EXPLORING THE EVOLUTION OF HORSES IN RESPONSE TO CLIMATE CHANGE

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Mervin Lester
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1 Chewing on Change: EPLORING THE EVOLUTION OF HORSES IN RESPONSE TO CLIMATE CHANGE

2 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change Authors: Jennifer Broo, Jessica Mahoney Curriculum team: Julie Bokor, Sean Moran, Cheryl McLaughlin, Bruce MacFadden This project supported in part by the following: Frances C. and William P. Smallwood Foundation (curriculum development) Science Education Partnership Award, National Center for Research Resources, part of the National Institutes of Health - Grant No: 1 R25 RR A2 (curriculum development) National Science Foundation Grant : PIRE Ancient biodiversity and global change in the New World Tropics: A once-in-a-century opportunity along the Panama Canal (CT scanning of fossil teeth, photography support) For more information about this and other curriculum projects, visit du/. Chewing on Change is available at du/resources/created-by-cpet-curriculum-fellows/evolution/ Please direct inquiries to the Center for Precollegiate Education and Training at cpet@cpet.ufl. du University of Florida Center for Precollegiate Education and Training PO Box Yon Hall, Room 331 Gainesville, FL Phone Fax

3 Contents 2 AUTHORS NOTE 3 INTRODUCTION AND GENERAL TEACHER BACKGROUND INFORMATION 5 TIPS ABOUT THIS CURRICULUM 7 LESSON SUMMARIES 7 VOCABULARY 8 LESSON SEQUENCING GUIDE 9 NET GENERATION SUNSHINE STATE STANDARDS FLORIDA SCIENCE 10 ADVANCED PLACEMENT BIOLOGY ESSENTIAL KNOWLEDGE AND SCIENCE PRACTICES 11 NET GENERATION SCIENCE STANDARDS (NGSS) 52 CONTENT ASSESSMENT 56 CONTENT ASSESSMENT ANSWER KEY 57 MATE: MEASURE OF ACCEPTANCE OF THE THEORY OF EVOLUTION 58 STUDENT FEEDBACK FORMS 60 STUDENT DEMOGRAPHIC FORM 61 TEACHER IMPLEMENTATION FORM 63 TEACHER FEEDBACK FORM LESSON ONE 13 EPLORING THE GEOLOGIC TIME SCALE VIA CHANGES IN FOSSILIZED HORSE TEETH IN RESPONSE TO THE EVOLUTION OF PLANTS 17 TEACHER ANSWER KEY 18 EPOCH CARDS 23 STUDENT PAGES LESSON TWO 33 EAMINING INTRASPECIES VARIATION AND CHANGES IN A SINGLE HORSE POPULATION 36 TEACHER ANSWER KEY 37 HORSE TEETH IMAGES 38 STUDENT PAGES LESSON THREE 41 PROPOSING CHANGES TO ORTHOGENESIS AND COMMUNICATING EVOLUTION IN MUSEUM 44 HORSE CARDS 46 STUDENT PAGES 65 CONTENT EPERT EVALUATION FORM 67 Notes ABOUT THE COVER: Artist s reconstruction of Sifrhippus sandrae (right) touching noses with a modern Morgan horse (left) that stands about 5 feet high at the shoulders and weighs approximately 1000 lbs. Credit Illustration by Danielle Byerley, Florida Museum of Natural History CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change 1

4 Authors Note As biology teachers, we are familiar with the quote from Theodosius Dobzhansky: Nothing in biology makes sense except in the light of evolution. Despite the importance of evolution in biology, many students have difficulty with this topic and come to the classroom with negative perceptions of the theory of evolution. In addition, macroevolution takes place over such long time periods (apart from some bacteria and viruses) that the process can be hard for students to conceptualize and appear as a topic that is not relevant to their lives. We have also found that students struggle to understand natural selection. It is often taught as a list of rules or steps that students memorize, and therefore, they rarely internalize this important mechanism of evolution. Our hope is that by using a familiar organism, the horse, and engaging in the authentic practices of science including the opportunity to examine fossils, take measurements and make claims based on scientific evidence, students begin to appreciate the elegance and predicative power of evolutionary theory. The activities in this unit require no prerequisite understanding of evolution or vocabulary associated with evolution. We believe that by focusing on concepts and then presenting the information in a more formal way will result in greater student acceptance and understanding of evolution. We also believe this hands-on inquiry approach to introducing evolution will aide in students ability to apply what they learn about horse evolution to other areas of biology. 2 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change

Introduction and General Teacher Background Information The earliest known horses evolved 55 million years ago (Ma). Early horses were small dog-sized animals that lived in forests.

5 Introduction and General Teacher Background Information The earliest known horses evolved 55 million years ago (Ma). Early horses were small dog-sized animals that lived in forests. Throughout their 55 million year history horses have diverged into many species, several of which coexisted, particularly during the Miocene that had the highest diversity of species. Horses are part of the order Perissodactyla (odd-toed ungulates) which also includes tapirs and rhinoceroses. Horses are members of the Equidae family and modern day horses are members of the genus Equus, the only extant genus of the Equidae family. Other living members of the genus Equus include donkeys and zebras. Horse evolution is an excellent example of macroevolution (changes that occur at or above a species level) because so much fossil evidence has been found, including a great number of fossils from North America (MacFadden, 2005). Fossils provide physical evidence of changes that have occurred in organisms throughout long periods of time. Loose teeth last longer than any other skeletal part and as a result teeth have provided a great deal of information about horse evolution. Each fossil horse tooth has at least 50 different features that can be counted and measured (Sloan Lab). These measurements provide evidence of the macroevolution of horses. From Ma horses lived in forests, feeding on the soft forest leaves with short-crowned teeth. As the climate became cooler and drier, better-adapted grasses grew more successfully and grasslands began to cover more of the earth, replacing previously lush forests. Grasses have phytoliths (small pieces of silica and minerals) inside their cells, resulting in more tooth wear in grazing animals. In a grassland environment, high-crowned (long) teeth are an adaptation since longer teeth take more time to wear down (Darthmouth & Janis, 2011). Between Ma fossil evidence indicates tooth morphology diversified and the number of shortercrowned species that relied on soft leaves declined. During the same time period, other species of horses evolved high-crowned teeth that were better adapted to a grazing diet. Some of these high-crowned species also underwent further adaptation and evolved to eat a diet of both leafy plants and grasses. Around 7 million years ago The molars and premolars of the horse are known as cheek teeth. The cheek teeth slowly erupt to compensate for the constant grinding which wears away 2-3 mm per year. For this reason, horses have very long teeth that are referred to as hypsodont, or high tooth. grasslands underwent another change that affected horse evolution. In the last 7 million years tropical and temperate grasslands have shifted from mainly grasses that used the C 3 photosynthesis pathway to modern day grasslands that are composed mainly of grasses that use the C 4 photosynthetic pathway (MacFadden, 2005). Genetic diversity (which results in phenotypic variation) is the raw material for natural selection. Although paleontologists are usually limited to studying individual organisms, occasionally a dig site will have numerous individuals of the same species. For example, paleontologists at the University of Florida conducted a study of 80 individuals of the genus Parahippus found at Thomas Farm. Parahippus is the common ancestor at the branching point between Old World and New World horses. Fossilized teeth show variation in tooth structure CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change 3

Here, two large Dinohippus horses can be seen grazing on grass, much like horses today. But unlike modern horses, a three-toed Hypohippus tiptoes through the forest, nibbling on leaves.

6 Here, two large Dinohippus horses can be seen grazing on grass, much like horses today. But unlike modern horses, a three-toed Hypohippus tiptoes through the forest, nibbling on leaves. A small, three-toed Nannippus, shown here eating shrubs, ate both grass and leaves. Matt Shanley/AMNH within a species that can be measured and provide particularly useful data for examining variation within a population and learning more about the population ecology of the species (Hulbert, 1984). Although horses provide an excellent example of macroevolution, there are some misconceptions about horse evolution that need to be addressed with students. Over half of the natural history museums in the United States currently have exhibits that depict horse evolution as an orthogenic process. Orthogenesis is the concept that evolution occurs in a linear pattern with one species turning into another as evolution proceeds. This depiction reinforces the misconception that evolution results in more perfect organisms and is predestined. However, paleontologists have realized for decades horse evolution is more correctly depicted as a complex branching phylogeny (MacFadden, 2012). FOR FURTHER INFORMATION: American Museum of Natural History: MacFadden, B. J. (2005). EVOLUTION: Fossil Horses Evidence for Evolution. Science 307 (5716): doi: /science PMID MacFadden, Bruce J (2003 digitization of 1999 reprint). Fossil Horses: Systematics, Paleobiology, and Evolution of the Family Equidae. Cambridge & New York: Cambridge University Press. ISBN Hulbert, Richard C. (1984) Paleoecology and Population Dynamics of the Early Miocene (Hemingfordian) Horse Parahippus Leonensis from the Thomas Farm Site, Florida Journal of Vertebrate Paleontology, Vol. 4, No. 4. ( ) PBS Nature Horses, nature/episodes/horses/introduction/3153/ 4 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change

7 Tips about this Curriculum LESSON PLAN FORMAT All lessons in this curriculum unit are formatted in the same manner. In each lesson you will fi d the following components: KEY QUESTION(S) Identifies key questions the lesson will explore. OVERALL TIME ESTIMATE Indicates total amount of time needed for the lesson, including advanced preparation. LEARNING STYLES Visual, auditory, and/or kinesthetic. VOCABULARY Lists key vocabulary terms used and defi ed in the lesson. Also collected in master vocabulary list. LESSON SUMMARY Provides a 1-2 sentence summary of what the lesson will cover and how this content will be covered. Also collected in one list. STUDENT LEARNING OBJECTIVES Focuses on what students will know, feel, or be able to do at the conclusion of the lesson. STANDARDS Specific state benchmarks addressed in the lesson. Also collected in one list. MATERIALS Items needed to complete the lesson. Number required for different types of grouping formats (Per class, Per group of 3-4 students, Per pair, Per student) is also indicated. BACKGROUND INFORMATION Provides accurate, up-to-date information from reliable sources about the lesson topic. ADVANCE PREPARATION This section explains what needs to be done to get ready for the lesson. PROCEDURE WITH TIME ESTIMATES The procedure details the steps of implementation with suggested time estimates. The times will likely vary depending on the class. ASSESSMENT SUGGESTIONS Formative assessment suggestions have been given. Additionally, there is a brief summative assessment (pre-/post-test) that can be given. Teachers should feel free to create additional formative and summative assessment pieces. ETENSIONS (ACTIVITIES/LITERATURE) There are many activities and reading sources available to augment and enhance the curriculum. They have been included. If you fi d additional ones that should be added, please let us know. RESOURCES/REFERENCES This curriculum is based heavily on primary sources. As resources and references have been used in a lesson, their complete citation is included as well as a web link if available. All references and resources are also collected in one list. STUDENT PAGES Worksheets and handouts to be copied and distributed to the students. TEACHER PAGES Versions of the student pages with answers or the activity materials for preparation. COLLABORATIVE LEARNING The lessons in this curriculum have been developed to include many collaborative learning opportunities. Rather than presenting information in lecture format and teacher driven, the activities involve the students in a more engaged manner. For classrooms not accustomed to using collaborative learning strategies, have patience. It can be difficult to communicate instructions, particularly for students who are visual learners. For these students, use of visual clues such as flowcharts and graphics can help them understand how they are to move to different groups. CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change 5

8 GROUPS Some of these lessons are carried out in groups. While it is not necessary for students to remain in the same groups the entire unit, if they work well together, it may foster students to think deeper as they are comfortable with their teammates and willing to ask questions of each other. INQUIRY-BASED The lessons in the curriculum invite students to be engaged and ask questions. They work through background information in a guided fashion, but are challenged to think beyond what they have read or done. The teacher serves as the facilitator in these activities, not the deliverer of information. TECHNOLOGY Lessons have been written to be mindful of varying availability of technology in schools and homes. IMPLEMENTATION NOTES This curriculum should be modified and adapted to suit the needs of the teacher and students. The authors suggest that students have a basic understanding of the geologic time scale. An activity such as The Geologic Time Scale Lab (many versions of this activity using rolls of receipt paper are readily available online) would serve this purpose in approximately one additional instruction day. ETENSIONS Possible/recommended extension activities that can be completed in addition to the written curriculum are included. SCIENCE SUBJECT Biology GRADE AND ABILITY 9-12 grade Standard/Honors/Advanced Placement CONTENT Often we teach in a manner that is very content heavy. With high-stakes testing the norm, students are pushed to memorize and recall numerous isolated facts. There is so much content that must be covered in a biology class, for example, that often it is difficult to synthesize those discrete facts into a compelling context or a story. This unit provides the opportunity to introduce and explore the evolution of horses from both the macro and micro evolutionary levels using 3D printed models and digital images of actual fossil samples from the Florida Museum of Natural History (FLMNH). 6 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change

9 Lesson Summaries LESSON ONE EPLORING THE GEOLOGIC TIME SCALE VIA CHANGES IN FOSSILIZED HORSE TEETH IN RESPONSE TO THE EVOLUTION OF PLANTS As an opening activity the class is presented with a slide show of illustrations representing the physical landscape of each of the five epochs explored in this lesson. As a class students make observations about the types of flora present in each epoch. Next, in collaborative learning groups, students measure and sketch physical characteristics of fossilized horse teeth from a 3D printed study set provided by the FLMNH. Each group produces a graph that summarizes the trend between age of the fossil and hypsodonty index (HI, essentially the length of the tooth divided by the width). Plant information cards summarizing each epoch are also provided to each group and superimposed on the student graph. Guided analysis questions allow students to develop an explanation for the change in horse teeth in response to plant evolution. LESSON TWO Examining Intraspecies Variation and Changes in a Single Horse Population In this lesson students examine images of a collection of horse teeth from the same population. Students take HI measurement data (same procedure as Lesson One) to determine if this collection of teeth represents individuals from the same species. Students use the graphs produced in Lesson One to determine which species this population likely belonged to. Additionally, students determine if there is intraspecies variation in this population, using an embedded horse tooth variation guide in the student page: Examining Intraspecies Variation and Changes in a Single Horse Population. Finally, students make predictions as to what might happen to horse teeth in future generations if plant life drastically differed again on Earth. LESSON THREE Proposing Changes to Orthogenesis and Communicating Evolution in Museums Students are presented a current problem observed in the majority of natural history museums in which orthogenesis is used to display the evolution of horses. The use of orthogenesis, rather than the widely accepted branching phylogenetic tree, often leads to misconceptions about evolution amongst visitors of the general public to such exhibits (MacFadden et al, 2012). Teachers can provide students with a fictional letter from the curator of a natural history museum requesting their help with this problem or have students complete a close read of the paper by MacFadden and colleagues (2012) to explore this issue. Students then use their fossil data graphs from Lesson One in addition to information about ancestral horse species presented on horse cards to complete a poster proposal to summarize how the fossil records clearly show a branching phylogenetic evolution of the horse. VOCABULARY EPOCH: a period of time in history FOSSIL: Any preserved evidence of life from a past geological age, such as the impressions and remains of organisms embedded in stratified rocks GENETIC VARIATION: variation in alleles of genes, occurs both within and among populations. Genetic variation is important because it provides the genetic material for natural selection. INTRASPECIES: arising or occurring within a species; involving the members of one species INTERSPECIES: arising or occurring between species Morphology-the form and structure of an organism ORTHOGENETIC: the hypothesis that life has an innate tendency to evolve in a unilinear fashion due to some internal or external driving force. PALEONTOLOGIST: a person who studies forms of life existing in prehistoric or geologic times, as represented by the fossils of plants, animals and other organisms PLICATION: a fold or corrugation PHYLOGENETIC TREE: evolutionary tree, a branching diagram or tree showing the inferred evolutionary relationships among various biological species based upon similarities and differences in their physical or genetic characteristics CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change 7

10 LESSON SEQUENCING GUIDE Since the classroom teacher knows his or her students best, the teacher should decide the sequencing of lessons. The suggested sequencing guide below is based on 45 minute class periods. DAY 1 DAY 2 DAY 3 DAY 4 DAY 5 LESSON ONE: Exploring the Geologic Time Scale via Changes in Fossilized Horse Teeth in Response to Co-evolution of Plants LESSON ONE: Exploring the Geologic Time Scale via Changes in Fossilized Horse Teeth in Response to Co-evolution of Plants LESSON TWO: Examining Intraspecies Variation and Changes in a Single Horse Population LESSON THREE: Proposing Changes to Orthogenesis and Communicating Evolution in Museums (Optional Presentations) LESSON THREE: Proposing Changes to Orthogenesis and Communicating Evolution in Museums 8 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change

11 NET GENERATION SUNSHINE STATE STANDARDS FLORIDA SCIENCE BENCHMARK LESSON 1 LESSON 2 LESSON 3 SC.912.L.15.1 Explain how the scientific theory of evolution is supported by the fossil record, comparative anatomy, comparative embryology, biogeography, molecular biology, and observed evolutionary change. SC.912.L Describe the conditions required for natural selection, including: overproduction of offspring, inherited variation, and the struggle to survive, which result in differential reproductive success. SC.912.L Describe how mutation and genetic recombination increase genetic variation. SC.912.L.15.3 Describe how biological diversity is increased by the origin of new species and how it is decreased by the natural process of extinction. SC.912.L.15.4 Describe how and why organisms are hierarchically classified and based on evolutionary relationships. SC.912.N.1.1 Defi e a problem based on a specific body of knowledge SC.912.N.1.3 Recognize that the strength or usefulness of a scientific claim is evaluated through scientific argumentation, which depends on critical and logical thinking, and the active consideration of alternative scientific explanations to explain the data presented. SC.912.N.1.6 Describe how scientific inferences are drawn from scientific observations and provide examples from the content being studied. SC.912.N.3.1 Explain that a scientific theory is the culmination of many scientific investigations drawing together all the current evidence concerning a substantial range of phenomena thus, a scientific theory represents the most powerful explanation scientists have to offer. CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change 9

12 ADVANCED PLACEMENT BIOLOGY ESSENTIAL KNOWLEDGE AND SCIENCE PRACTICES ESSENTIAL KNOWLEDGE & SCIENCE PRACTICES LESSON 1 LESSON 2 LESSON 3 Essential knowledge 1.A.1: Natural selection is a major mechanism of evolution Essential knowledge 1.A.2: Natural selection acts on phenotypic variations in populations. Essential knowledge 1.A.3: Evolutionary change is also driven by random processes. Essential knowledge 1.B.2: Phylogenetic trees and cladograms are graphical representations (models) of evolutionary history that can be tested. Essential knowledge 1.C.1: Speciation and extinction have occurred throughout the Earth s history Essential knowledge 1.C.3: Populations of organisms continue to evolve. Science Practice 1: The student can use representations and models to communicate scientific phenomena and solve scientific problems. Science Practice 3: The student can engage in scientific questioning to extend thinking or to guide investigations within the context of the AP course. Science Practice 5: The student can perform data analysis and evaluation of evidence. Science Practice 6: The student can work with scientific explanations and theories. 10 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change

13 NET GENERATION SCIENCE STANDARDS (NGSS) HS-LS4-1. Communicate scientific information that common ancestry and biological evolution are supported by multiple lines of empirical evidence. LESSON 1 LESSON 2 LESSON 3 HS-LS4-4. Construct an explanation based on evidence for how natural selection leads to adaptation of populations. HS-LS4-5. Evaluate the evidence supporting claims that changes in environmental conditions may result in: (1) increases in the number of individuals of some species, (2) the emergence of new species over time, and (3) the extinction of other species. Crosscutting Concept 1. Patterns. Observed patterns of forms and events guide organization and classification, and they prompt questions about relationships and the factors that infl ence them. Crosscutting Concept 2. Cause and effect: Mechanism and explanation. Events have causes, sometimes simple, sometimes multifaceted. A major activity of science is investigating and explaining causal relationships and the mechanisms by which they are mediated. Such mechanisms can then be tested across given contexts and used to predict and explain events in new contexts. Crosscutting Concept 6. Structure and function. The way in which an object or living thing is shaped and its substructure determine many of its properties and functions. Crosscutting Concept 7. Stability and change. For natural and built systems alike, conditions of stability and determinants of rates of change or evolution of a system are critical elements of study CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change 11

14 Notes: 12 CHEWING ON CHANGE: Exploring the Evolution of Horses in Response to Climate Change

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