Download Natural Selection of the Galapagos Origami Bird

Natural Selection of the Galapagos Origami Bird (Avis papyrus)
and the DNA Connection
A Simulation of the Natural Selection of DNA Mutations
Based on original Origami Bird lessons by Karin Westerling,
and a DNA Version by Takahiro Yamanoi et al
SYNOPSIS
Students participate in a contrived natural selection simulation in which they build and modify simple paper
airplanes out of straws and paper ("Origami Birds") and generate four generations selecting for flight distance.
To do this, students must make changes in the structures of the new "birds" of each generation. Those changes
represent the results of random "mutations" in the DNA of each new bird, changes determined from the results
of two random actions: spinning two random spinners. Each new bird is "flight-tested". The best-performing
offspring (as defined by the teacher) then serves as the parent to the next generation, where the process is
repeated. SPECIAL NOTE: See YouTube video of students doing this study (Resources at end of paper).
PRINCIPAL CONCEPTS
Students will demonstrate that:
1. Mutations occur randomly. They are NOT purposely designed or intended to meet current survival needs.
2. Inherited characteristics (whether mutated or not) are contingent on the genetic features available and the
current environmental conditions.
3. Selection is based on ( contingent with) what the current environment allows to survive and reproduce.
Selection is NOT based on the immediate "needs" of the organism.
Concepts Clarified by the DNA Extension:
4. Phenotype is linked to the genes. A change in a gene (due to mutation) can cause a change in a trait.
5. Natural selection is not Lamarckian: changes do NOT occur "in order to" or "so that" an organism can
survive. Changes do NOT occur because the organism "needs them in order to survive."
ASSOCIATED CONCEPTS
6. Divergent evolution may occur when two sub-populations face two different environments.
7. Convergent evolution may result in different populations independently solving a similar problem by
producing similar features.
8. One cause of speciation is isolation of sub-populations.
9. Mutation is not "speciation." Typically, a single mutation does not produce a new species. It takes an
accumulation of mutations over a number of generations over time, producing gradual changes in
phenotypes, until a sufficiently changed (and reproductively isolated) group (population) can be called a
new species.
ASSESSABLE OBJECTIVES (Students will...)
1. recognize that natural selection is NOT a totally random process.
2. recognize that while mutations and genetic recombination are random processes, selection is not random; it
is directly contingent on genetic makeup in context with current environmental conditions.
3. recognize that gene changes can result in changed traits.
4. recognize that organisms do NOT change in order to survive or to meet a particular need.
5. recognize that natural selection, as the basic mechanism of evolution, has no preconceived direction, and is
not based on need.
6. recognize that significant changes in structures and behavior by natural selection typically occur in small
steps (minor changes) accumulated over many generations, not just in one generation.
MATERIALS
For Teacher: PDF copy of this lesson; Key for discussion (contact webmaster using your school email).
For Each Team:
4 straws (non-bending)
Gametes Mutation Box (GMB)
Mutation Table
paper for cutting wing strips
Plastic sheet covering GMB
Results Sheet 1
scissors
Dry-erase pen
Results Sheet 2
clear tape
Random Spinner #1 (see below)
Masking tape
paper clips
Random Spinner #2 (see below)
Tape measure (metric)
Have extra straws and paper available for students to make additional birds in subsequent generations.
Straws should be large ones, about 7 mm x 21 cm long, if possible.
Have enough tape measures or meter sticks available for teams to measure distances. Check out to students.
Have a bag or tray for each team (in each period) to store its "birds" and scraps in overnight
Optional: Have a simulated layout of "islands" (irregularly shaped brown paper), with blue "freshwater
springs" and model palm trees on each island, all to simulate the environment of the study.
Instructions for making the two random spinners and the Gametes Mutation Box are provided below.
STUDENT HANDOUTS:
For Students: Information packet: Background, Introduction, Materials, Getting Ready, Building Birds,
Flying the Birds, Discussion Questions
Results Sheets (2 graphically formatted data recording sheets: P, F1, F2 on one, and F3, F4) on the other).
TIME: About 2-3 days for first efforts. Should take only about 90 minutes with experience.
TEACHING STRATEGIES & PREPARATION
Differences between this DNA connection version and Karin Westerling's original Origami Bird:
1. In the original, mutation always caused a phenotype change, whereas in the DNA version it does not.
2. In the original, mutation occurs in only two thirds of the offspring; in the DNA version, mutation occurs in
all the offspring. This is because in an actual organism, it is believed that gamete formation (production
of eggs and sperm) necessarily accompanies mutational changes in DNA (Yamanoi, et al 2012, p. 296).
3. In the original, randomness was accomplished with coin flips and dice throws. In the DNA version,
randomness is obtained from two random "roulette-type" spinners, a "Gametes Mutation Box" (see
Figures 3-7), and a printed Mutation Table (developed by Dr. Yamanoi).
4. Starting wing size in original: 3 cm x 30 cm. Starting wing size in DNA version uses 2 cm x 20 cm to start.
5. Original context was desert with oasis destinations; DNA version context is ocean with island destinations.
Background: There are no teaching materials that effectively connect DNA sequence changes to the process of
natural selection. Furthermore, misconceptions about evolution among high school students are reported in
many studies in several countries. Even after studying evolution, many students fail to understand modern
evolutionary concepts, e.g., linking genes to phenotype, and they mistakenly think that the mechanism of
evolution is a process that is essentially Lamarckian and orthogenetic (evolution toward fixed goals). These
misconceptions may be derived from inadequate understanding of the role of randomness in natural selection.
If students can see mutation as a truly random, not a purposely designed process, then they should recognize
that natural selection is not a Lamarkian or orthogenetic process (Yamanoi, et al 2012).
The original Origami Bird lesson available on the ENSI website, was created and developed by ENSI teacher
Karin Westerling in 1992. In the accompanying narrative, the origami bird (Avis papyrus) supposedly lives in
arid regions of North Africa. Only those birds that can fly the long distances between oases live long enough to
breed successfully. Each bird lays a clutch of three eggs. The first egg has no mutations (it's a clone of the
parent), and the other two eggs have mutations that affect the chicks' morphology (structures). The
morphological changes often cause changes in the capabilities to fly long distances.
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When Westerling's version of Origami Bird natural selection was carried out in a Japanese high school, it was
found that the students still did not fully understand that the random processes of coin flips and die throw
represented random mutation, and furthermore that mutation can involve random DNA alterations, possibly
resulting in modification of bird structures. Therefore, they mistakenly thought that the birds evolved
teleologically (i.e., for the purpose of reaching an oasis). So the teacher of that class developed a procedure to
repair those misconceptions. The following lesson is based on the paper published by that teacher (also a
professor of science education), Dr. Yamanoi (Yamanoi, et al 2012).
Construction of the Random Spinners: Various kinds of spinners have been used, but every effort must be
made to assure that they spin freely and stop in a truly random way. Such a spinner can be found at the
Resource Area For Teachers (RAFT). Locations for this organization are currently in San Jose, Sunnyvale, and
Sacramento, CA, and in Denver, CO. Addresses can be found HERE. http://www.raft.net/visit-raft-locations
The RAFT Online Store is HERE http://www.raftstore.net/ The instructions for making the "Spinner on a
Media Tray", are HERE. http://www.raftbayarea.org/readpdf?isid=562 Most materials can be found at a local
arts & crafts store, or a RAFT if one is near you. The easiest way is to contact the San Jose RAFT at (408) 4511420 to order enough spinner-making kits for your class at 50¢ per kit + packaging and postage (remember: 2
spinners per team). For example, in a class of 32 students, you will have 8 teams of 4 each, so you will need 16
random spinners. Good idea to order a couple more for backups, too. An improved variation of these kits uses
both halves of an ultra-thin (5 mm thick) clear CD holder, with the spinner face inside, and the spinning arrow
outside the case above the spinner face. This requires drilling a small hole in the lid center to accommodate the
brass fastener. Colored spinner selection faces for the two spinners can be seen and downloaded from the ENSI
site HERE. Ultra-thin clear CD holders might be available at low cost from the RAFT (San Jose, at least). Just
ask. Click HERE to see photos of the Gametes Mutation Box (Fig. 3) and the Random Spinner Assemblies
(Figures 4-7).
Preparations: In addition to having all the materials ready to use for each team, be sure to arrange for a flighttesting area nearby. This could be the hallway or corridor or other nearby space outside the room. An alternative
could be any empty classroom nearby (with permission of teacher(s) who normally uses the room. You might
need a different classroom for each of your classes. On the ground (or floor), place strips of masking tape (or
other marker) to serve as the "take-off" point, from which students will launch their birds. If feasible, try to have
a few simulated "islands" located about 10 meters apart (for visual influence). If you don't have several tape
measures (10 feet or more), check with coaches or shop teachers. If possible, obtain a few metric tape measures.
Be sure that each flight-testing area has clear lanes for unobstructed flights.
Show the class how to do the setup and first generation procedures (using white board, overhead or projector,
and sample origami birds). Walk around while they do that, followed by the second generation, etc. Decide (and
announce) whether you want them to test-fly each bird once, or get averages from 2 or 3 flights. Can take about
30 minutes for each generation.
YouTube of Origami Birds Study: Dr. Yamanoi has prepared a YouTube video (in Japanese) showing how
birds are made and flown, and how data are recorded and analyzed. Lots of good ideas for modifying the lesson.
Also a new article (by Dr. Yamanoi) about the development of an Origami Bird computer simulation. The
simulation program is available for download at https://github.com/heavywatal/oribir/ . However, I have had
problem getting it to run. If you can run the program, please let us know.
Side Notes: Dr. Yamanoi (2012, fig. 1) points out that "origami" is actually Japanese for "not balling up" and
therefore implies "folded paper." But the "birds" used in this study are actually not folded, so this can be
confusing to Japanese students. [Ed.: It was tempting to consider renaming the lesson, perhaps something like
"straw bird" or "mosaic bird." But Origami Bird has become so tightly associated with the original lesson that it
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will be retained]. Consider attaching the GMB and Mutation Table inside manila folder for each team, with
smooth plastic covers taped over them on which the DNA mutations can be marked with dry-erase pen.
Also, further confusion can come from how the Japanese understand "mutation." They generally regard
mutation as a large shift, e.g., speciation, because the word for mutation literally means "sudden change"
(Yamanoi et al, p. 293). Therefore, it's very important that your audience fully understands what makes a
genetic mutation: generally, it's a changed gene (in addition to various chromosomal changes). There are several
ways that genes can change, but in this lesson, for the sake of simplicity, only the changes by DNA base
substitutions are being used. Also, significant changes typically occur from several mutations accumulated
over several generations (see the ENSI lesson: Natural Selection: a Cumulative Process which clearly
demonstrates the power of accumulated changes).
PROCEDURES
Overview: Students should work in teams of about 4. Instead of using coin flips and dice throws (as in the
original Origami Bird lesson), we will use the "Gametes Mutation Box" (GMB). The GMB is accompanied by
two random spinners: one determines which one of the 5 DNA bases mutate, and the other one determines
which one of the 4 possible bases replaces the previous base there. After the DNA replacement (mutation) is
made, the phenotypic (structural) change caused by that mutation is found (on the "Mutation Table"). Then the
appropriate changes are made for the new bird. This process is repeated for each of the 3 new birds in the
coming generation.
At this point, the three new birds are taken to the "Flight Testing Area." This could be a nearby empty hallway
or empty room, where a strip of masking tape marks the "take-off" (start) line. As each bird is thrown three (or
two) times, its landing point is marked with a bit of tape and distance measured with tape measure from the
take-off line. Average distance is calculated from those three flights. (If time is tight, tell students that each bird
is launched only once). It's best to have a "tape holder," a "measurer" and a "recorder" to expedite this process
quickly. After all three birds are flown three times each, their distances recorded and averaged, return to your
classroom.
Using the "winner" bird as the "new parent," generate the mutations and create the next generation of three
birds. They will all be genetically the same as this new parent EXCEPT for their new mutations. The "winner
bird" would be the one that had the longest average flying distance. An alternative winner could be the one that
flew the average shortest distance, which might be the case in a forested environment. See the student handout
for specific steps in this process.
ASSESSMENT: See Assessable Objectives for focus of assessment.
Meeting NGSS Performance Expectations: <http://www.nextgenscience.org/search-standards>:
The NGSS performance expectations for middle school and high school do specify the importance to
understand the role of genetic variations and mutations in natural selection. Many people (even some
teachers) may not understand these elements accurately, and therefore may pass those misunderstandings on to
their students. This modification to Karin Westerling’s “Natural Selection of Origami Birds” is, therefore, a
most welcome (and highly recommended) way to give students that accurate understanding. Here are those
three NGSS expectations (boldface emphases added):
MS-LS4-4:
Construct an explanation based on evidence that describes how genetic variations of traits in a population increase some individuals’ probability of
surviving and reproducing in a specific environment. [Clarification Statement: Emphasis is on using simple probability statements [of random
events] and proportional reasoning to construct explanations.]
HS-LS4-1:
Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence.
[Clarification Statement: Emphasis is on a conceptual understanding of the role each line of evidence has relating to common ancestry and
biological evolution. Examples of evidence could include similarities in DNA sequences, anatomical structures, and order of appearance of
structures in embryological development.]
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HS-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. [Clarification
Statement: Emphasis is on using evidence to explain the influence each of the four factors has on number of organisms, behaviors, morphology, or
physiology in terms of ability to compete for limited resources and subsequent survival of individuals and adaptation of species. Examples of
evidence could include mathematical models such as simple distribution graphs and proportional reasoning.] [Assessment Boundary: Assessment
does not include other mechanisms of evolution, such as genetic drift, gene flow through migration, and co-evolution.]
EXTENSIONS & VARIATIONS
1. For motivation, and to simulate the environment favoring selection for distance, place a simulated "islands"
about ten meters apart and from the launch line: a few irregular or circular pieces of brown construction
paper, perhaps with model palm trees and light blue paper/material for freshwater springs on them.
2. Consider having half of each class (or alternate classes) run the study with environmental factors favoring
short flight distances, and students should share their results so they can see how random mutations,
acted upon by different selective forces, produces distinctly different results. A simulated dense forest
might serve as the short-distance environment, or small islands close together with "shark-filled waters"
surrounding the islands.
3. Share references to the use of natural selection for STEM applications, finding designs that most effectively
solve specific problems. http://www.indiana.edu/~ensiweb/STEM.Apps.Nat.Sel.html
4. SPECIAL PROJECT? Students (small groups) can consider doing a special investigation, using different
conditions as described below (or other conditions they would like to try), courtesy of K. Westerling:
A. A flock of Origami Birds is blown off the mainland and onto a very small Mediterranean island.
There are no predators here. Like the flightless fruit flies (Drosophila spp.) of Hawaii and the
Dodo (Raphus cucullatus and Didus ineptus) before the arrival of humans on Mauritius and
Réunion, these birds face little danger on the ground, but experience significant risk when flying,
since they can be blown off the island. The best survival strategy for these birds is not to fly at
all. Continue the study for several generations selecting for birds that drop out of the sky the way
flying bricks do.
B. Another flock of Origami Birds is blown onto a different, somewhat larger, island. Silver Scissor
Foxes (Vulpes cisoria ssp. argentatum) live on this island, so birds that cannot fly will be eaten.
The best survival strategy for these birds is to fly in boomerang or loop-the-loop curves. Birds
that fly straight might drift off the island and be swept away. Continue the study for several
generations selecting for curved flight.
C. Your Origami Bird found its way on the mainland where a drought is occurring. Only those birds that
can fly straight and far between oases will survive. Continue the study for several more
generations while selecting for the characteristics that result in the most appropriate flight
behavior.
RESOURCES
Yamanoi, Takahiro. Author's class Making, Flying and Studying Origami Birds (in Japanese). YouTube:
https://www.youtube.com/watch?v=In1EWrOmWAs
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REFERENCES
Yamanoi, Takahiro and Watal M. Iwasaki. 2015. Origami Bird Simulator: A Teaching Resource Linking
Natural Selection and Speciation. Evolution Education and Outreach, August 2015.
Electronic Version: http://www.evolution-outreach.com/content/8/1/14
PDF Version: http://www.evolution-outreach.com/content/pdf/s12052-015-0043-6.pdf
Yamanoi, Takahiro, et al. 2012. Improved "Origami Bird" Protocol Enhances Japanese Students' Understanding
of Evolution by Natural Selection: a Novel Approach Linking DNA Alteration to Phenotype Change.
Evolution Education and Outreach, 5(2): 292-300. June 2012.
http://link.springer.com/article/10.1007/s12052-012-0388-z/fulltext.html
Yamanoi, Takahiro. 2014. Personal communications.
ATTRIBUTIONS
Karin Westerling and the original Origami Birds lesson that she created.
Dr. Takahiro Yamanoi of Hakuoh University, and team, for their Origami Bird variation using randomly
generated mutations as the source of structural variations.
Secondary science teachers who have field-tested the DNA Connection and shared their experiences:
Thomas Wanamaker, Kathy Hallett, Nathan Hoekstra, Elaine Westbrook, and Karen Truesdell
Adapted for ENSI site by Larry Flammer. November 2015.
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