Correlations to Texas Essential Knowledge and Skills: Biology (7) Science concepts. The student knows the theory of biological evolution. The student is expected to: (A) identify evidence of change in species using fossils, DNA sequences, anatomical similarities, physiological similarities, and embryology; and (2) Scientific processes. The student uses scientific methods during field and laboratory investigations. The student is expected to: (C) organize, analyze, evaluate, make inferences, and predict trends from data; and (D) communicate valid conclusions. Purpose: The purpose of this station is to review and reinforce students understanding of the evidence of change in species using anatomical similarities. Note: Text with a line through it indicates this part of the TEKS is not being addressed in this activity. Some TEKS statements printed here end with a; or and and nothing thereafter this indicates that further TEKS statements follow but are not included here. Teacher Notes About the TEKS In middle school, students learn that a species traits can change over several generations as a result of natural selection and selective breeding. Students investigate how particular traits may enhance species survival and reproduction and how different environments support different varieties of organisms. In the last year of middle school, students come to recognize that changes in environmental conditions can also affect the survival of species. Students are expected to apply these middle school concepts to study biological evolution, including its formal definition, in Biology. Background Information for the Teacher Biological evolution can be measured as the change in frequency of alleles within a gene pool over a succession of generations. These changes, due primarily to mutations, gene shuffling that takes place during sexual reproduction, or chromosome synapsis and crossover during the early phases of sex cell production, can be exhibited as physical or biochemical. Evidence for the changes in allele frequency can be found through analysis of DNA sequences and examination of anatomical similarities, physiological similarities, and fossil records. The most reliable methods for determining evolutionary relationships are the analyses of Charles A. Dana Center at The University of Texas at Austin 1
physiological similarities and DNA sequences. The more similar the DNA sequences are, the more likely it is that the organisms share similar physiology. The fossil record, however incomplete, may also provide important information about the evolutionary history of an organism. Although anatomical similarities can serve as important evolutionary indicators, it is important to recall that some similarities are the result of common environmental factors rather than biological evolution. Analogous structures are anatomical similarities in different species that are the result of adaptations to environmental factors. Homologous structures are those anatomical similarities seen in different species that are a result of common ancestry. A cladogram is a commonly used method for phylogenetic analysis. The basic idea of a cladogram is to group members that share a common evolutionary history. Each subsequent species on a branch of a cladogram possesses a mixture of primitive characteristics that existed in the common ancestor along with newly evolved characteristics. Resources Lenski, Richard E. Evolution: Fact and Theory. ActionBioscience.org. www.actionbioscience.org/evolution/lenski.html. (Date retrieved: August 24, 2007.) Copyright 2000 2007, American Institute of Biological Sciences. Vavala, Phil. Evolution Simulation. Access Excellence at the National Health Museum. www.accessexcellence.org/ae/sh/nsta_nor/vavala_evol.html. (Date retrieved: August 24, 2007.) Copyright @ Access Excellence @ The National Health Museum. Whale Evolution. Evolution Library. WGBH Educational Foundation, www.pbs.org/wgbh/evolution/library/03/4/l_034_05.html. (Date retrieved: August 24, 2007.) Copyright 2001, WGBH Educational Foundation and Clear Blue Sky Productions, Inc. Materials Except for the question card, all materials are included in the blackline masters for this station. Whale skeleton cards DNA sequence cards DNA sequence cladogram Horse evolution station mat Horse evolution cards Station information sheet Student pages, including a glossary Question card (see Advance Preparation) Advance Preparation 1. Copy, cut, and laminate the whale skeleton cards, horse evolution cards, and DNA sequence cards included in the blackline masters. Charles A. Dana Center at The University of Texas at Austin 2
2. For each student, copy the DNA sequence cladogram, horse evolution station mat, student pages, and station information sheet; for the station table, make a copy of the DNA sequence cladogram, horse evolution station mat, and station information sheet. 3. Make a question card using question 52 from the Released TAKS Test for Exit Level Science, July 2004. This released test can be found at www.tea.state.tx.us/ student.assessment/resources/release/taks. Station Setup 1. Place the pictures of the whale skeletons, DNA sequence cards and cladogram, and horse evolution cards and station mat at the station table. 2. Tape a copy of the station information sheet to the table. Students will use this to confirm the station is set up correctly. Procedures 1. When students arrive at the station, they should check the station setup against the station information sheet at the table. If anything is missing or out of place, the students should notify the teacher. 2. Students should read the procedures in the student pages and answer the questions. Guide to Student Responses Focus Question: What information can be gained by examining fossil remains of the ancestors of modern organisms? Scientists can determine how closely related fossil organisms are to modern species by studying fossil remains. They can also predict what the environmental conditions were like where the fossil organisms lived. Questions 1. Sequence the whale skeleton cards in order from the oldest fossil to the most recent skeleton. Justify your answer. Rodhocetus balochistanensis, Ambulocetus natans, Orcinus orca The fossils progress from a walking whale with front and hind legs (Rodhocetus balochistanensis), to a whale with shorter front legs and outstretched hind legs (Ambulocetus natans), to the most recent skeleton of a modern whale with flippers and no hind legs (Orcinus orca). 2. What do the fossil remains of earlier whales indicate about changes in the whale s habitat over time? The fossil remains show whales with legs, feet, and a pelvis. These are all indicators that these organisms walked on land. Charles A. Dana Center at The University of Texas at Austin 3
3. If two different species have homologous structures, what can you tell about their evolutionary history? If two different species have homologous structures, they must share a common ancestor. 4. Locate the DNA sequence cards at the station. Place the shark, camel, and dolphin sequence cards in the appropriate spaces on the cladogram. Examine the DNA sequences on the remaining cards and compare them to the shark, dolphin, and camel cards. Determine the correct position of each of the remaining cards and place them on the cladogram. (The more closely the DNA sequences match, the more closely related the organisms are to each other.) Record the order of the sequence cards on your copy of the cladogram. 5. Examine the DNA sequence cladogram and determine which organisms are most closely related based on their homologous structures. Justify your answer. The shark and perch streamlined body shape and fins (dorsal, lateral, and caudal). The whale and dolphin streamlined body shape and fins (dorsal, lateral, and caudal). The similar body shapes and structures are the result a common ancestor shared by each pair. 6. Sometimes organisms that do not have a common ancestor may have anatomical similarities. These are called analogous structures. Examine the cladogram and Charles A. Dana Center at The University of Texas at Austin 4
determine which organism(s) share analogous structures with the perch and shark. Describe the analogous structure(s) and explain why these similarities could exist in organisms that do not share a common ancestor. The whale and dolphin share analogous structures with the perch and shark. They have similar fins and streamlined bodies because all of them live in water and swim. 7. Examine the cards that represent the evolution of the modern horse. Arrange the cards on the horse evolution station mat to show changes that have occurred in the anatomy of the horse from its most ancient ancestor to modern horses. Explain why you arranged the cards in the order you selected. 8. Examine your completed chart that now shows evolutionary changes that have occurred in the horse s anatomy over time. Describe the major changes that you observe. All parts of the horse s anatomy have become larger, the face is longer, and the cheek teeth have changed in number and size. The lower leg and feet have changed; the number of toes has been reduced from four smaller toes to one large toe that we now call the hoof. Charles A. Dana Center at The University of Texas at Austin 5
Blackline Masters for Contents: Station information sheet (1 copy for station table and 1 for each student) Whale skeleton cards (1 set for station table) DNA sequence cards (1 set for station table) DNA sequence cladogram (1 copy for station table and 1 for each student) Horse evolution station mat (1 copy for station table and 1 for each student) Horse evolution cards (1 set for station table) Student pages (1 copy for each student) Glossary (1 copy for each student) Charles A. Dana Center at The University of Texas at Austin 6
Station Information Sheet Charles A. Dana Center at The University of Texas at Austin 7
Whale Skeletons Rodhocetus balochistanensis (Balochistan walking whale) Ambulocetus natans (Walking whale) Orcinus orca (Killer whale) Charles A. Dana Center at The University of Texas at Austin 8
Charles A. Dana Center at The University of Texas at Austin 9
Charles A. Dana Center at The University of Texas at Austin 10
Hyracotherium Early Eocene Horse Evolution Station Mat Mesohippus Merychippus Pliohippus Oligocene L ate Miocene Pliocene Equus Pleistocene Charles A. Dana Center at The University of Texas at Austin 11
Charles A. Dana Center at The University of Texas at Austin 12
Student Pages Before You Begin Check to see that all the items are present and organized according to the station information sheet. If you notice a problem, notify the teacher immediately. Materials Station information sheet Whale skeleton cards DNA sequence cards DNA sequence cladogram Horse evolution station mat Horse evolution cards Glossary Focus Question: What information can be gained by examining fossil remains of the ancestors of modern organisms? Procedures 1. Discuss the focus question with your teammate(s) and record your answer. 2. Use the DNA sequence cards and cladogram, horse evolution cards and station mat, and the whale skeleton cards to answer the questions that follow. Charles A. Dana Center at The University of Texas at Austin Student Page 1
Questions 1. Sequence the whale skeleton cards in order from the oldest fossil to the most recent skeleton. Justify your answer. 2. What do the fossil remains of earlier whales indicate about changes in the whale s habitat over time? 3. If two different species have homologous structures, what can you tell about their evolutionary history? 4. Locate the DNA sequence cards at the station. Place the shark, camel, and dolphin sequence cards in the appropriate spaces on the cladogram. Examine the DNA sequences on the remaining cards and compare them to the shark, dolphin, and camel cards. Determine the correct position of each of the remaining cards and place them on the cladogram. (The more closely the DNA sequences match, the more closely related the organisms are to each other.) Record the order of the sequence cards on your copy of the cladogram. Charles A. Dana Center at The University of Texas at Austin Student Page 2
5. Examine the DNA sequence cladogram and determine which organisms are most closely related based on their homologous structures. Justify your answer. 6. Sometimes organisms that do not have a common ancestor may have anatomical similarities. These are called analogous structures. Examine the cladogram and determine which organism(s) share analogous structures with the perch and shark. Describe the analogous structure(s) and explain why these similarities could exist in organisms that do not share a common ancestor. 7. Examine the cards that represent the evolution of the modern horse. Arrange the cards on the horse evolution station mat to show changes that have occurred in the anatomy of the horse from its most ancient ancestor to modern horses. Explain why you arranged the cards in the order you selected. 8. Examine your completed chart that now shows evolutionary changes that have occurred in the horse s anatomy over time. Describe the major changes that you observe. NOTE: Because other students are going to do the activity after you, be sure to put all the materials at the station back as you found them. Sometimes there will be materials that need to be renewed or replaced. If you need assistance or have any questions, ask your teacher. Charles A. Dana Center at The University of Texas at Austin Student Page 3
Question Card 1. Obtain the question card from your instructor. 2. Read the question and discuss the answer with your teammate(s). 3. Record the team s consensus in your study folder and justify your answer. 4. Record the team s answer on the instructor s diagnostic wall chart. I Need to Remember Complete this part AFTER the class discussion of the station. I need to remember... Charles A. Dana Center at The University of Texas at Austin Student Page 4
Glossary for Alleles Alleles are the alternative forms or variations of the same gene. Analogous structures Analogous structures are structures in different species that exhibit anatomical similarities as a result of adaptations to environmental factors. Anatomical Anatomical refers to the structure and organization of an organism. Cladogram A cladogram is a tree-like diagram showing evolutionary relationships between organisms. Evolution Evolution is the change in the traits of organisms or populations of organisms from generation to generation. Fossil A fossil is a mineralized remain or preserved impression of an organism that lived in a past geological time. Gene pool The gene pool includes all the genes of a species in a population. Homologous structures Homologous structures are structures in different species that exhibit anatomical similarities as a result of common ancestry. Physiological Physiological refers to the functions and biological processes of an organism. Charles A. Dana Center at The University of Texas at Austin Student Page 5