PRISM UHH GK-12 Natural Selection Hawaiian Origami Birds · selection is the process by which favorable traits that are passed on over ... n er a tions syou c hm l od.U b o or ul

Natural Selection Concepts In 1859, Charles Darwin and Aflred Russel Wallace proposed the theory of evolution by natural selection. Their theory was later combined with Mendelian inheritance to explain the connection of genes (units of evolution) and natural selection. This theory has become the principle explanation for species diversity. Standards addressed 7.5.4, 7.5.6 Duration 1 60 minute class periods Source Material w w w.indiana.edu/~ensiweb/lessons/origami.html Vocabulary Natural Selection Phenotype Genotype

Hawaiian Origami Birds

Summary After students have a strong understanding of Adaptations and Genetic Variation, they will be introduced to Natural Selection. They will participate in a natural selection simulation in which they will create and modify “paper airplanes” over several generations to visualize how favorable heritable traits are passed on. These paper airplanes represent wild birds of a population. Objectives

• Students will simulate how genes are passed from one generation to the next.

• Students will understand how traits that are favorable for survival become more common over generations.

• Students will know that both genetic variation and environmental factors causes of evolution and species diversity.

Materials Paper Ruler Tape Straws Scissors Coin Six-sided die Background The Hawaiian Origami Bird (Aves hawaiiensis) lives on the rugged coastline of Hawaii Island. It feeds on Opae'ula (Halocaridina rubra) which are found in anchialine ponds around the island. Due to high development of the coastline on the island, alchialine pools are decreasing and becoming less common. Only 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.

PRISM UHH GK-12 PRISM UHH GK-12

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 procedure section can be Xeroxed and handed out or the diagrams can be written on the board.

Procedure 1). Split students 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 offspring. Each Origami Bird lays a clutch of three eggs. Record the dimensions of each chick and hatch the birds using these instructions:

a. The first 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 chick, flip your coin and throw your die then record the results on the table.

i.) The coin 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:

kujkjkjkjkjkjkjkj

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 is smaller than the circumference of the straw, etc. is lethal. Fortunately, Aves hawaiiensis birds are known to “double clutch” when an egg is lost. If you should get a lethal mutation, disregard it and breed another chick. 3). Test the birds: Release the birds 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 chick 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 as 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 and assessment You can use the 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 experiment result in better flying birds? 2. Evolution is 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 your youngest bird with your neighbor’s youngest bird. a. Compare and 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 .produce 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: _kk 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.

No Mutation COIN COIN 3 x 20 3 x 20 _________x _________ x Head k Tail Head Tail Head Tail DIE DIE 3 cm 3 cm

Natural Selection Concepts Changes to the environment may affect how an organism may survive in the wild. Occasionally, organisms have the ability to activate different phenotypes in response to its changing surroundings. This lesson uses an endemic Hawaiian tree species, Ohia, to show how this species changes its phenotype in response to different habitat requirements. Standards addressed 7.5.4, 7.5.6 Duration 1 full day for field trip Vocabulary Natural selection Phenotype Genotype Glabrous Pubescent Phenotypic plasticity Source Material PRISM

Exploring the Ohia Common Garden

Summary After students have a strong understanding of Adaptations and Genetic Variation, they will be introduced to Natural Selection. They will visit the Ohia Common Garden in Volcano, Hawaii to see how Ohia (Metrosideros polymorpha) from different elevations have morphological differences. Objectives

• Students will simulate how genes are passed from one generation to the next.

• Students will understand how traits that are favorable for survival become more common over generations.

• Students will know that both genetic variation and environmental factors causes of evolution and species diversity.

Materials Background information about Ohia to lecture students before visiting garden Permission to visit the garden Dr. Elizabeth Stacy-can give presentation at garden about Ohia Background 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. 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.

PRISM UHH GK-12

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, University 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 finalizing the plans to visit the Ohia common garden, give the students some background information on Ohia before visiting 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 tree 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 completed, have the students write a reflection about their trip to the garden. They could also be asked to research another organism that displays phenotypic plasticity. Assessment Journal writing Written report 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 the same genotype) grown in sunlight would look different from tomato plants grown without sunlight. Have 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. The 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 affect 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 m a y 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 u p all new understanding of the progression of that is good; silently and insensibly working, life emerged.

whenever and wherever opportunity offers, at the improver~en t ofeach organic being i n relation to its organic and inorganic conditions

NATURAL SELECTION

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 as resident naturalist aboard the survey ship Beagle. The impact of the incredibly diverse and complex biota he encountered in South America revolutionized his perception of life on Earth. During the voyage and the years following, Darwin formulated a theory explaining the uniqueness and origin of the organisms he discovered. It was many years, however, before he finally published his famous book, O n the Origin of Species by Means of Natural Selection, in 1859.

Darwin anguished over his manuscript. He was diligent in his science, wanting solid sources of evidence for his sveculative ideas. But even when the

Nature Produces Variation. During the process of reproduction, random changes occur in the genetic information directing the manufacture of a new unit-an offspring. Extreme changes are usually lethal, and no offspring result. Those genetic miscues are not perpetuated. Modest changes translate into often subtle and sometimes dramatic differences in individuals. Individual offspring turn out to be unique; one perhaps a little larger, another more aggressive, and still others darker in color, slower to respond, having larger fins or wider teeth, on and on. The result is variation in populations.

Life Is a Challenge. Many factors I converge to prevent organisms from

theory was clearly described and enjoying a peaceful, relaxed, successful

supported to h s satisfaction, 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. Heterotrophc organisms eat other

organisms for energy and building blocks. Organisms that fail to acquire food die.

On the other side of that equation, organisms that are taken for food also die. Microbes sometimes invade organisms, causing disease. Life is always under pressure.

Organisms in a Population Compete. Every species has a niche in which it lives and acquires the resources it needs for survival. The problem is, all the other members of an organism's species are trying to make a living in that niche as

well. This creates competition among members of a population for access to limited resources. If resources are not limited, members of the population could coexist without complications. Those individuals that succeed in getting resources and that successfully reproduce pass their genes to the next generation.

The measure of the success of an individual organism is whether or not it survives and reproduces. The traits that prepared a successful organism to

The measure of the success of a population

is its ability to withstand change in the environment and to prevail. Nature's

hedge against complete disaster imposed by disease, drought, or hoards of predators is variation. When a new pressure is imposed on a population, some individuals may succumb. But some will likely have adaptations that allow them to survive and reproduce more offspring than other individuals of that species. In this way the population continues, but

changes.

Darwin did not have the benefit of understanding the fundamentals of genetics, although it was well accepted that organisms passed the code for making reasonably accurate reproductions of themselves from generation to generation through sexual processes. He was able to observe firsthand the variation within a population, particularly when he observed the finches on the Galfipagos Islands. The puzzle that Darwin pursued was how the countless kinds of organisms came into being. What forces created a new kind of organism? What was the origin of species?

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, influencing the distribution of traits in the

individuals. The population changes in response to selective pressure. (Notice, individuals don't change in response to selective pressure; they only survive or die. Populations change depending on the characteristics of the survivors.)

Over time a population may change sufficiently for science to judge it to be a different kind of organism than it was before the selective pressure was brought

to bear on the original population. How long does that take? And how different does the "new" population have to be to be deemed a new species?

It isn't easy to answer these questions. A new species may emerge in an extremely short time-a matter of days or weeks in

the case of bacteria. Or it may take millions and millions of years for a successful species like the white shark or horseshoe crab to change enough to be considered a new species.

Darwin observed the finches on the GalApagos Islands. The 20 or so islands are situated about 1000 km west of Ecuador. The current islands range in age from about 700,000 to 4 million years, but scientists suggest that there may have been other islands or sea mounts in the area as long as 10 million years ago. The point is that the GalApagos Islands are young, and any terrestrial life had to make its way there across the open sea or through the air.

Some time ago a single finch species arrived on the islands. Perhaps a small flock was blown off course in a storm. The birds apparently had no competitors for

resources, and they thrived. As time passed, variation entered the population. The most conspicuous variation was the beak. Different subgroups within the

population were better adapted to exploit different food sources. We can imagine that the members of the population that

sought similar food sources would associate, and other groups that shared different traits would associate. Feeding behavior isolated subgroups within the larger population. Breeding among the subgroup reinforced the trait that isolated it in the first place, further separating the subgroup.

Variation within the subgroup might have produced other traits that also tended to isolate the subgroup, perhaps coloration, size, nesting habits, mating rituals, and so forth. In time, isolation and change in response to pressures from the environment produced a new subspecies. The exact time at which a splinter group is awarded the status of species is a subject

for scientific debate. There are few absolutes for defining a species, so the moment at which it happens is nebulous.

Darwin concluded that speciation was a

natural outcome of ongoing life processes: (genetic) variation in a population, selective pressure in the environment, and

isolation of a segment of the population. Darwin's momentous discovery is often summarized as "survival of the fittest." This creates a mental image of a ferocious battle for survival, with the biggest, strongest, most voracious individuals always surviving to continue their kind. This is not an accurate picture. Fittest doesn't necessarily mean the individual in the best condition or the one with the

biggest teeth and strongest bones. It means the individual with the best adaptations to survive the pressure being

imposed by the environment. Fittest simply means the best equipped to survive and reproduce.

Who or what determines fitness? The selective pressure in the environment. The pressure might come from the weather. A return of the ice ages will select for those individuals with adaptations for surviving cold and select against those without adaptations for cold. A new predator that climbs trees will select for those tree- dwelling individuals that can flee or defend against the predator, and select against those that have no defensive adaptations. A drought that reduces the acorn crop may select for the smaller members of a population that can survive on less food and select against those that require more food. The result of natural selection is that the genetic makeup, and therefore the suite of traits expressed by the population, is constantly changing. The change process in organisms is called evolution. Organisms can be thought of as work in progress; they are constantly evolving from something into something else.

If you follow the evolutionary process back in time, perhaps 3.5 billion years or so, logically you eventually arrive at the first living organisms on Earth. Remember, life is the Olympic flame that burns in every organism. The flame is handed from one organism to the next. If

through millions and millions of handoffs without a fumble.

The processes of variation, natural selection, and isolation have produced an amazing array of organisms. There are millions of species alive on Earth today, and for each one there were at least a hundred species that are now extinct. The process of evolution has produced a continuous parade of new species, each adapted to the specific environments in which it lived, and continues to do so today.

ARTIFICIAL SELECTION

A discussion of artificial selection might shed light on the selection process. We humans have one adaptation (thanks to natural selection) that makes us a formidable organism to deal with-an advanced brain. We can control our environment to an unprecedented degree. As a result we can manage food resources, create shelter, manipulate energy, control other organisms, and re-create the world we live in.

One human enterprise is manipulating the traits of organisms through artificial selection. Think about the domestic dog. Every breed From the skinny, shivering Chihuahua to the robust, barrel-toting St. Bernard, and all the retrievers, hounds, terriers, poodles, spaniels, bulldogs, collies, and Pomeranians in-between are the same species. Where did all the diversity come 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 enthusiastic about water and swims well. A retriever or a spaniel would be a good breed to start with. So you get a bunch of

retrievers and spaniels and show them a squid. Toss the squid in the water and see whch dogs jump in to grab it. Of the original subset of water-loving dogs, only a few will pass the "goes for squid" test. Breed the squidophiles and raise the pups. Test them for squidophilia. Breed the most promising of those.

Take the best squidders out in a boat and see how good they are at spotting a squid in the water. Breed those with the best night vision. What's the best color (maybe black) and hair length (shorter the better). Identify those sharp-eyed squidophiles that have the darkest, shortest fur. The

animals that have the traits that fit your needs are the ones that you allow to reproduce to get more offspring with their traits.

After many generations of selective breeding you produce a squid hound, equal to the task you want it to perform. And if you find you are not completely satisfied with the dog's performance in the future (maybe the breed shakes after getting back into the boat after snaring a

dysfunction, or shvering, shows up as a trait in the breed, it may be difficult or impossible to breed it out without losing the traits you selected for in the first place.

A reduced gene pool caused by inbreeding often introduces vulnerability and weakness into the breed, due to lack of variation.

Artificial selection has been used for years to develop disease-resistant strains of grains, higher-yielding corn, faster- maturing soybeans, square tomatoes, seedless watermelons, and hundreds of other agricultural plants. And, of course, horses and livestock are selectively bred for a variety of functions and products, and the celebrated silk moth and the large and exotic goldfish called koi have been selectively bred for centuries to produce the living products we see today.

Nahire does the same, but without purpose, allowing some individuals with the right stuff to produce more offspring than others in the population. But in nature, the selection is based on passing a test, not possessing arbitrarily desirable traits. And the "right stuff" is having the traits that better prepare the offspring to survive and reproduce, not measuring up 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 way: How did I get and where did I 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.

T h s 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