pitx1 gene stickleback pitx1 gene stickleback

Text/Curriculum Curriculum Topics Sample Models: This site needs JavaScript to work properly. Proc Natl Acad Sci U S A. natural selection, mutation, adaptation, genes, proteins, protein-coding region, mutations. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. 8. Pelvic loss in different natural populations of threespine stickleback fish has occurred through regulatory mutations deleting a tissue-specific enhancer of the Pituitary homeobox transcription factor 1 (Pitx1) gene. Students interpret molecular diagrams and build physical models of eukaryotic gene regulation. P50 HG002568/HG/NHGRI NIH HHS/United States, P50 HG002568-09/HG/NHGRI NIH HHS/United States, HHMI/Howard Hughes Medical Institute/United States, P50 HG02568/HG/NHGRI NIH HHS/United States, NCI CPTC Antibody Characterization Program. 11. Figure 2 illustrates how Pitx1 transcription is regulated in different tissues. Describe the function of regulatory switches. Any items that can represent proteins. 625 0 obj <> endobj Gene regulation is essential for the cell to perform the functions needed to live. In this activity, we will talk about how gene expression is regulated through transcription. You isolate DNA from jaw, pelvic, eye, and pituitary The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. xxtyZe4RR6OrF%'U/b_[?"j9;`{k{`;eG;cgK6bcMX)l-X;~k7,l|9;ia3i7X&%iXR Make sure that students have placed an X over the pituitary switch in all four tissues. Unauthorized use of these marks is strictly prohibited. PITX1 (Paired Like Homeodomain 1) is a Protein Coding gene. According to the film, what is the selective pressure that led to freshwater stickleback fish losing their pelvic spines? 1. 8600 Rockville Pike 2011 Oct The large grey rectangle represents the protein-coding region of the Pitx1 The smaller rectangles to the left (b and c) are regulatory switches (networks of regulatory genes); each one . If a fish does not produce activator 3 proteins, Pitx1 will be expressed in which of the following tissues? In this activity, we will talk about how gene expression is regulated through transcription. Based on the information from the film, what is the difference in the DNA around the Pitx1 gene region between The appropriate activator proteins are in the appropriate tissue. Common Core* CCSS.ELA-Literacy.WHST9-12, CCSS.ELA-Literacy.RST.9-12, Chen HI, Turakhia Y, Bejerano G, Kingsley DM. Investigation: Regulatory Switches of the PITX1 Gene in Stickleback Development. Use the information from the film and your knowledge of eukaryotic gene transcription to answer questions 5-9. in two morphologically different populations of stickleback fish. Hum Mol Genet. Pitx1.) Transcription factors specifically bind to the promoter to activate transcription. Viral Lysis and Budding. o Pituitary switch binding activator (yellow). stickleback fish does not. Different Genes Cause Loss of Body Parts in Similar Fish Interestingly, protein production can be regulated at the translational and transcriptional steps, as well as after a protein is produced. learn about the proteins involved in eukaryotic gene transcription. It is the gene that regulates the formation of hind limbs in mice and other four-legged animals; scientists don't yet know whether stickleback fish have a Pitx1 gene. Besoke R, Held K, Mundlos S, Kurth I. Deletions in PITX1 cause a spectrum of Some genes, especially genes involved in body development, have multiple switches. U.S. Department of Health and Human Services, hindlimb expressed homeobox protein backfoot, hindlimb-expressed homeobox protein backfoot, paired-like homeodomain transcription factor 1. : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Investigation:_Modeling_Independent_Assortment_and_Dihybrid_Crosses" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Investigation:__Regulatory_Switches_of_the_PITX1_Gene_in_Stickleback_Fish" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Karyotype_of_Tasmanian_Devil_Chromosomes : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Meiosis_Worksheet : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Practice_Problems:_Genetics_and_Blood_Types" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Teddy_Graham_Lab : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Variations_on_a_Human_Face : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "What_is_a_Map_Unit_Anyway?" The PubMed wordmark and PubMed logo are registered trademarks of the U.S. Department of Health and Human Services (HHS). Answered: Regents Practice: Base your answer to | bartleby In some cases, these mutations confer a selective advantage for that cell and that mutation will be (3) B cells, which are part of the immune system, have DNA that has been rearranged to make antibodies. The presence of multiple switches enables the same gene to be used many times in different contexts This animation is a clip from a 2005 Holiday Lecture Series, Evolution: Constant Change and Common Threads. Mediators. switch mutation? J, Lohan S, Dathe K, Nardone AM, Ferrari P, Landi A, Wittler L, Timmermann B, development. This investigation was modified from the HHMI Stickleback Modeling activity where students examine two different forms of the the stickleback fish. 4. Label the boxes in Figure 1 with the letters a-e, which correspond to the terms listed below. The Pitx1 gene has multiple regulatory switches that control the expression of the gene in different tissues: the pituitary, jaw, and pelvic tissues. In reality, many activators are present in a particular tissue at any one time. Correctly interpret visual representations of eukaryotic gene transcription. 691 0 obj <>stream 2. The three exons of the stickleback Pitx1 gene encode a 283-amino-acid protein that shows extensive sequence identity to Pitx1 sequences previously reported from other fish, birds and mammals . This piece will not be used in the activity, but you the exceptions listed in the Key Concepts and Learning Objectives. HHMI BioInteractive. The .gov means its official. J Hered. Kingsley's previous studiesshowedthat the loss of the stickleback hindfin maps to a gene called Pitx1, which mediates the development of hindlimbs in many vertebrates, and is also required for pituitary and jaw development. 6. Explain the role that regulatory switches play in determining whether stickleback embryos will develop pelvic spines. How can a spined stickleback fish have the exact same PitX1 sequence as a spineless stickleback? Regulating that expression simply means turning on or off or increasing or decreasing the production of a given protein. For example, in the cells that develop into the pelvis there is a specific activator (activator 2) that binds to the pelvic switch to transcribe Pitx1 in that tissue. Students review eukaryotic gene transcription using the example of a gene called Pitx1, which is . Stickleback fish are small and have short generation times. Models serve many purposes. Figure 1 is a diagram, similar to the one shown in the film (8:00-8:34), showing key components of gene transcription. : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "How_Do_Bunny_Populations_Change_Over_Time?" The Google Drive folder is set as View Only; to save a copy of a document in this folder to your Google Drive, open that document, then select File Make a copy. These documents can be copied, modified, and distributed online following the Terms of Use listed in the Details section below, including crediting BioInteractive. 2013 Feb 1;374(1):234-44. doi: 10.1016/j.ydbio.2012.11.017. PDF | Adaptive ecotype formation can be the first step to speciation, but the genetic underpinnings of this process are poorly understood. Having multiple switches enables Pitx1 to be used many times in different contexts and expands the versatility of that gene. : an American History (Eric Foner), Forecasting, Time Series, and Regression (Richard T. O'Connell; Anne B. Koehler), Brunner and Suddarth's Textbook of Medical-Surgical Nursing (Janice L. Hinkle; Kerry H. Cheever), Campbell Biology (Jane B. Reece; Lisa A. Urry; Michael L. Cain; Steven A. Wasserman; Peter V. Minorsky), Psychology (David G. Myers; C. Nathan DeWall), Chemistry: The Central Science (Theodore E. Brown; H. Eugene H LeMay; Bruce E. Bursten; Catherine Murphy; Patrick Woodward), specific manner. Describe the difference between an operator and an enhancer. You isolate the DNA from the heart of the freshwater stickleback that lack pelvic spines. Investigation: DNA, Proteins, and Sickle Cell, PART 2: REVIEWING THE REGULATION OF EUKARYOTIC GENE TRANSCRIPTION, PART 3: GENE REGULATION IN DIFFERENT TISSUES, status page at https://status.libretexts.org. 10. In multicellular eukaryotes, gene regulation is also important in building bodies. Y transcription. It is the gene identified to be involved in the formation of the pelvic spines in stickleback fish, as well as hind limb development in other vertebrates, such as the mouse. List three limitations Many freshwater populations of stickleback fish lack the long spines that project from the pelvis of their marine relatives. Legal. As you saw in the film, the presence or absence of pelvic spines in the stickleback fish is controlled by whether the Pitx1 gene is expressed in the pelvic tissue. check mark next to the tissue(s) that will express Pitx1.) The large grey rectangle represents the protein-coding region of the Pitxi gene. e. RNA polymerase. Infante CR, Park S, Mihala AG, Kingsley DM, Menke DB. Development of the lower limbs is normal in people with this condition. Use the information from the film and your knowledge of eukaryotic gene transcription to answer questions 5-9. April 4th, 2012 - Genomics Stickleback is the catch first whole genome sequence of the threespine stickleback do not provide simple yes or no answers to such Studies of threespine stickleback developmental evolution April 26th, 2018 - Studies of threespine stickleback developmental evolution of threespine stickleback developmental evolution PITX1 gene: MedlinePlus Genetics identified in question #5 to show active eukaryotic gene transcription. Explain the role that regulatory switches play in determining whether stickleback embryos will develop pelvic spines. genetics - How is the "fine mapping of pelvic regulatory region" done Contact a health care provider if you have questions about your health. Interactive Assessment for Evolving Switches, Evolving Bodies Evolution generates a remarkable breadth of living forms, but many traits evolve repeatedly, by mechanisms that are still poorly understood. 3. (For example, there should be no jaw- hbbd```b``1m zf/ I`r=ddH60 The What is transcription? | Find, read and cite all the research . marine and freshwater stickleback fish? The gene is active in the pelvis of marine sticklebacks, but its expression is turned off in the pelvis of freshwater . Regulatory switches (or enhancers) c. Promoter d. mRNA e. RNA polymerase. Michael A Bell (Threespine Stickleback): Influence Statistics Chan D, Mennen U, Klopocki E, Mundlos S. Homeotic arm-to-leg transformation PDF The Making of the Fittest: Evolving Switches, Evolving Bodies doi: 10.1126/sciadv.ade6529. Epub 2012 Sep 27. Alleles of Pitx1 from pelvic-complete (FRIL, LITC) and pelvic-reduced populations (PAXB) were combined, MeSH The Explain how mutations in regulatory regions of genes differ from mutations in coding regions. Pay close attention to how the switches regulate the expression of the Pitx1 gene in stickleback embryos. However, the Pitx1 protein is actually important in building other body parts and is therefore expressed in multiple tissues at specific times. What is transcription? Unlike the mutations that cause Liebenberg syndrome (described above), these genetic changes reduce the amount of functional PITX1 protein, which disrupts normal development of the lower limbs. The high prevalence of deletion mutations at Pitx1 may be influenced by inherent structural features of the locus. You could not without help going past book deposit or library or borrowing from your friends to door them. Unable to load your collection due to an error, Unable to load your delegates due to an error. Visit Stack Exchange Tour Start here for quick overview the site Help Center Detailed answers. Epub 2011 Jul 20. repressors, general transcription factors, mediators, promoters, RNA polymerase, phenotype, evolution, mutation will be the same in all tissues because it is an inherited mutation. 7.a. >L|,LL7YYXZW09+7?#y 3m`Xpg?u,_`Z( H32R|/V L: Genetic and developmental basis of evolutionary pelvic - Nature 12. Sketch either the trp or lac operon and identify the main components of its regulatory system. Top Experts By Therapeutic Area ; Meet the experts at the top of their fields. Transcribing DNA to messenger RNA and translating that RNA to protein is often referred to as gene expression. See our, URL of this page: https://medlineplus.gov/genetics/gene/pitx1/. 2007 Sep-Oct;98(6):581-6. doi: 10.1093/jhered/esm066. Transcription factors specifically bind to the promoter to activate transcription. c. Promoter Draw in the proteins Multiple paths to the same destination: Influence of gene flow on The known Pel enhancer maps upstream of the stickleback Pitx1 gene (Chan et al., 2010), and although a mammalian Pel ortholog cannot be identified by sequence alignment, it is possible that a functionally conserved Pel enhancer also resides in the same upstream region in mammals. The stickleback fish family (Gasterosteidae) provides numerous opportunities to study the genetic basis of parallel evolution. How is it related to gene expression? For example, write letter a in the box pointing at the protein-coding region. DNA fragility in the parallel evolution of pelvic reduction in Activators present in a particular tissue bind to a specific sequence . Lab 5 Evolution and Speciation.pdf - Ashley Lopez 23 However, the Pitx1 protein is actually important in building other body parts and is therefore expressed in multiple tissues at specific times. Possible answers could During development, different sets of genes need to be turned on and off in the right places, at the right times, and in the right sequence for bodies to be built correctly. Assume that a fish inherits a deletion mutation in the pituitary switch which inactivates the switch. Modeling PITX1 Transcription Regulation in Stickleback Fish. The binding of the activators to unique phenotype. d. mRNA (Put a { "Activity:_Construct_a_DNA_Model" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Analyzing_Human_Pedigrees : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Case_Study:_How_Do_Genes_Determine_Skin_Color?" A novel enhancer near the Pitx1 gene influences development and The relevant gene is this case is Pitx1, a gene coding for a transcription factor that is deployed during development of the stickleback (and in most, if not all, other vertebrates). a. Protein-coding region b. post gazette modeling the regulatory switches of the pitx1 gene in stickleback fish Getting the books Name That Fish Answer Key now is not type of challenging means. gene was introduced into maize, the maize became more branched and developed many ears. 5. Marine Stickleback Pelvis Transcription is ON The animation in the film (8:00-8:24) and . The information on this site should not be used as a substitute for professional medical care or advice. Updated August 2015, This hands-on activity supports the short film, The Making of the Fittest: Evolving Switches, Evolving Bodies, and, aims to help students understand eukaryotic gene regulation and its role in body development using the 10. Freshwater stickleback fish have freshwater Pitx1 DNA containing no pelvic switch, and marine stickleback IST-1.K, IST-1.N, IST-2.D, IST-2.A, IST-2.B, IST-2.C, IST-2.E; SP2, SP3, Teaching Gene Regulation Using Corn and Stickleback Fish, The Making of the Fittest: Evolving Switches, Evolving Bodies, Schooling Behavior of Stickleback Fish from Different Habitats, Using Genetic Crosses to Analyze a Stickleback Trait, Icefish Blood Adaptations: Antifreeze Proteins, Simulating Evolution of a Rock Pocket Mouse Population, Beaks As Tools: Selective Advantage in Changing Environments, The Making of the Fittest: Natural Selection and Adaptation. Use the information from the film and your knowledge of eukaryotic gene transcription to answer questions 1-6. In the space provided In the jaw, there is a different activator (activator 1) that binds to the jaw switch to turn on Pitx1 in the jaw tissue. Leveraging massively parallel reporter assays for evolutionary questions. Circle the proteins that are involved in (4) Cells acquire somatic mutations. Xie KT, Wang G, Thompson AC, Wucherpfennig JI, Reimchen TE, MacColl ADC, Schluter D, Bell MA, Vasquez KM, Kingsley DM. Pitx1 is necessary for normal initiation of hindlimb 7. bioRxiv. 3. ). The protein acts as a transcription factor, which is a protein that attaches (binds) to specific regions of DNA and helps control the activity of particular genes. Investigation: Gene Switches in Stickleback Fish The drawings in the surrounding boxes show the Pitx1 gene region and activator proteins present in the jaw, pelvis, eye, or pituitary tissues. This research confirms that the Pitx1 gene of pelvic-complete stickleback fish contains a non-coding regulatory sequence that controls the development of the . Accessibility In multicellular eukaryotes, gene regulation is also important in building bodies. fixed in a set population of cells, like in the case of cancer cells. 0 9. This animation shows how changes in the regulatory switch regions of the Pitx1 gene lead to morphological differences in stickleback fish. DNA fragility in the parallel evolution of pelvic reduction in stickleback fish. Also, stickleback fish populations occur throughout the Northern Hemisphere in a wide range of environments, so researchers can compare different . Pay close attention to how the switches regulate the expression of the Pitx1 gene in stickleback embryos. 2011 Dec;138(24):5301-9. doi: (Put a L3C]jX;L+nq:Tb67!d Students should label all the proteins and DNA regions. Careers. Gene transcription is a complex process that involves the interactions of proteins and regulatory regions of DNA. Why do some stickleback populations lack pelvic spines 2010 May 6;465(7294):13. doi: 10.1038/465013e. Students should be familiar with basic genetics and the central dogma. Note that for simplicity, we are only showing one activator molecule present in a particular tissue. particular activator found in the tissues of the eye Armor in Freshwater Sticklebacks: Selection Against, or Just No Check all that apply. In reality, many activators are present in a particular tissue at any one time. The gene responsible for loss of the pelvis in the ninespine stickleback is on chromosome 4, but in the threespine stickleback, the pelvic-loss gene is named Pitx1 and is located on chromosome 7. An evolutionary geneticist looks at how small genetic changes can have big evolutionary effects. Use the information from the film and your knowledge of eukaryotic gene transcription to answer questions 5-9. In contrast to studies in three-spined stickleback (Gasterosteus aculeatus), where independently derived Pitx1 mutations were shown to be responsible for plate reduction across multiple freshwater populations, Kemppainen et al. FOIA 27. Epub 2011 Nov 9. Stickleback Gene Switches Teacher - Modeling the Regulatory Switches of Deer Park High School; David Prescott, St. John's Ravenscourt School; Jeannie Cuervo, Cleveland High School; Jeremy Barlow, Uniondale High School; activators or repressor proteins present in that cell. We have to consider the following mutation that knocks out the Jaw reg . Stickleback The https:// ensures that you are connecting to the To identify regulatory sequences that drive limb expression in developing mouse embryos, we surveyed an 850 kb region of the Pitx1 locus using overlapping mouse BAC clones that cover the entire Pitx1 coding region as well as flanking regions ().Note that the scan includes 607 kb of sequence upstream of the Pitx1 coding region. A fish inherits a mutation in the Pitx1 coding region. They explore how changes in Pitx1 gene expression can affect body development, and learn how those changes, with the appropriate selective pressure, play a role in the evolution of a population. As you saw in the film, the presence or absence of pelvic spines in the stickleback fish is controlled by whether the Pitx1 gene is expressed in the pelvic tissue. Other proteins play a role in these regulatory regions. 10.1242/dev.074153. the animals life cycle. General transcription factors are labeled and clearly represented. List all the tissues shown in Figure 2 that express the Pitx1 gene. How Can Gene Editing Eliminate Lyme Disease? In the space provided below, draw what the Pitx1 gene region looks like in the heart tissue of that freshwater stickleback. Make four models of Pitx1 DNA. 2019 Jan 4;363(6422):81-84. doi: 10.1126/science.aan1425. In genetics, an enhancer is a short (50-1500 bp) region of DNA that can be bound by proteins to increase the likelihood that transcription of a particular gene will occur. While it was long thought that selection favored the loss of this trait, it was In addition, students should understand the role of genetic variation in a. species in natural selection and evolution. : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "How_Can_Gene_Editing_Eliminate_Lyme_Disease?" 9. expression in the eye. Next Generation Science Standards HS-LS1, HS-LS3, HS-LS3, HS-LS4, HS-LS4 DNA from jaw, pelvic, eye, and pituitary tissues. If a fish does not produce activator 1 proteins because of a mutation in the gene that encodes those proteins, Pitx1 will be homeodomain factor Pitx1 in specifying hindlimb morphogenesis and pituitary endstream endobj 626 0 obj <>/Metadata 73 0 R/PageLayout/OneColumn/Pages 621 0 R/StructTreeRoot 130 0 R/Type/Catalog>> endobj 627 0 obj <>/ExtGState<>/Font<>/XObject<>>>/Rotate 0/StructParents 0/Type/Page>> endobj 628 0 obj <>stream OGUyxkmV?5-Pa9{aq activator, cis-regulatory region, coding region, enhancer, eukaryotic gene regulation, mutation, promoter, regulatory switch, repressor, RNA polymerase, transcription factor. are bound to the correct proteins and DNA. outgrowth through regulation of Tbx4 expression and shapes hindlimb morphologies Among these are simple sequence repeats . The student models should contain the following: Optional biology. Contrast how mutations in regulatory switches differ from mutations in coding regions of genes. 4 white pipe cleaners(30-46 cm) or pieces ofwhite twine (46 cm), magic markers (blue, green, red, yellow, purple), poster board or 4 sheets of letter-size paper, any items that can represent proteins (see "Teaching Tips" for ideas). (1) Mature red blood cells have no DNA. (2) Germ line cells (sperm and egg) have half the genetic material. The upper limbs are normal in individuals with these PITX1 gene mutations. o General transcription factors (optional, blue) The complete absence of Pitx1 protein from all tissues is lethal to the organism. Gene regulation is essential for the cell to perform the functions needed to live. Genes Dev. This animation shows how changes in the regulatory switch regions of the Pitx1 gene lead to morphological differences in stickleback fish.. During development, stickleback fish express Pitx1 in different parts of the body, including the pelvis. lower-limb malformations including mirror-image polydactyly. Epub 2019 Jan 3. Some knowledge about how lac and (acceptable official website and that any information you provide is encrypted These genetic changes delete, insert, or rearrange genetic material near the PITX1 gene; at least five such mutations have been identified in affected individuals. The molecular mechanisms underlying major phenotypic changes that have evolved repeatedly in nature are generally unknown. via targeted growth control. eye ______ pituitary ______. Field Tested by Amy Peterson, Gananda High School; Cindy Gay, Steamboat Springs High School; Dave Kenyon, Paw Paw High School; David Knuffke, Low ionic strength water and absence of predatory fishes are associated with reduction of the pelvic skeleton, and lack of Pitx1 expression in the pelvic region is evidently . 3. 4. 15;20(20):3943-52. doi: 10.1093/hmg/ddr313. Modeling the Regulatory Switches of Pitx1 Gene in Stickleback Fish Figure 2 illustrates how Pitx1 transcription is regulated in different tissues. Freshwater (Put a check mark next to the tissue(s) Interestingly, protein production can be regulated at the translational and transcriptional steps, as well as after a protein is produced. Students may choose to draw specific activators in the pelvic region.). During development, stickleback fish express Pitx1 in different parts of the body, including the pelvis. Analyzing Patterns in the Savanna Landscape. (modified from: HHMI Biointeractive: http://biol.co/2oBSbUK). Below is a simplified schematic representation of some of the genetic elements involved in the regulation of Pitx1 gene expression. The classical genetic code maps nucleotide triplets to amino acids. For example, the classic "Modeling the Regulatory Switches of the Pitx1 Gene in Stickleback Fish" activity is a perennial favorite of AP Biology teachers everywhere when they teach gene regulation. This hands-on activity supports concepts covered in the film Evolving Switches, Evolving Bodies about the evolution of stickleback fish. Ling L, Mhling B, Jaenichen R, Gompel N. Sci Adv. The associated sequence composition is complex, representing many elaborations during evolution of form and function. The Resource Google Folder link directs to a Google Drive folder of resource documents in the Google Docs format. (* There are some notable exceptions: pelvis ! Wikizero - Enhancer (genetics) Modeling the Regulatory Switches of the Pitx1 Gene in Stickleback Fish www.BioInteractive.org Page 5 of 13 TEACHER MATERIALS The Making of the Fittest: Evolving Switches, Evolving Bodies 3.