 million years?

Click on the blue “Major milestones in human evolution” circles at the bottom. 6. Identify several adaptions of human ancestors to their environment. How did they survive?

Activity 4 – Hominin Species Go to the Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive Click on the red bars in the species section.

Species Where did it live? When did it live? Notes (What are some interesting facts about this species?)

africanus Australopithecus

anthropus boiseianthropus Australopithecus/Par

Homo Homo erectus

neanderthalensis Homo Homo

Name: ______Key______Period: ______Human Evolution Stations

Station 1 – Our Family Tree 1. How closely related are you to other primates: a chimpanzee, an orangutan, an Old World Monkey, and a prosimian? What does DNA evidence indicate about relatedness? Humans are most closely related to chimpanzees. We are next most closely related to an orangutan, Old World Monkey, and most distantly to a prosimian. The DNA evidence shows that our DNA is 98.2% similar to a chimpanzee and 96.3% similar to an orangutan. This supports the idea that we are more closely related to chimpanzees.

2. Two populations are considered separate species when they no longer interbreed (reproduce). Consider what you have learned about evolution. How would primate species evolve over time? Over time primates would have mutations that created variations. These variations might have helped primates to survive in different locations or to use different types of resources such as eating different foods. This could result in two different populations. Over generations those populations will become more and more different.

3. What group/genus are modern humans a part of? (Hint: Our species name is ______sapiens.) Homo

4. What are the names of the other groups of hominids in the human family tree? Paranthropus, Australopithecus, Ardipithecus

Station 2 – Bipedalism 4. How did hominids change as they became bipedal? a. spine Became “S”-shaped, skull/spine connection moved forward on the skull

b. pelvis/hips Changed from long and narrow to bowl-shaped

c. limbs (arms and legs) The arms changed from being longer than the legs to being shorter than the legs. The angle of the femur changed from angling out to angling in.

Station 3 – Climate Change and Human Evolution Go to the Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive Click on the “Climate Fluctuations” section. This should pop up some purple bars at the top. Click on these to learn more about climate fluctuations over the course of human evolution. 5. Summarize for yourself: How has the climate changed and fluctuated over the past 8 million years? Overall the climate has cooled over the past 8 million years. Climate fluctuations increased about 6 million years ago. There were wet and dry periods and changes in vegetation. Our brain size increased the most during the period of greatest fluctuation.

Click on the blue “Major milestones in human evolution” circles at the bottom. 6. Identify several adaptions of human ancestors to their environment. How did they survive? Humans became bipedal and increased in brain size. We also learned to use tools, fire, and agriculture. These adaptations helped our species to survive changes in climate.

Station 4 – Hominin Species Go to the Human Evolution Timeline at humanorigins.si.edu/evidence/human-evolution-timeline-interactive Click on the red bars in the species section.

Species Where did it live? When did it live? Notes (What are some interesting facts about this species?) Southern Africa (South About 3.3 to 2.1 Au. africanus was anatomically similar to Au. Afarensis

(“Lucy”) with a combination of human-like and ape-like Africa) million years ago features. Compared to Au. afarensis, Au. africanus had a rounder cranium housing a larger brain and smaller teeth, but it also had some ape-like features including relatively long arms and a strongly sloping face that juts out from underneath the braincase with a pronounced jaw. Like

Au. afarensis, the pelvis, femur (upper leg), and foot bones of Au. africanus indicate that it walked bipedally, but its shoulder and hand bones indicate they were also adapted for climbing. Australopithecus africanus Australopithecus Eastern Africa About 2.3 to 1.2 Like other members of the Paranthropus genus, P. boisei is characterized by a specialized skull with adaptations for (Ethiopia, Kenya, million years ago heavy chewing. A strong sagittal crest on the midline of Tanzania, Malawi)

the top of the skull anchored the temporalis muscles (large chewing muscles) from the top and side of the braincase to the lower jaw, and thus moved the massive jaw up and down. The force was focused on the large

cheek teeth (molars and premolars). Flaring cheekbones gave P. boisei a very wide and dish-shaped face, creating a larger opening for bigger jaw muscles to pass through and support massive cheek teeth four times the size of a modern human’s. This species had even larger cheek

teeth than P. robustus, a flatter, bigger-brained skull than P. aethiopicus, and the thickest dental enamel of any known early human. Cranial capacity in this species suggests a slight rise in brain size (about 100 cc in 1 million years) independent of brain enlargement in the genus

Australopithecus/Paranthropus boisei Australopithecus/Paranthropus Homo.

Homo neanderthalensis Homo erectus Indonesia) East Asia (China and Republic of Georgia); Western Asia ( Southern Africa; Northern, Eastern, and t Europeand Southwest o Central Asia

Dmanisi,

40,000 years ago About 400,000 years ago million and 143,000 Between about 1.89

comprise classicthe examples of this species. Generally and China (‘Peking Man’, beginning in the 1920s) Early fossil discoveries from technology. handaxes, the first major innovation in stone tool the fossil record is often associated with theearliest and weak individuals. Theappearance of ape. There that hegrew upat agrowth ratesimilar to that ofagreat million years old. almost all thehand and foot bones), dated around 1.6 ‘Turkana Boy’ completefossil individual of this species i braincase relativeto thesize oftheface. Themost Compared with earlier fossil humans, note the expanded with the ability walk to and possibly run long distances. indicating t consideredare adaptations to alife lived on the ground, arms compared theto size of the torso. These features proportions with humans called Early African origins research. Genome Project is oneof theexciting new areas of human Neanderthal fossils, all from Europe; the Neanderthal DNA has been recovered from more th symbolic behavior. species, had ever practiced this sophisticated and as flowers. No other primates, and no earlier human occasionally even marked theirgraves with offerings, such Neandert or ornamental objects. Thereis evidence that and also ate plant foods, and occasionally madesymbolic and woreclothing, were skilled hunters oflarge animals sophisticated tools, controlled fire,lived in shelters, made Neanderthals made and often larger environments. But their brains werejust as largeas ours stockier than ours, another adaptation toliving in cold warming cold, dry air. Their bodies wereshorter and cheek bones, and a hugenose for humi skulls includethe large middle part of theface, angled extinct human relative. Somedefining features of their Neanderthals (the ‘th’ pronounced as ‘t’) areour closest long as our own species, longest lived early human species not certain highly variable expanded beyond Africa, considered haveto been the first species haveto

Homo ergaster)

to haveto possessed modern human hals deliberately buried their dead and

heloss ofearlier tree is fossil evidence that this species cared for old whether it reached Europe), and possibly the

Homo erectus – species, spread over continentstwo (it's

a well

relatively elongated legs and shorter

proportional to their brawnier bodies. Microscopic study of the teeth indicates

and used adiverseset of -

preserved skeleton (though minus are theoldest known Homo sapiens Homo erectus

fossils (sometimes

Java (beginning in the 1890s) - climbing adaptations, -

about ninetimes as an a dozen , has been around! difying and

is considered a s known as the Homo erectus - like body

early in

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How to use this PowerPoint • Work at your own pace. Your health and your family come first. • If possible, you might find it helpful to go through activities at the same time as a peer. Then 5.1 Introduction to the Evolution you can communicate through text, email, or a call if you have questions or to share ideas. • You might find it helpful to have a piece of scrap paper and a pencil or pen to record questions of Human Skin Pigmentation or ideas. • Read through the slides one at a time. Take your time to explore the images and any links. How can we explain the patterns of human skin • If you come across something you don’t understand, make a note of which slide you are on and pigmentation seen around the world using what we come back to it after you go through the whole PowerPoint. If you are still confused, feel free know about evolution? to email your teacher with a question. You could also ask someone in your household or reach out to a peer through text, email, or a call. • When you finish, consider sharing what you learned with someone in your household or a friend through text, email, or a call. Explaining your thinking will help you to retain and make sense of the information.

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Video: Biology of Skin Pigmentation Goals

After reviewing this PowerPoint, you should be able to: Make a T-chart for notes: 1)Identify several things that you notice from a video and What I notice: What I wonder: several questions that you have about the evolution of • • human skin pigmentation. • • 2)Describe how pigment molecules are produced in the skin. • • 3)Why are folate and vitamin D important? • • 4)Describe how skin pigmentation is related to levels of UV light in a region.

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Use the Intense UV light destroys folate following infographics to answer the questions on the provided worksheet.

Evolution of Skin Pigmentation Infographics from Biology for a Changing World ©

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Vitamin D is produced in skin exposed to UV

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Check Your Understanding 1)Identify several things that you notice from a video and several questions that you have about the evolution of human skin pigmentation. 2)Describe how pigment molecules are produced in the skin. 3)Why are folate and vitamin D important? 4)Describe how skin pigmentation is related to levels of UV light in a region. What’s Next? 1) Finish the worksheet, if you haven’t already. 2) In Lesson 5.2 you will explain the evolution of human skin pigmentation.

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3 [crickets chirp]

[cymbal plays]

[chime plays]

[music plays]

[JABLONSKI (narrated):] Human brains are gray. Human blood is red. Our bones are off-white. Doesn’t matter where you’re born or to whom. But human skin is different.

[music plays]

Some of us have rich dark brown skin; some of us have pinkish white skin. Most of us are somewhere in between. For the longest time, why this variation exists was a real scientific mystery … that opened the door for some to invest this biological trait with moral value, and then use that to justify the suffering of others.

[elephant trumpets]

But biological traits aren’t good or bad. They’re features that have evolved because they enhance an organism’s odds of surviving and passing on its genes.

[JABLONSKI:] Like other animal traits, the sepia rainbow of human skin color evolved through natural selection. Now, thanks to advances in anthropology and genetics, exactly how and why it did is no longer a mystery.

[music plays]

[background discussion]

[JABLONSKI:] Biological anthropologists like myself spend our lives studying how humans evolved, and why we differ from one another physically.

[music plays]

[JABLONSKI (narrated):] Our skin provides one of the most visible markers of human variability. It’s something that sets us apart from our closest animal relatives. Under their dark fur, chimpanzees have pale skin, and millions of years ago that was probably also the case for the primates that were our common ancestors. So where did humanity’s range of skin colors come from?

From physics we know that the color of any object comes from the wavelengths of light that it reflects back to an observer’s eye. We see leaves as green because they reflect back the wavelengths our eyes see as green, absorbing the wavelengths we see as other colors like blue or red. In humans, different wavelengths of light are reflected or absorbed by a pigment in the top layer of our skin. That pigment’s called melanin. It sits inside what look like tiny grains—the melanosomes—that are produced by cells called melanocytes.

Our individual genetic inheritance determines the type of melanin inside our melanosomes. The reddish-yellow pheomelanin is more abundant in lightly pigmented people. More darkly pigmented people have more of the brown-black eumelanin, and the more eumelanin, the darker the skin.

Melanin also colors human and animal hair, and the feathers of many birds.

[JABLONSKI:] Interestingly, the wavelengths of light that melanin reflects are far less important biologically than the ones it actually absorbs. And of the ones it absorbs, the ones that are the most important are those that we can’t even see.

[music plays]

[JABLONSKI (narrated):] Much of the light given off by the sun is invisible to our eyes. Some of that is what’s called ultraviolet radiation, which is highly energetic. So much so, it can actually penetrate living cells. When it does, it can wreak havoc within them. It can even cause mutations in skin cell DNA. What stands between us and that threat is the melanin in our skin.

[crowd noise]

[ABDEL-MALEK:] Melanin is kind of like a sensor; it’s kind of like a guardian molecule. And its main job is protection.

[JABLONSKI (narrated):] For instance, by forming what are called supranuclear caps and absorbing UV.

[ABDEL-MALEK:] They’re like little parasols around the nucleus. And UV cannot penetrate these to go and attack the DNA.

[JABLONSKI (narrated):] That’s just one of the things molecular biologist Zalfa Abdel-Malek finds remarkable about melanin. Another is the broad range of benefits it provides a diverse collection of species.

[ABDEL-MALEK:] We know that melanin in lower vertebrates is important for regulating body temperature. It can also give animals camouflage. And allows them to recognize other members of the species to propagate the species.

[JABLONSKI (narrated):] In humans, one of melanin’s functions is clearly to protect cells from UV damage. As we evolved, we lost hair and increased melanin production in our skin. So, is there a connection between the intensity of UV radiation and skin color?

[JABLONSKI:] Hi, Tess.

[JABLONSKI (narrated):] I first became fascinated with UV and skin color in the 1990s. [pages turning]

But as I searched for information about the global distribution of solar UV, I discovered the available data was in fact quite spotty.

[paper rustling]

I began casting a wider net and almost by accident found exactly the raw data needed to fix that. It hadn’t been collected by anyone interested in my questions, but rather by NASA.

[rocket engine roars]

[MISSION CONTROL:] Ignition.

And liftoff.

[JABLONSKI (narrated):] In the 1980s, concern about the health risk posed by the depletion of UV- blocking atmospheric ozone led NASA to take millions of UV measurements from space. I asked NASA to send me the data, and then asked my geographer husband, George Chaplin, to try to visualize it.

It turned out to be a bigger request than I’d realized, but he found a way to turn all those data points into a map, … a map that showed for the very first time exactly how UV exposure varies throughout the world.

[CHAPLIN:] This is the map.

[JABLONSKI (narrated):] Most striking was the clear gradient between the equator and the poles, which was interrupted only in places where altitude increased UV exposure …

[CHAPLIN:] This is actually in the Tibetan plateau …

[JABLONSKI (narrated):] … and persistent cloud cover decreased it.

[CHAPLIN:] … the Congo Basin. So it’s full of humidity and moisture, which is blocking the UV.

[JABLONSKI (narrated):] Solar energy is a fundamental attribute of any environment. And it’s a well- established fact that organisms living at different latitudes adapt in some way to their local solar conditions. To see how closely human skin color correlates with UV exposure, I collected skin pigment measurements made by anthropologists studying indigenous peoples.

[JABLONSKI:] For many years, anthropologists have faced the challenge of how to accurately measure skin color. We now use this little device called a reflectometer. Basically, it sends out light of specific colors, and then it measures the amount of light that is reflected back. This tells us what color Tess’s skin is, and we can then compare this to people all over the world.

[JABLONSKI (narrated):] George then created a second map, using measured skin colors and environmental data. It showed UV intensity does indeed predict skin color. Wherever UV is strong, skin is dark, like it is near the equator or at high altitude. At the poles, the skin of indigenous people is almost always lighter. That suggests that variation in human skin melanin production arose as different populations adapted biologically to different solar conditions around the world.

[JABLONSKI:] As we’ve noted, our early ancestors probably had full body hair covering pale skin, just like other primates. So when did the darker shades of human skin begin to evolve?

[sea gulls calling]

[JABLONSKI (narrated):] DNA sequencing has made it possible to find evidence that can help answer that question. Rick Kittles is a geneticist who’s skilled at deciphering such clues.

[KITTLES:] Whenever a species undergoes some form of selection, some form of natural selection, evidence of that selection is found in the genome. And so, as geneticists, we get really excited when we explore the genome for these signatures. One way in which that’s done is by sampling worldwide populations and looking throughout the genome at variation and comparing across populations. And it’s a very exciting process, I feel like a detective when I go through that process.

[music plays]

[JABLONSKI (narrated):] One of the many genes that genetic detectives have linked to human pigmentation is called MC1R. Sampling from around the world indicates there’s a fair amount of variation in the DNA sequence of that gene. But not from every corner of the globe.

[KITTLES:] When we look at MC1R within African populations, we don’t see a lot of diversity. And the particular allele that they have in those African populations is the one that codes for darker skin. MC1R codes for a protein which is involved in the switch from the production of pheomelanin to eumelanin. And we know pheomelanin is the reddish-yellow pigment, and then the eumelanin is the brown-black pigment.

[children talking]

[JABLONSKI (narrated):] The absence of MC1R diversity in African populations indicates that, in that part of the world, there is strong negative selection against any alleles that would alter dark skin. And how long has this allele been fixed in African populations? Other genetic studies have calculated that it has been as much as 1.2 million years. Since our species evolved in equatorial Africa, it’s reasonable to conclude that, by that time, all humans were dark-skinned.

[JABLONSKI:] The fossil record supports what we’ve gleaned from genetic evidence. But here’s where we confront what was, for me, the heart of the mystery.

[JABLONSKI (narrated):] The evolution of dark skin in humans suggests that, under strong UV light, that trait provided a survival advantage. So what exactly was that advantage? It’s certainly true UV damage to skin cell DNA can lead to cancer, and skin cancer can be fatal. For a long time, that seemed the likeliest explanation. Except … [JABLONSKI:] Skin cancer generally develops after a person’s peak reproductive years. For that reason, though it might cut your life short, it’s unlikely to affect your ability to pass on your genes.

[JABLONSKI (narrated):] As I was struggling to conceive of an alternative explanation, I happened to attend a lecture on severe birth defects.

[pages turn]

That talk was about a research project that had found evidence that certain birth defects are far more common among pregnant women with diets deficient in a B vitamin called folate. Only weeks before, I’d come across a paper that described how strong sunlight breaks down folate circulating in skin blood vessels. Here was a direct link between UV radiation, skin color, and reproductive success. It was a small “eureka” moment for me.

In the years since, we’ve learned that folate is not only essential for normal embryonic development, it’s even needed for healthy sperm production in males.

[JABLONSKI:] Folate is biological gold. It is an essential nutrient, and it needs to be protected from UV radiation as it circulates in the blood vessels in the skin. That is what melanin does.

[JABLONSKI (narrated):] I felt I was halfway home on my quest to understand human skin color variation. But a big question remained:

[JABLONSKI:] Why aren’t we all dark skinned?

[JABLONSKI (narrated):] It turns out there’s another side to our relationship with UV light. UV light is not all bad. In fact, the small portion of it known as UVB is critical for the synthesis in our bodies of vitamin D—a process that starts in the skin. Without vitamin D, humans cannot absorb calcium from our diet, to build our bones and for a healthy immune system. Back when all of our ancestors lived close to the equator, there was no problem getting enough UVB through dark skin to make the vitamin D needed. But then some populations started moving north, where the UV striking the Earth’s surface is much weaker.

[JABLONSKI:] In northern latitudes, dark skin makes it hard to produce the vitamin D that human bodies really need.

[JABLONSKI (narrated):] The consequences of vitamin D deficiency include rickets—a bone development disease that can cripple the young. In higher latitudes with less UV, the selective pressure on MC1R that produced dark skin in our ancient ancestors, began to abate.

[KITTLES:] When we look at the early movement out of Africa, when that constraint was relaxed, we then see a plethora of variation.

[JABLONSKI (narrated):] In European and Asian populations, geneticists have discovered greater variation in the MC1R gene, but less variation in several other genes—ones associated with lighter skin types. [KITTLES:] Different environments led to other genes being selected for, and being important, for those populations, in terms of skin color.

[JABLONSKI (narrated):] Selection for light-skin gene variants occurred multiple times in different groups around the world, some of it in just the last 10,000 years. Support for the idea that the UV- vitamin D connection helped drive the evolution of paler skin comes from the fact that indigenous peoples with diets rich in this essential vitamin have dark pigmentation.

[music plays]

[JABLONSKI:] The tension between these two aspects of our biological inheritance—on the one hand, the need to protect ourselves from most ultraviolet radiation, and on the other, the need to use some ultraviolet radiation for our own benefit—these forces drove the evolution of the wonderful variation in human skin color that we see around us today.

[JABLONSKI (narrated):] It’s the legacy of an evolutionary balancing act necessitated by the different environmental conditions people have faced around the globe. The thing is, where once human migrations took many generations, we now move about the planet at the speed of sound. That means increasing numbers of us have pigmentation that’s not a good match with where we live.

[ABDEL-MALEK:] People with fair skin and red hair, your phenotype is telling you, you have a high risk of skin cancer if you’re out in the sun. If you’re a dark-skinned individual, living for example in Scandinavia or in Minnesota, you’re not going to have optimal exposure to UV for optimal vitamin D synthesis and you need to take supplements.

[JABLONSKI:] We now know that we need to make cultural adaptations like these to stay healthy. But that’s not all we’ve learned.

[JABLONSKI (narrated):] With the knowledge we now have about evolution, we also know that skin color is a flexible trait that has changed through time, as various groups of people moved to sunny or less sunny parts of the world. And we know that skin color is inherited independently of other traits, and is not associated with other aspects of a person’s appearance or behavior. Skin color is a product of evolution and should never have been judged as something good or bad. We are a very clever and adaptable species, and we are one under the sun.

[music plays] Name: ______Period: _____

Evolution of Human Skin Pigmentation

Examine the maps and infographics. Use these to help you answer the questions.

1. What is melanin?

2. Why are folate and vitamin D important? What do they do for your body and a developing baby?

3. How would light skin color balance the needs for vitamin D and folate?

4. How would dark skin balance the needs for vitamin D and folate?

5. In what type of environment would you expect to find darker skin? Lighter skin?

Then complete the Evolution Tool. Name: ______Key______Period: _____

Evolution of Human Skin Pigmentation

Examine the maps and infographics. Use these to help you answer the questions.

1. What is melanin?

Melanin is a pigment molecule involved in skin pigmentation as well as hair and eye color.

2. Why are folate and vitamin D important? What do they do for your body and a developing baby?

Vitamin D is involved in absorption of calcium. People who get too little vitamin D develop brittle bones, including a disease known as rickets in children.

Folate is a B-vitamin involved in red and white blood cell development. Folate is especially important for pregnant women. Insufficient folate can result in birth defects of the spine and brain.

3. How would light skin color balance the needs for vitamin D and folate?

Light skin pigment is better able to absorb UV-B rays, so more vitamin D is produced. However, light skin pigmentation does not protect folate, which is destroyed by sunlight.

4. How would dark skin balance the needs for vitamin D and folate?

Dark skin pigment blocks UV-B rays, so individuals are less able to produce vitamin D. Darker pigment protects folate from UV, so less is destroyed.

5. In what type of environment would you expect to find darker skin? Lighter skin?

Darker skin is advantageous in high UV environments. Lighter skin is advantageous is advantageous in environments with low UV.

Then complete the Evolution Tool. Gene Pool Name: ______Period: ____ How will the frequency of alleles Evolution Tool: Human Skin Pigmentation change in the population over time?

High UV (sun) Variation Interactions between environment What differences are there variation and ecology: between individuals in the What changes have population? Identify heritable occurred in the 50% lighter skin Ecology traits that impact survival. population? 50% darker skin

What factors affect the traits? 1 Time survival and reproduction of individuals in the population? Lighter skin (selective forces) pigmentation Skin produces vitamin D when exposed to UV

(sun) 2 Time Medium skin pigmentation

Folate is destroyed by UV (sun) radiation Darker skin

pigmentation Time 3 Time

Low UV environment Interactions between variation and ecology: 50% lighter skin Variation

50% darker skin Time 1 Time Ecology Lighter skin pigmentation Skin produces vitamin D when exposed to UV (sun)

Medium skin 2 Time pigmentation Folate is destroyed by UV (sun) radiation Darker skin

pigmentation Time 3 Time Explain the evolution of human skin pigmentation using the Evolution Three Questions:

Variation: What differences are there among individuals in the population?

Ecology: What factors affect the survival and reproduction of individuals in the population?

Interactions between Variations and Ecology: What changes have occurred in the population? (over time or in different areas) Gene Pool Name: ______Period: ____ How will the frequency of alleles Evolution Tool: Human Skin Pigmentation change in the population over time?

What factors affect the traits? 1 Time survival and reproduction of individuals in the population? Lighter skin High vitamin D (selective forces) pigmentation production, high folate destruction by UV Skin produces vitamin D when 25% lighter skin exposed to UV 75% darker skin Medium-high vitamin D

(sun) 2 Time Medium skin production, medium pigmentation folate destruction by UV These are estimates. The trend is what Folate is matters! destroyed by UV (sun) radiation Sufficient vitamin D 10% lighter skin Darker skin 90% darker skin pigmentation production, low folate destruction by UV 3 Time

Low UV environment Interactions between variation and ecology: 50% lighter skin Variation

50% darker skin Time 1 Time Ecology Lighter skin Sufficient vitamin D pigmentation production, low folate Skin produces destruction by UV vitamin D when exposed to UV 75% lighter skin (sun) 25% darker skin Medium skin Limited vitamin D 2 Time pigmentation production, low folate destruction by UV Folate is destroyed by UV (sun) radiation Very low vitamin D 90% lighter skin Darker skin production, very low pigmentation 10% darker skin folate destruction by UV 3 Time Explain the evolution of human skin pigmentation using the Evolution Three Questions:

Variation: What differences are there among individuals in the population?

Ecology: What factors affect the survival and reproduction of individuals in the population?

Interactions between Variations and Ecology: What changes have occurred in the population? (over time or in different areas)

Answer should include:

Variation: lighter, medium, and darker skin pigmentation based on a combination of genes working together to produce the skin pigment trait

Ecology: UV is needed to produce vitamin D, but UV destroys folate molecules. Both vitamin D and folate are important, particularly for the development of babies. Having too little vitamin D and folate can result in health problems that impact the survival of offspring.

Interaction: Skin pigmentation influences the production of vitamin D and the destruction of folate. In high UV environments individuals with darker skin pigmentation have better protection from folate destruction and produce sufficient vitamin D because of the high amount of UV. In low UV environments individuals with lighter skin are able to produce sufficient vitamin D and there is limited folate destruction due to the low amounts of UV. Individuals with medium skin pigmentation would have the advantage in environments with medium UV levels. 4/28/2020

How to use this PowerPoint • Work at your own pace. Your health and your family come first. • If possible, you might find it helpful to go through activities at the same time as a peer. Then you can communicate through text, email, or a call if you have questions or to share ideas. • You might find it helpful to have a piece of scrap paper and a pencil or pen to record questions 6.1 Explaining Other Examples or ideas. • Read through the slides one at a time. Take your time to explore the images and any links. How did dogs evolve? • If you come across something you don’t understand, make a note of which slide you are on and come back to it after you go through the whole PowerPoint. If you are still confused, feel free to email your teacher with a question. You could also ask someone in your household or reach out to a peer through text, email, or a call. • When you finish, consider sharing what you learned with someone in your household or a friend through text, email, or a call. Explaining your thinking will help you to retain and make sense of the information.

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Goals

After reviewing this PowerPoint, you should be able to: 1)Apply the principles of evolution by natural selection to new scenarios (variation in heritable traits, selective forces Watch this Cosmos video: that impact survival and reproduction, and changes in https://www.youtube.com/watch?v=aQHBmY6LbiA populations over time). 2)Identify more and less correct explanations of evolution. 3)Explain why explanations are more of less correct using your knowledge of evolution by natural selection.

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A family has been learning about Evolution. They are Compare your answer with this key watching an episode of Cosmos, and find out that modern Gray wolves and dogs diverged from an extinct wolf species some 15,000 to 40,000 years ago. How could you explain how wolves and dogs became different species? Here’s what each of them thought: Luis: “Wolves and dogs probably lived separately, so they became more different over time.” David: “They probably lived in different places because wolves and dogs behave differently. Wolves avoid humans and dogs love to be around humans.” Elena: “If some wolves were friendly and helpful to humans, the humans might have fed those wolves and taken care of them.” Mom: “Humans might have bred the friendly wolves. Their offspring would have similar traits to the parents.” Dad: “New species evolve all the time. This is just a natural process of speciation.”

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A group of students are discussing their recent field trip to a local farm. They learned that a population of bacteria live in the soil on a Compare your answer with this key farm. The farmer has been using antibiotics to treat the animals, Sam: “The bacteria mutate in response to the antibiotic exposure. Through mutation, some individuals develop the ability to survive at higher antibiotic concentrations. These individuals gradually exposing the soil bacteria to them through runoff and reproduce while the other bacteria die. Because their offspring inherit the ability to survive at animal waste. higher antibiotic concentrations, the entire population evolves to be more tolerant of antibiotics.” How do bacteria cope with their changing environment? Sam is incorrect in saying that “bacteria mutate in response to antibiotic exposure.” Mutations are random. It is true that individual bacteria with mutations that help that to survive the antibiotic will Sam: “The bacteria mutate in response to the antibiotic exposure. Through mutation, some survive to reproduce. individuals develop the ability to survive at higher antibiotic concentrations. These Casey: “Because of genetic variation, there are already individuals in the population of bacteria that individuals reproduce while the other bacteria die. Because their offspring inherit the can tolerate increased exposure to antibiotics. These individuals survive better than their peers and ability to survive at higher antibiotic concentrations, the entire population evolves to be produce more offspring. Because their offspring inherit the ability to survive at higher antibiotic more tolerant of antibiotics.” concentrations, the entire population evolves to be more tolerant of antibiotics.” Casey: “Because of genetic variation, there are already individuals in the population of Casey is the most correct. Evolution by natural selection acts on existing variation in the population bacteria that can tolerate increased exposure to antibiotics. These individuals survive (which was produced by random mutations and in some organisms sexual reproduction). better than their peers and produce more offspring. Because their offspring inherit the Rory: “All of the bacteria adjust their cell machinery so that they can survive exposure to antibiotics. ability to survive at higher antibiotic concentrations, the entire population evolves to be When the bacteria reproduce, their offspring inherit this adjustment and the entire population more tolerant of antibiotics.” evolves to be more tolerant of antibiotics.” Rory is incorrect in saying that “offspring inherit this adjustment.” He is describing acclimation, Rory: “All of the bacteria adjust their cell machinery so that they can survive exposure to when an individual adjusts to conditions in the environment. An example of acclimation is tanning antibiotics. When the bacteria reproduce, their offspring inherit this adjustment and the when in the sun, but we know that babies don’t inherit a sun tan from their parents. His entire population evolves to be more tolerant of antibiotics.” explanation sounds more like Lamarck than Darwin.

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Check Your Understanding 1) Apply the principles of evolution by natural selection to new scenarios (variation in heritable traits, selective forces that impact survival and reproduction, and changes in populations over time). 2) Identify more and less correct explanations of evolution. 3) Explain why explanations are more of less correct using your knowledge of evolution by natural selection. What’s Next? 1) If these examples were challenging, review Lesson 3.1 and your explanation from 5.2. Reach out to your teacher for additional assistance and resources. 2) If you are interested in learning more, consider exploring: OPTIONAL Introduction to Geologic Time PowerPoint Video – Stated Clearly: Does The Theory of Evolution really matter? PBS Deep Time Interactive HHMI Making of Mass Extinctions interactive timeline Videos – PBS Eons

3 https://www.theverge.com/2017/7/18/15992572/dog-genetics-archaeology-fossils-evolution-domestication-wolves Prehistoric fossils suggest modern dogs evolved from a single population of wolves

By Rachel Becker Jul 18, 2017, 4:43pm EDT This dog cranium was discovered in Germany in 2010, next to Neolithic human remains. The skull is about 4,700 years old. Photo by Amelie Scheu

The dogs of ancient Europe probably looked a lot like the mutts roaming Europe today, new DNA discoveries from dog fossils suggest. In the ongoing debate over how many times dogs were domesticated from wolves, this new study suggests it happened just once.

Dogs are the very first species that humans tamed, but the details surrounding dogs’ origins are a little fuzzy. Now, ancient DNA extracted from two 7,000-year-old and 4,700-year-old dog fossils discovered in Germany offer scientists a glimpse at dog evolution. Modern dogs probably descended from just one population that lived continuously in Europe for millennia, according to the research led by Krishna Veeramah at Stony Brook University.

Our furry friends likely evolved from a population of wolves domesticated sometime between 20,000 and 40,000 years ago. Exactly who domesticated these wolves, when, and how many times, is still a mystery, and scientists don’t agree on the answer. Dogs were probably domesticated by accident, when wolves began trailing ancient hunter-gatherers to snack on their garbage. Docile wolves may have been slipped extra food scraps, the theory goes, so they survived better, and passed on their genes. Eventually, these friendly wolves evolved into dogs. “People want a story that someone picked up a wolf cub and made a dog — but it’s been a much more complex process than that,” Veeramah says…

…Veeramah’s team also extracted DNA from two more dog fossils discovered in Germany over the last 20 years. They re-created a canid family tree by comparing chunks of DNA from these ancient dogs and today’s purebreds, mutts, and wolves. By counting the genetic differences, and estimating how long it would take for those differences to show up, they could roughly date when each of these groups split apart. For wolves and dogs, that was roughly 20,000 to 40,000 years ago. For Eastern and Western dog populations, it was probably between 17,000 and 24,000 years ago… 4/28/2020

How does evolution work over large time scales?

Introduction to Geologic Time

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The largest defined unit of time is the eon. Eons are divided into eras, which are in turn divided into periods, epochs and ages. How do scientists figure out what happened on Earth billions of years ago?

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Fossils form under certain conditions

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Relative dating Absolute (radiometric) dating • Determining the sequence of past events • Some isotopes of elements are not stable • Uses geology and order of rock layers • Radioactive isotopes “decay” to form stable isotopes • Scientists can measure the amount of radioactive isotopes in a sample to determine the absolute age of that sample

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Optional video: PBS Eons “A Brief History of Geologic Time” (12:07) Make a T-chart for notes: What I notice: What I wonder: • • • • • • • •

3 Name: ______Period: ______Evolution Self-Assessment

Reflect on the standards addressed in the Evolution unit. Check which box describes your current understanding: 4 I know this well enough to teach it to someone. 3 I can do this with almost no mistakes. 2 I can do much of this, but I have questions. 1 I can do this, but only with help. 0 I can’t do this, even with help.

Evolution Standards Rating (0-4)

I can describe the variety of traits in a population using numbers and probabilities.

I can evaluate evidence showing how group behavior increases an individual’s and a species’ chances to survive and reproduce.

I can describe how common ancestry and biological evolution are supported by multiple types of scientific evidence.

I can explain how the process of evolution primarily results from four factors: (1) the potential for a species to increase in number, (2) the heritable genetic variation of individuals in a species due to mutation and sexual reproduction, (3) competition for limited resources, and (4) the increase of those organisms that are better able to survive and reproduce in the environment.

I can use numbers to explain that organisms with an advantageous heritable trait tend to increase in proportion to organisms lacking this trait.

I can explain how natural selection leads to adaptation of populations.

I can explain how changes in environmental conditions may result in (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species.

Notes / Comments: Name: ______Class: ______KEY Learning Tracking Tool for Evolution: How does the environment impact species over time? How will species change or adapt?

time. Evolution is a scientific theory, environment. How do species which is an explanation for what we In environments where malaria is evolve? see in the natural world that can be present, having the sickle cell allele S is tested and verified. Evidence for an advantage. evolution includes comparative anatomy, embryology, fossils, DNA, and the geographic distribution of species. There is a connection between 1 Evolution Initial Ideas Initial Evolution 1 malaria and Sickle Cell Disease. Having one S allele gives resistance to malaria.

We examined data that shows that in Students MIGHT say: Many options!

environments with malaria the Malaria in the environment impacts the Example: frequency of the S allele is higher evolution of the A and S alleles in What is natural than in environments without malaria. human populations. selection? This makes sense because having the genotype AS makes a person resistant to malaria, so there is an

advantage to having the S allele. 2.1 and 2.2 Malaria and SCD and Malaria 2.2 2.1 and

Evolution acts on variation in Students MIGHT say: Many options! heritable traits in the population. Individuals don’t evolve, populations Example: Individuals compete for resources evolve. Evolution by natural selection How did humans and only some survive to reproduce. works on variation in the heritable traits evolve? This interaction between variation of a population based on which traits and the environment results in help individuals to outcompete others changes in the population over time and to survive and reproduce. (evolution). Charles Darwin’s theory of evolution by natural selection matches our

findings. Lamarck incorrectly thought and Comparing Models Comparing and that individuals would pass on 3.1 and 3.2 Rules We Learned Learned We Rules 3.2 3.1 and acquired traits to their offspring. Humans (Homo sapiens) are Students MIGHT say: Many options! primates. Our closest living relative Humans have different adaptations from Example: is the chimpanzee. All other other primates including walking on two How can we explain hominins (human-like primates) have legs and large brains. These variations in the gone extinct, including the other adaptations enabled us to access human population? species in our genus Homo. different resources and to spread

Hominins are unique because of the across the world. evolution of bipedalism, walking on two legs. This required changes in our anatomy, including the spine and

4 Human Evolution Human 4 hips. Humans have large brained which have enabled us to be flexible and to survive changes in climate.

There are patterns of lighter and Students MIGHT say: Many options!

darker skin pigmentation across the Human skin pigmentation varies based Example: globe. These patterns coincide with on UV conditions in the environment. In How did other species the amount of UV radiation in those places with high UV, darker skin evolve? regions, with lighter skin pigmentation balances the need for pigmentation in areas with low UV vitamin D with protection from folate and darker in areas with high UV. destruction. In places with low UV, This occurs because UV radiation is lighter skin pigmentation allows for needed to produce vitamin D, but UV vitamin D production and folate

destroys folate. destruction is low. 5.1 and 5.2 Skin Pigmentation Skin 5.2 5.1 and