The Evolution Lab 102

The Evolution Lab MISSION 4 MISSION 4 Biogeography: Where Life Lives Introductory video: Life does not stay in one place. Organisms spread out and move around. Plant seeds and fungal spores are carried by the wind and animals cover great distances in search of food. And bacteria? Well, bacteria are just everywhere. But it isn’t just organisms that move—the planet’s tectonic plates move, too. The goal of biogeography is to piece together all of these movements to discover and explain the past and present distribution of life on Earth. It’s a big puzzle with as many moving pieces as there are species that have ever lived. Before you start the first level in this mission, “Saving Hawaiian treasure,” watch the introductory video and answer Questions 1– 4 below. 1. How do organisms come to live on newly formed volcanic islands? They are carried by wine or water from nearby land. 2. The Galápagos finches are an example of an array of species that: a. b. c. d. Migrated to an island as a group Evolved from a single island species Interbred to form one new island species Each independently migrated to an island 3. What is Pangaea? a. b. c. d. An island in Hawaii An ancient supercontinent A species of Hawaiian honeycreeper An ancient common ancestor of birds 4. Explain how a close relative of an African plant came to be living in the tropical Pacific. Saving Hawaiian treasure: You have more than likely heard about the famous Galápagos finches and how they help to illustrate a common pattern in evolution. You may not be as familiar with the honeycreepers of Hawaii, but their story is remarkably similar. In this level, you will again use DNA evidence to piece together a phylogenetic tree. Remember to use the outgroup to help you. Be careful, because from now on, you won’t need to use all of the traits provided. Answer questions 5–8 below before you move on to the next level, “Cone rangers.” Populations of the species ancestors split up and ended up on different landmasses as the continents broke. 5. The common ancestor of the Po’ouli and common rosefinch most likely had: a. An A at position 1 The Evolution Lab MISSION 4 b. An A at position 16 c. A C at position 4 d. A T at position 2 6. When and how do scientists think that the common rosefinch came from Asia to Hawaii? Scientists think that the rosefinch came to Asia to Hawaii between 6-7 million years ago. This happened due to a storm that blew them to the island. 7. There were originally more than 56 species of honeycreeper on the Hawaiian Islands. Today, there are just 18, and many are critically endangered, like the Po’ouli. What most likely happened to the other 38 species of honeycreeper? a. They went extinct. b. They migrated back to Asia. c. They evolved camouflage and we cannot find them. d. They evolved to live underground and we cannot find them. 8. Geologists think that the Hawaiian Islands formed as the Pacific plate moved over a hotspot in Earth’s crust, where molten rock from the mantle made its way to the surface, as modeled below. VOLCANOES ARE PROGRESSIVELY OLDER NW Ni’ihau Kaua’i (5.6-4.9 Mya ) Lithosphere O’ahu (3.4 Mya Moloka’i (1.8 Mya ) Maui (1.3 Mya SE Hawai’i (0.7-0 Mya PACIFIC PLATE Asthenosphere Motion of Pacific plate drags the plume head Mya = million years ago NOT TO SCALE Would you expect a honeycreeper species that lives only on the island of Hawaii to have evolved before or after a honeycreeper species that lives on the islands of Hawaii, Maui, and Oahu? Explain your answer. A species living only on the island of Hawaii most likely evolved after the one living on multiple islands. Hawaii formed later than Maui and Oahu. The species living on multiple islands evolved on an older island and recently migrated to Hawaii, whereas the one that lives on Hawaii likely evolved on that island. The Evolution Lab MISSION 4 Cone rangers: Before Pangaea, there was Gondwana. Gondwana was a massive continent made up of what are today Africa, the Arabian Peninsula, Antarctica, Australia, India, Madagascar, and South America. Gondwana eventually joined up with another ancient continent, Laurasia, to form Pangaea about 300 million years ago. Pangaea broke up for good about 175 million years ago and, eventually, so did Gondwana. As Gondwana’s landmasses broke away from one another, they carried with them a set of organisms that would face changing conditions as the plates moved across LAURASI Earth’s surface. Could this movement be a key to why similar species live thousands of miles apart? Play the level to find out. The pop-up question at the end of the level says that DNA testing led to the discovery that a tree in South America is genetically similar to one in Australia. In fact, these two trees are more closely related to each other than either one is to any other tree in this level—even trees that are found much closer. Which two trees are they talking about? GONDWAN TRIASSIC 200 million years ago Bois bouchon and Pino hayuelo 9. What does finding A. fibrosa on modern-day Antarctica suggest about that continent’s past climate? It suggests the climate of present-day Antarctica was once warmer. 10. Why did A. fibrosa likely go extinct? They likely went extinct because the land mass drifted south toward the role and the climate got too cold for the species to survive. Kangas, gliders, and snakes, oh my!: When a single species diversifies and forms many different but closely related species, the process is called adaptive radiation. Galápagos finches are the result of adaptive radiation. Adaptive radiations occur as species adapt to slightly different environmental conditions. But what about the reverse, or when very distantly related species come to look similar because they live in similar environments? That is call convergent evolution and it’s the topic of this level. Play the level and answer questions 13–16 below before moving on to The Evolution Lab MISSION 4 11. Representatives from the three major groups of mammals are included on the phylogenetic tree in this level. What are the three groups called, and which animal(s) on the tree belong to each group? The three groups are placental mammals (elephant, flying squirrel), marsupial mammals (kangaroo, sugar glide), and monotreme mammals (platypus). 12. If flying squirrels were brought to Australia, what do you predict would happen? a. b. c. d. They’d compete with sugar gliders for resources. They’d form a symbiotic relationship with sugar gliders. They’d interbreed with sugar gliders and produce offspring. They’d evolve to pouches and become identical to sugar gliders. The Evolution Lab MISSION 5 MISSION 5 Tree of Life and Death Introductory video: Despite the skyscrapers we build, the medicines we make, and the landscapes we dominate, humans are connected to other living things—and we aren’t invincible. In fact, some of smallest things of all can cause us tremendous harm. Thankfully, by understanding how we are connected, we can use our giant brains to help fight back. Before you start the first level in this mission, “Hosting blood flukes for dinner,” watch the introductory video and answer questions 1–3. 1. What is a parasite? a. An organism that can cause disease in another organism b. An organism that gains energy and nutrients from another organism c. An organism that requires another organism to complete its life cycle d. d. All of the above 2. What do you think the narrator means when he says, “The host and the parasite are always in this really intimate dance together? The evolution of one species affects the evolution of the other The Evolution Lab MISSION 5 What is HIV? a. The virus that causes Ebola b. The virus that causes AIDS c. A method of DNA sequencing d. An ancestor of humans and chimps Hosting blood flukes for dinner: Blood flukes are the common name given to parasitic flatworms. Parasites rely on hosts, so it perhaps doesn’t come as any surprise that a blood fluke often stays in lockstep with its host’s evolution— even splitting into new species at the same time as its host. When a parasite and host speciate together, it’s called cophyly. When a host and parasite do not speciate together, it may suggest that the parasite has evolved to rely on a different host. Clues to both patterns are found in the phylogenetic tree that you’ll build in this level. Answer questions 4–7 below before you move on to the next level, “Fatal fangs.” Dawn of a modern pandemic: Viruses are strange, and the more we learn about them, the stranger they seem to get. Considered by many as not quite an “organism” because they can’t reproduce outside of a host or generate their own energy, viruses are everywhere—on every surface and inside every living thing. Contrary to what most people think, however, many viruses are harmless. Some are likely even helpful! HIV, however, is not harmless—at least not to humans. Where did it come from? Figuring that out is your job in this level. Answer questions 11–15 below before you move on to the next mission, “You Evolved, Too.” 3. 4. position 1 2 3 4 5 6 7 8 9 10 11 12 13 Chimp SIV-TAN1 (outgroup) G – – – – – A – – – A Gorilla SIV HIV-1 group M HIV-1 group N T C A – – – – – – – – – – – – – – – A T T – – – – – – – A HIV-1 group P Chimp SIV-MB897 T C – – – – – – – – – – A T – – – – – A Chimp SIV-EK505 A – – – – – T – – – A – A – A – A 14 – – – – – – – – – – – – – – C G G G G G G A Cameroonian woman living in Paris was the first to be diagnosed with HIV-1 P in 2009. Which ape virus is most closely related to HIV-1 P? Gorilla SIV 5. Based on your completed tree, how can you distinguish HIV-1 M from HIV-1 N? a. HIV-1 M has a C at position 1; HIV-1 N has an A. b. HIV-1 M has an A at position 11; HIV-1 N has a G. c. HIV-1 M has a G at position 14; HIV-1 N has a T. The Evolution Lab MISSION 5 d. HIV-1 M has a T at position 7; HIV-1 N has an A. 6. How do scientists think that SIV has jumped hosts to humans? Through the hunting, killing, and eating of illegal ape bushmeat 7. Based on your phylogenetic tree, how many times—at a minimum—do you infer that an HIV virus has jumped hosts to humans? I infer that at least 3 times: once from gorillas, and twice from different populations of chimpanzees 8. Viruses such as HIV reproduce rapidly. What is the connection between reproduction rate and evolution? Mutations occur more frequently when genetic material is replicated which happens when a virus reproduces. The faster a virus reproduces, the more mutations occur. Mutations cause evolution, so the more mutations there are, the more opportunities there are for natural selection. The Evolution Lab MISSION 6 MISSION 6 You Evolved, Too Introductory video: In his 1871 book, Descent of Man, Charles Darwin predicted that evidence would be found in Africa that would link modern man to apes. Finally, in the 1950s, such a discovery was made by Mary and Louis Leakey in what is today Tanzania. Since then, fossil evidence and DNA analyses have piled on the support. Today, there is no doubt as to our close kinship with chimpanzees, with whom we shared an ancestor about 6–7 million years ago. This mission is all about our evolution over those past 6–7 million years. Before you start the first level in this mission, “Planet of the apes,” watch the introductory video and answer questions 1–2 based on your background knowledge. 1. Chimpanzees are: a. b. c. d. Less evolved than humans Direct ancestors of humans The closest living relatives to humans Both a and b 2. Which of the following is a correct statement about human evolution? Humans did not evolve. Humans have evolved and continue to evolve. Humans evolved until about 5 million years ago, but no longer evolve. Humans have evolved and continue to evolve socially, but not biologically. Planet of the apes: You probably don’t have any issue distinguishing a human from a chimpanzee, gorilla, or orangutan. But you might if you were looking at DNA instead of physical traits. The differences you see are caused by a shockingly tiny proportion of our DNA—who knew that just a few Gs, As, Ts, and Cs could do so much? Answer questions 3–5 below before you move on to the next level, “Back to skull.” a. b. c. d. position 1 2 3 4 5 6 7 8 9 10 11 12 13 Chimpanzee – – G – – – – T – T – – G – 14 15 – Gorilla Human – – – – T G – – – – – – – – T A – – T T – – T – – – – Orangutan – – G – – – – T – – – – – GT – – T 16 17 18 19 20 – G – G – G – T – – – – – – – – – – – – 3. This data set shows all of the nucleotide differences in a 500-base sequence. Approximately what percentage of DNA do humans have in common with a chimpanzee? a. 1/500 = 0.2% b. 5/500 = 1% c. 495/500 = 99% The Evolution Lab MISSION 6 d. 499/500 = 99.8% 4. The closest living relatives to orangutans are: a. b. c. d. Chimpanzees Gorillas Humans Chimpanzees, gorillas, and humans equally 5. True or false: “Gorillas are more closely related to chimpanzees and orangutans than they are to humans.” Explain your answer. Gorillas are most equally closely related to chimpanzees and humans. They are more distantly related to orangutans. Back to skull: Animals more closely related to modern humans than to modern chimpanzees are called hominins. All members of the hominin group are extinct except one—us, Homo sapiens. In the not-toodistant past, there were several other Homo species living on Earth; a couple of them lived at the same time as Homo sapiens. There were also many species of our closest extinct cousins, the Australopithecines, and several other hominin species as well. Although rarely even close to complete specimens, hominin fossils have told us a great deal about our extinct relatives. In this level, you’ll explore features of various hominin skulls to learn about some of the things that make us —and other members of our genus Homo—human. Complete the level and answer questions 6–10 below before moving on to the final level, “Inside out of Africa.” 6. According to the completed tree, which of the following traits is shared among all species in the genus Homo, but no others? a. Large braincase b. Midsized braincase c. More upright face d. Smaller canine teeth 7. The first hominin species to spread out of Africa was: a. The chimpanzee b. H. erectus c. H. neanderthalensis d. H. sapiens 8. The date ranges for each of the hominins in this puzzle are given below. Plot them on the timeline given. One has been done for you. The Evolution Lab Species Known Date Range Australopithecus afarensis 3.85–2.95 million years ago Homo erectus MISSION 6 1.89 million years ago–143,000 years ago Homo neanderthalensis 400,000–40,000 years ago Homo sapiens 200,000 years ago–present H. neanderthalensis A. afarensis Homo erectus Homo sapiens Present 1 mya 2 mya 3 mya 4 mya mya= millions of years ago; 0.5 mya = 500,000 years ago 9. At least how many Homo species shared the planet 500,000 years ago? At least 3 10. A common misconception is that humans evolved from chimpanzees. It can therefore be confusing to some people that there are still chimpanzees. How could you use a tree diagram like the one you generated in this level to explain the correct relationship between living chimps and living humans? Humans did not evolve from chimps. Chimps and humans both evolved from a common ancestor. After the split from this common ancestor, many hominin species arose, lived, and went extinct. The Evolution Lab MISSION 6 Inside out of Africa: Most hominin species, including Homo sapiens, arose in Africa. It is sometimes possible to extract DNA from ancient humans (of our species and closest cousins) for analysis. The oldest hominin DNA ever sequenced came from a 400,000-year-old thighbone. Comparisons among ancient remains and populations of humans around the world have yielded insights into when and how various Homo species migrated out of Africa. Answer questions 11–13 below before you move on to the conclusion video. position 1 2 3 4 5 6 7 8 9 10 11 12 13 Dinka G – – – – G – A – – C Italian Khoisan P.N. Guinean G G A – – – – – – – – – – – – G G G – – – G A A – – – – T Yoruba G – – – – G – A – – T – T – T 14 15 G C C T G T C T G C 16 17 18 19 20 – – T – – – – – – T C – – – – – – 21 – – G – – G G G – – A – –T – – – – T – – – – 12. There is significant genetic evidence to suggest that interbreeding occurred between Homo neanderthalensis and which other species? a. Australopithecus afarensis b. Homo erectus c. Homo habilis d. Homo sapiens 13. Yoruba peoples are most closely related to which other population from the phylogenetic tree? a. Dinka b. Italian c. Papua New Guinean d. Dinka and Papua New Guinean equally 14. No fossils of Homo neanderthalensis have been found in Africa, but many African populations have traces of Neanderthal DNA. If Neanderthals were never in Africa (which is a possibility, though fossils may yet be found), how can the presence of Neanderthal DNA be explained? Populations of Homo sapiens which had Neanderthal DNA migrated back to Africa. They then interbred with the population in Africa.