PRISM UHH GK-12 PRISM UHH GK-12 Natural Selection Hawaiian Origami Birds
Summary Concepts After students have a strong understanding of Adaptations and Genetic In 1859, Cha rles Darwin Variation, they will be introduced to Natural Selection. They will participate in and Aflred R ussel a natural selection simulation in which they will create and modify “paper Wallace propos ed the airplanes” over several generations to visualize how favorable heritable traits are theory of evol ution by passed on. These paper airplanes represent wild birds of a population. natural select ion. Their theory was la ter combined with Mendel ian Objectives inheritance to explain the • Students will simulate how genes are passed from one generation to the connection of genes (units next. of evolution) and natural • Students will understand how traits that are favorable for survival selection. Thi s theory has become more common over generations. become the pr inciple • Students will know that both genetic variation and environmental factors explanation f or species causes of evolution and species diversity. diversity. Materials Standards ad dressed Paper 7.5.4, 7.5.6 Ruler Tape Duration Straws 1 60 minute class periods Scissors Coin Source Mate rial Six-sided die w w w.indiana. edu/~ensiw eb/lessons/o rigami.html Background The Hawaiian Origami Bird (Aves hawaiiensis) lives on the rugged coastline of Vocabulary Hawaii Island. It feeds on Opae'ula (Halocaridina rubra) which are found in Natural Selec tion anchialine ponds around the island. Due to high development of the coastline on Phenotype the island, alchialine pools are decreasing and becoming less common. Only Genotype birds that can successfully fly the long distances in search of Opae'ula will live long enough to breed successfully. This simulation will allow students to breed several generations of the Hawaiian Origami Bird to see how phenotypes and genotypes are affected over time. Biological evolution, which is the gradual change to a population of species over many generations, is the process responsible for the diversity of species. Natural selection is the process by which favorable traits that are passed on over generations become more common in a population of reproducing organisms. Natural selection is also responsible for how unfavorable traits (not conducive for survival) become less common in the population. This process acts upon the phenotype or the morphological characteristics of an organism. Organisms that have favorable phenotypes that allow them to survive and reproduce in the wild are more likely to survive than organisms that have unfavorable phenotypes.
If the phenotype is based on genetics, then the genotype associated with that
favorable phenotype will increase in frequency in the next generation and
generations to follow. Natural selection also acts upon populations, not
individuals alone. The changes to the phenotype and genotype must affect the entire populations of organisms, not just select individuals of the population.
Teacher Prep for Activity • Prior to this lesson, the teacher can cut the paper into different sized strips. Be sure to make many strips of each size (they will vary from the original size of 3 cm x 20 cm). The width and circumference of the strips will increase or decrease by 1-2 cm after each generation. • Xerox Origami Data Sheets • The pr ocedure section can be Xeroxed and handed out or the diagrams can be written on the board.
Procedure 1). Split stude nts into groups of two. Each student will prepare an ancestral bird: Cut two strips of paper, each 3 cm x 20 cm. Loop one strip of paper with a 1 cm overlap and tape. Repeat for the other strip. Tape each loop 3 cm from the edge of the straw.
2). Breed off spring. Each Origami Bird lays a clutch of three eggs. Record the dimensions of each chick and hatch the birds using these instructions: a. The fir st egg has no mutations. It is a clone of the parent, this measurement will be the same as the ancestral bird. In the interest of time you may substitute the parent when testing this chick. b. The other two chicks have mutations. For each c hick, flip your coin and throw your die then record the results on the table. i.) The coi n flip determines where the mutation occurs: the head end or tail end of the animal. ii). The die throw determines how the mutations affect the wing:
After you have determined where the mutation occurs, cut new strips of paper and re-build another bird with the new measurements. You can use the strips from the original bird if able. iii). Lethal mutations: A mutation which results in a wing falling off of the straw, or in which the circumference of .the wing kujis skjmkjalkjlerkj tkjhakjn kjthe circumference of the straw, etc. is lethal. Fortunately, Aves hawaiie nsis birds are known to “double clutch” when an egg is lost. If you should get a lethal mutati on, disregard it and breed another chick.
3). Test the b irds: Release the b irds with a gentle, overhand pitch. It is important to release the birds as uniformly as possible. Test each bird twice.
4). The most successful bird is the one that can fly the farthest. Mark which c hick was the most successful on the tally sheet provided.
5). The most successful bird is the sole parent of the next generation. Use the measurements from this bird to be the parent of the next generation. The following generation will be continuing to breed, test, and record data for as many generations a s you can in the time allotted. Use the table to record the results of your coin flips and die throws, the dimensions of all chicks, and the most successful bird in each generation.
Extensions a nd assessment You can use t he following questions for discussion of the topic. These can either be turned in for credit or can be discussed during the next class period.
1. Did your e xperiment result in better flying birds?
2. Evolution i s the result of two processes: variation and selection. a. How did your experiment produce variation among the offspring? b. How did your experiment select offspring to breed the next generation?
3. Compare you r youngest bird with your neighbor’s youngest bird. a. Compare a nd contrast the wings of of other birds with your own. b. Explain why some aspects of the birds are similar. c Explain why some aspects of the birds are different.
4. Predict the appearance of your youngest bird’s descendants if: a. the selection conditions remain the same and the longest flying bird survives to produce the most .offspring. b. the selection conditions change the worst flying bird survives to produce the most offspring. c. the selection conditions change and the bird whose color blends with its environment survives to .pr oduce the most offspring.
5. Predict how the Aves hawaiiensis might adapt after the alchialine pools have disappeared from over development?
Name ______Date ______
Origami Bird Data Sheet
Flip coin, throw die, record results. Plan the baby chicks, record their dimensions, breed the chicks.
GENERATION 0:
No Mutation COIN COIN
3 x 20 3 x 20 ______x ______x _kk
Head k Tail Head Tail Head Tail
DIE DIE
3 cm 3 cm
Mark the winning bird. Only the most successful bird becomes a parent of the next generation. The “no mutation” chick in the next generation is identical to the winning bird in the immediately preceding generation. Continue to flip and throw, plan chicks, breed them, and test them for more generations.
PRISM UHH GK-12 Exploring the Ohia Common Garden Natural Selection Summary Concepts After students have a strong understanding of Adaptations and Genetic Variation, Changes to the they will be introduced to Natural Selection. They will visit the Ohia Common environment may affect Garden in Volcano, Hawaii to see how Ohia (Metrosideros polymorpha) from how an organi sm may different elevations have morphological differences. survive in the wild. Occasionally, organisms Objectives have the ability to activate • Students will simulate how genes are passed from one generation to the different phe notypes in next. response to its changing • Students will understand how traits that are favorable for survival become surroundings . This lesson more common over generations. uses an endemic Hawaiian • Students will know that both genetic variation and environmental factors tree species, Ohia, to show causes of evolution and species diversity. how this spec ies changes its phenotype in response Materials to different ha bitat Background information about Ohia to lecture students before visiting garden requirements . Permission to visit the garden Dr. Elizabeth Stacy-can give presentation at garden about Ohia Standards ad dressed 7.5.4, 7.5.6 Background Biological evolution, which is the gradual change to a population of species over Duration many generations, is the process responsible for the diversity of species. Natural 1 full day for field trip selection is the process by which favorable traits that are passed on over generations become more common in a population of reproducing organisms. Vocabulary Natural selection is also responsible for how unfavorable traits (not conducive for Natural sele ction survival) become less common in the population. This process acts upon the Phenotype phenotype or the morphological characteristics of an organism. Organisms that Genotype have favorable phenotypes that allow them to survive and reproduce in the wild Glabrous are more likely to survive than organisms that have unfavorable phenotypes.
Pubescent If the phenotype is based on genetics, then the genotype associated with that Phenotypic plasticity favorable phenotype will increase in frequency in the next generation and generations to follow. Natural selection also acts upon populations, not Source Mate rial individuals alone. The changes to the phenotype and genotype must affect the PRISM entire populations of organisms, not just select individuals of the population.
Ohia lehua (Metrosideros polymorpha) is a Hawaiian endemic plant found in almost all Hawaiian ecosystems. It is present on all Hawaiian islands, except Niihau and Kahoolawe. Ohia is an extremely variable plant that ranges in elevation from sea level to approximately 7000 feet. In order for Ohia to survive and reproduce at such drastic environments, species at different elevations have morphological differences. Ohia found at low elevations have larger, glabrous (smooth with no hair) leaves while ohia at high elevations have smaller, pubescent (with short fuzzy hair) leaves. One reason ohia at high elevations have smaller, fuzzy leaves is because they are closer to the sun and the fuzzy hair might protect the leaves from cold temperatures. Lower elevation Ohia are further from the sun and need a larger surface area to collect more sunlight and they are without fuzzy hair because they live at warmer temperatures. Ohia have a given phenotype, but also have the ability to change its phenotype in response to environmental changes. This phenomena is called phenotypic plasticity.
Teacher Prep for Activity Weeks prior to the field trip, Dr. Elizabeth Stacy at the University of Hawaii, Hilo must be contacted for access into the common garden. Dr. Stacy could possibly be available to meet with the students to discuss Ohia and natural selection also. Her contact information is: Elizabeth Stacy, Assistant Professor Department of Biology, Uni versity of Hawaii 200 West Kawili Street Hilo, Hawaii 96720, Email: [email protected]. Please give yourself many weeks to months in advance to plan this field trip.
Procedure After finalizi ng the plans to visit the Ohia common garden, give the students some background information on Ohia before vi siting the garden. At the garden, Dr. Stacy will talk about Ohia and its morphological differences. After the lecture, students will be split into groups and be asked to examine the different trees at the garden. They will be asked to collect a single leaf from a tr ee from high elevation, mid elevation and low elevation. After they have collected their leaves, they will be asked to explain why they think the leaves they collected belong to their respective habitats. After the field trip is compl eted, have the students write a reflection about their trip to the garden. They could also be asked to research anot her organism that displays phenotypic plasticity.
Assessment Journal writi ng Written repor t of another organism that displays phenotypic plasticity.
Extensions If the class is unable to visit the common garden or a project extension is needed, a possible class simulation of this exercise would be to grow tomato plants. Before growing the plants, ask the students if they think tomato plants (with t he same genotype) grown in sunlight would look different from tomato plants grown without sunlight. Ha ve them write down their predictions. Plant several plants in pots and place half the plants in direct sunlight and place the other half in the classroom, away from any light. Water and feed both sets of plants the same way. T he plants grown in direct sunlight should grow upright, reaching for the sun while the plants grown inside should grow low, creeping along searching for sunlight. This simulation shows that different environmental factors can a ffect how an organism survives.
NATURAL SI
GOAL Natural Selection introduces students to natural selection as the mechanism that produces change in the genetic makeup of a population.
OBJECTIVES SCIENCE CONTENT Environmental factors put selective pressure on populations. Natural seletion is the process by which the individuals best adapted to their environment tend to survive and pass their traits to subsequent generations. Members of a species are all the same kind of organisms and are different from all other kinds of organisms. CONDUCTING INVESTIGATIONS Use a game simulation to experience change in a population, resulting from selective pressure. Record and process information presented in a video about natural selection. Use a multimedia simulation to explore the effects of natural selection on a population. BUILDING EXPLANATIONS Describe how selective pressure can affect the genetic makeup of a population. Explain how the traits expressed by the members of a population can change naturally over time. SCIENTIFIC AND HISTORICAL BACKGROUND It may be said that natural selection is daily Darwin brought his book to print. The and hourly scrutinizing throughout the world, ideas disseminated quickly throughout the every variation, even the slightest; rejecting scientific community, and in their wake a that which is bad, preserving and adding up all new understanding of the progression of that is good; silently and insensibly working, life emerged. whenever and wherever opportunity offers, at the improver~entofeach organic being in NATURAL SELECTION relation to its organic and inorganic conditions of lqe. The idea is simple, really, and is -Charles Darwin constructed on some fundamental assumptions that have since been shown In 1831,22-year-old Charles Darwin to be sound. embarked on a 5-year voyage of discovery Nature Produces Variation. During the as resident naturalist aboard the survey process of reproduction, random changes ship Beagle. The impact of the incredibly occur in the genetic information directing diverse and complex biota he encountered the manufacture of a new unit-an in South America revolutionized his offspring. Extreme changes are usually perception of life on Earth. During the lethal, and no offspring result. Those voyage and the years following, Darwin genetic miscues are not perpetuated. formulated a theory explaining the Modest changes translate into often subtle uniqueness and origin of the organisms he and sometimes dramatic differences in discovered. It was many years, however, individuals. Individual offspring turn out before he finally published his famous to be unique; one perhaps a little larger, book, On the Origin of Species by Means of another more aggressive, and still others Natural Selection, in 1859. darker in color, slower to respond, having Darwin anguished over his manuscript. larger fins or wider teeth, on and on. The He was diligent in his science, wanting result is variation in populations. solid sources of evidence for his Life Is a Challenge. Many factors sveculative ideas. But even when the I converge to prevent organisms from theory was clearly described and enjoying a peaceful, relaxed, successful supported to hssatisfaction, he feared the existence. The physical environment can societal response to his propositions. The be harsh, and is often variable. Weather assumed affront to God, excused from the and catastrophe put pressure on role of creator of all nature, and the organisms that can stress, weaken, and kill reduced status of humanity, dismissed them. At the same time, nature produces from the pinnacle of creation, troubled many more organisms than can be Darwin. But when he found out that supported by the environment. Alfred Wallace had reached essentially the Organisms that are not adapted to same conclusions about natural selection withstand environmental pressures are and was preparing to publish his work, doomed to fail. Biotic factors put pressure on organisms. The measure of the success of a population Heterotrophc organisms eat other is its ability to withstand change in the organisms for energy and building blocks. environment and to prevail. Nature's Organisms that fail to acquire food die. hedge against complete disaster imposed On the other side of that equation, by disease, drought, or hoards of predators organisms that are taken for food also die. is variation. When a new pressure is Microbes sometimes invade organisms, imposed on a population, some causing disease. Life is always under individuals may succumb. But some will pressure. likely have adaptations that allow them to survive and reproduce more offspring Organisms in a Population Compete. than other individuals of that species. In Every species has a niche in which it lives this way the population continues, but and acquires the resources it needs for changes. survival. The problem is, all the other members of an organism's species are Darwin did not have the benefit of trying to make a living in that niche as understanding the fundamentals of well. This creates competition among genetics, although it was well accepted members of a population for access to that organisms passed the code for making limited resources. If resources are not reasonably accurate reproductions of limited, members of the population could themselves from generation to generation coexist without complications. Those through sexual processes. He was able to individuals that succeed in getting observe firsthand the variation within a resources and that successfully reproduce population, particularly when he observed pass their genes to the next generation. the finches on the Galfipagos Islands. The puzzle that Darwin pursued was how the The measure of the success of an countless kinds of organisms came into individual organism is whether or not it being. What forces created a new kind of survives and reproduces. The traits that organism? What was the origin of species? prepared a successful organism to complete its destiny are passed to the next If a population existed in a constant, generation. Traits that resulted in supportive environment, natural processes successful reproduction by their parents would produce variation in the are, in all likelihood, the traits that will population, and the individuals would all increase the offspring's chances of have reasonable chances of survival. The reproducing. Successful individuals pass success of a varied population would the tools of success to their offspring. perpetuate a varied population. As discussed earlier, however, the Pressure on the population might favor perversity of the physical environment some individuals over others because the and the pressures imposed by the biotic variations represent different adaptations, community don't allow for the idea of a and different adaptations affect the perfect organism, ideally equipped to potential for survival. So selective survive. Survival has to happen in a pressure on a population will favor some dynamic environment, so perfection is a individuals, which will reproduce, resources, and they thrived. As time influencing the distribution of traits in the passed, variation entered the population. individuals. The population changes in The most conspicuous variation was the response to selective pressure. (Notice, beak. Different subgroups within the individuals don't change in response to population were better adapted to exploit selective pressure; they only survive or die. different food sources. We can imagine Populations change depending on the that the members of the population that characteristics of the survivors.) sought similar food sources would associate, and other groups that shared Over time a population may change different traits would associate. Feeding sufficiently for science to judge it to be a behavior isolated subgroups within the different kind of organism than it was larger population. Breeding among the before the selective pressure was brought subgroup reinforced the trait that isolated to bear on the original population. How it in the first place, further separating the long does that take? And how different subgroup. does the "new" population have to be to be deemed a new species? Variation within the subgroup might have produced other traits that also tended to It isn't easy to answer these questions. A isolate the subgroup, perhaps coloration, new species may emerge in an extremely size, nesting habits, mating rituals, and so short time-a matter of days or weeks in forth. In time, isolation and change in the case of bacteria. Or it may take response to pressures from the millions and millions of years for a environment produced a new subspecies. successful species like the white shark or The exact time at which a splinter group is horseshoe crab to change enough to be awarded the status of species is a subject considered a new species. for scientific debate. There are few Darwin observed the finches on the absolutes for defining a species, so the GalApagos Islands. The 20 or so islands moment at which it happens is nebulous. are situated about 1000 km west of Ecuador. The current islands range in age Darwin concluded that speciation was a natural outcome of ongoing life processes: from about 700,000 to 4 million years, but (genetic) variation in a population, scientists suggest that there may have been selective pressure in the environment, and other islands or sea mounts in the area as isolation of a segment of the population. long as 10 million years ago. The point is Darwin's momentous discovery is often that the GalApagos Islands are young, and summarized as "survival of the fittest." any terrestrial life had to make its way This creates a mental image of a ferocious there across the open sea or through the battle for survival, with the biggest, air. strongest, most voracious individuals Some time ago a single finch species always surviving to continue their kind. arrived on the islands. Perhaps a small This is not an accurate picture. Fittest flock was blown off course in a storm. The doesn't necessarily mean the individual in birds apparently had no competitors for the best condition or the one with the biggest teeth and strongest bones. It through millions and millions of handoffs means the individual with the best without a fumble. adaptations to survive the pressure being The processes of variation, natural imposed by the environment. Fittest selection, and isolation have produced an simply means the best equipped to amazing array of organisms. There are survive and reproduce. millions of species alive on Earth today, Who or what determines fitness? The and for each one there were at least a selective pressure in the environment. The hundred species that are now extinct. The pressure might come from the weather. A process of evolution has produced a return of the ice ages will select for those continuous parade of new species, each individuals with adaptations for surviving adapted to the specific environments in cold and select against those without which it lived, and continues to do so adaptations for cold. A new predator that today. climbs trees will select for those tree- dwelling individuals that can flee or defend against the predator, and select ARTIFICIAL SELECTION against those that have no defensive A discussion of artificial selection might adaptations. A drought that reduces the shed light on the selection process. We acorn crop may select for the smaller humans have one adaptation (thanks to members of a population that can survive natural selection) that makes us a on less food and select against those that formidable organism to deal with-an require more food. The result of natural advanced brain. We can control our selection is that the genetic makeup, and environment to an unprecedented degree. therefore the suite of traits expressed by As a result we can manage food resources, the population, is constantly changing. create shelter, manipulate energy, control The change process in organisms is called other organisms, and re-create the world evolution. Organisms can be thought of we live in. as work in progress; they are constantly One human enterprise is manipulating the evolving from something into something traits of organisms through artificial else. selection. Think about the domestic dog. If you follow the evolutionary process Every breed From the skinny, shivering back in time, perhaps 3.5 billion years or Chihuahua to the robust, barrel-toting St. so, logically you eventually arrive at the Bernard, and all the retrievers, hounds, first living organisms on Earth. terriers, poodles, spaniels, bulldogs, collies, Remember, life is the Olympic flame that and Pomeranians in-between are the same burns in every organism. The flame is species. Where did all the diversity come handed from one organism to the next. If from? Variation, selection, and isolation. it goes out, it cannot be rekindled. Life Let's say you wanted to have a dog to has only one chance to carry the torch, and catch squid for you. Where would you get every organism guards it tenaciously as such a dog? Because there is no such dog, long as it can. So every organism alive you would have to breed one. Squid live today has received the precious fire in the water, so you need a dog that is dysfunction, or shvering, shows up as a enthusiastic about water and swims well. trait in the breed, it may be difficult or A retriever or a spaniel would be a good impossible to breed it out without losing breed to start with. So you get a bunch of the traits you selected for in the first place. retrievers and spaniels and show them a A reduced gene pool caused by inbreeding squid. Toss the squid in the water and see often introduces vulnerability and whch dogs jump in to grab it. Of the weakness into the breed, due to lack of original subset of water-loving dogs, only variation. a few will pass the "goes for squid" test. Artificial selection has been used for years Breed the squidophiles and raise the pups. to develop disease-resistant strains of Test them for squidophilia. Breed the most grains, higher-yielding corn, faster- promising of those. maturing soybeans, square tomatoes, Take the best squidders out in a boat and seedless watermelons, and hundreds of see how good they are at spotting a squid other agricultural plants. And, of course, in the water. Breed those with the best horses and livestock are selectively bred night vision. What's the best color (maybe for a variety of functions and products, black) and hair length (shorter the better). and the celebrated silk moth and the large Identify those sharp-eyed squidophiles and exotic goldfish called koi have been that have the darkest, shortest fur. The selectively bred for centuries to produce animals that have the traits that fit your the living products we see today. needs are the ones that you allow to Nahire does the same, but without reproduce to get more offspring with their purpose, allowing some individuals with traits. the right stuff to produce more offspring After many generations of selective than others in the population. But in breeding you produce a squid hound, nature, the selection is based on passing a equal to the task you want it to perform. test, not possessing arbitrarily desirable And if you find you are not completely traits. And the "right stuff" is having the satisfied with the dog's performance in the traits that better prepare the offspring to future (maybe the breed shakes after survive and reproduce, not measuring up getting back into the boat after snaring a to a set of predetermined criteria. squid), you can always continue to tinker You've heard the lament, "Just when I with the traits to make it "better" by learned the answers, they changed all the breeding members of the isolated questions." That's the way it goes out population that have the desirable trait, in there in the biosphere--every time an this case, stand and drip. organism "gets it right," the environment There is danger in this process. By changes the test, so the winner yesterday isolating a small population, you may not have the right stuff to win today. significantly reduce the diversity in the That's natural selection, and that's what gene pool. If a genetic weakness, such as a keeps life evolvkg on Earth. tendency to bite, kidney disease, joint WHY DO I HAVE TO LEARN THIS? This investigation presents some sensitive encourage students to engage them and issues. The ideas of natural selection and incorporate them into their growing evolution of life on Earth can bring catalog of shared human knowledge. scientific historical evidence and the very For a full discussion of the issues essence of scientific inquiry into conflict associated with the teaching of natural with deeply held beliefs concerning the selection, biological evolution, and the sacred origins of life. Both points of view origin of species, obtain this book or seek to answer the same questions, in a browse it on-line: Teaching about Evolution and where did I way: How did I get and the Nalure of Science. Details are in the come from? References chapter. Evolutionary biologists study the scientific evidence provided by the inventory of living organisms, and piece together the fragments of life's prehstory, to synthesize a credible story for the emergence and progressive redesign of life on Earth. According to the biologst, the 3.5-billion- year ongoing experiment has produced Homo sapiens and the several millions of other species living on Earth today. And the biologist suggests that, just as it has from the beginning, the description, distribution, and diversity of life on Earth today is a snapshot of a work in progress. The evolutionary processes will continue to reshape the image of life on Earth indefinitely. We are here now simply as a result of chance and natural selection, just like every other living thng. Ths course introduces students to the scientific explanation for the origin of species and, in the process, lays the groundwork for answering the questions of how I got here and where I came from. It is not the intent of this course to disparage the belief system of students. Rather, we present the science ideas and