Chapter 15: the Theory of Evolution

Chapter 15 Organizer The Theory of Evolution

Refer to pages 4T-5T of the Teacher Guide for an explanation of the National Science Education Standards correlations. Teacher Classroom Resources Activities/FeaturesObjectivesSection MastersSection TransparenciesReproducible

Reinforcement and Study Guide, pp. 65-66 L2 Section Focus Transparency 37 L1 ELL Section 15.1 1. Summarize Darwin’s theory of natural MiniLab 15-1: Camouflage Provides an Section 15.1 selection. Adaptive Advantage, p. 406 Concept Mapping, p. 15 L3 ELL Natural Selection and 2. Explain how the structural and physio- Problem-Solving Lab 15-1, p. 407 Natural Selection Critical Thinking/Problem Solving, p. 15 L3 the Evidence for logical adaptations of organisms relate and the Evidence BioLab and MiniLab Worksheets, p. 71 L2 P Evolution to natural selection. for Evolution Laboratory Manual, pp. 103-108P L2 National Science Education 3. Distinguish among the types of evi- Content Mastery, pp. 73-74, 76 L1 Standards UCP.1-5; A.1, A.2; dence for evolution. P P C.3, C.4, C.6; F.4; G.1, G.3 P LS Reinforcement and Study Guide, pp. 67-68 L2 Section Focus Transparency 38 L1 ELL (2 sessions, 1 block) Section 15.2 LS P Critical Thinking/Problem Solving, p. 15 L3 Basic Concepts Transparency 21 L2 ELL Mechanisms of BioLab and MiniLab Worksheets,LS pp. 72-74P LSL2 Basic Concepts Transparency 22 L2 ELL Section 15.2 4. Summarize the effects of the different MiniLab 15-2: Detecting a Variation, p. 415 Evolution Content Mastery, pp. 73, 75-76 L1P LS Reteaching Skills Transparency 24 L1P ELL types of natural selection on gene pools. Internet BioLab: Natural Selection and LS P Mechanisms of 5. Relate changes in genetic equilibrium to Allelic Frequency, p. 422 Assessment Resources Additional Resources P Evolution mechanisms of speciation. Math Connection: Mathematics and P LSP P P National Science Education 6. Explain the role of natural selection in Evolution, p. 424 Chapter Assessment, pp. 85-90 LS Spanish Resources ELL LS Standards UCP.1-5; A.1, convergent and divergent evolution. P MindJogger Videoquizzes English/Spanish Audiocassettes ELL P LS A.2; C.1-4, C.6; F.4; G.1-3 P P Performance Assessment in the Biology Classroom Cooperative Learning in the Science Classroom LS (3 sessions, 2 blocks) LS LS COOP LEARN Alternate Assessment in the Science Classroom LessonLS Plans/Block SchedulingP LS Computer Test Bank P P LS P BDOL Interactive CD-ROM, Chapter 15 quiz LS LS Need Materials? Contact Carolina Biological Supply Company at 1-800-334-5551 KeyKey toto TeachingTeaching StrategiesStrategies or at http://www.carolina.com LS L1 Level 1 activities should be appropriate LS MATERIALS LIST for students with learning difficulties. LS LS LS L2 Level 2 activities should be within the BioLab Alternative Lab ability range of all students. Teacher’s p. 422 colored pencils (2), paper bag, p. 414 culture of Bacillus subtilis, 3 L3 Level 3 activities are designed for above- graph paper, pinto beans, white navy tubes of nutrient agar, tube of strepto- average students. Corner beans mycin agar, inoculation loop, petri The following multimedia resources are available from Glencoe. ELL ELL activities should be within the ability Products Available From Index to National dishes (2), Bunsen burner, wax pencil, range of English Language Learners. Biology: The Dynamics of Life MiniLabs National Geographic Society Geographic Magazine test tube CD-ROM ELL COOP LEARN Cooperative Learning activities To order the following products, The following articles may be p. 406 hole punch, paper, white and P are designed for small group work. Video: Galapagos Quick Demos P call National Geographic Society used for research relating to this black P Video: Adapted for Survival P These strategies represent student prod- at 1-800-368-2728: chapter: p. 415 ruler, unshelled peanuts (30) p. 402 photographs of automobile ucts that can be placed into a best-work Exploration: The Record of Life P Book “The Dawn of Humans: P P model portfolio. Exploration: Selection Pressure National Geographic Atlas of Redrawing Our Family Tree?” by p. 418 overhead projector LS These strategies are useful in a block LS World History Lee Berger, August 1998. Videodisc Program LS scheduling format. LS “Dinosaurs Take Wing,” by Geographic Isolation LS Jennifer Ackerman, July 1998. AdaptedLS for SurvivalLS “A Curious Kinship: Apes and The Infinite Voyage Humans,” by Eugene Linden, The Great Dinosaur Hunt May 1992. The Secret of Life Series It’s in the Genes: Evolution Camouflage: Caterpillars Camouflage: Spider Horse Evolution Patterns of Descent Gone Before You Know It: The Biodiversity Crisis

400A 400B ChapterChapter 1515 ChapterChapter SECTION PREVIEW Section Objectives Section 15.1 Summarize Darwin’s theory of natural 15.1 Natural Selection and the selection. ETTING TARTED EMO The Theory of Evolution GETTING STARTED DEMO 15 Explain how the Prepare Evidence for Evolution structural and physio- Kinesthetic Blindfold a logical adaptations of organisms relate to Key Concepts student volunteer. Then natural selection. place a couple of small, familiar What You’ll Learn ou need only to look around Students will study Charles you to see the diversity of Distinguish among objects, such as a stapler and a You will analyze the theory the types of evidence Darwin’s concept of natural of evolution. Yorganisms on Earth. About for evolution. selection. They will also learn pen, on a desk and ask the vol- You will compare and 150 years ago, Charles Darwin, unteer to identify the objects. Vocabulary about scientific evidence that contrast the processes who had studied an enormous Point out to the class that some artificial selection supports the theory of evolution. of evolution. variety of life forms, proposed an natural selection organisms that live in dark caves mimicry idea to explain how organisms successfully use senses other Why It’s Important camouflage Planning homologous structure P Evolution is a key concept probably change over time. than sight to monitor their envi- analogous structure Collect photos of automobiles for understanding biology. Biologists still base their ronments. L1 ELL vestigial structure Evolution explains the diversity work on this idea because for the Quick Demo. embryo of species and predicts changes. it explains the living Purchase pinto beans for the world they study. Project. LS Theme DevelopmentP GETTING STARTED Obtain black and white con- The unity within diversity Identifying Variation struction paper and paper theme is apparent in this chapter. All populations have variations. punches for MiniLab 15-1. The theme of evolution is also Hypothesize the most common An Asian leopard Obtain bird bones (chicken, eye color in your class. Now test and a cheetah (inset) evident. The theoryLS of evolution turkey, quail) for the Display. this hypothesis. Gather photos of a variety of can explain P the diversity of organisms. To find out organisms for the Activity. more about evolution, visit the Glencoe Scientists wondered how fossils Science Web Site. Charles Darwin and formed, why many fossil species were www.glencoe.com/sec/science LS Natural Selection extinct, and what kinds of relation- 1 Focus If time does not permit teach- The modern theory of evolution is ships might exist between the extinct ing the entire chapter, use the a fundamental concept in biology. and the modern species. Bellringer BioDigest at the end of the Recall that evolution is the change in When geologists provided evi- Before presenting the lesson, unit as an overview. populations over time. Learning the dence indicating that Earth was display Section Focus Trans- principles of evolution makes it easier much older than many people had parency 37 on the overhead pro- to understand modern biology. One originally thought, biologists began jector and have students answer place to start is by learning about the to suspect that life slowly changes This crayfish (above) and cricket the accompanying questions. ideas of English scientist Charles over time, or evolves. Many explana- (inset) live in dark caves and are L1 ELL blind. They have sighted rela- Darwin (1809–1882)—ideas sup- tions about how species evolve have tives that live where there is ported by fossil evidence. been proposed, but the ideas first light. Both the cave- published by Charles Darwin are the Fossils shape ideas dwelling species and their basis of modern evolutionary theory. TransparencyP 37 Camouflage SECTION FOCUS Use with Chapter 15, relatives are adapted to about evolution Section 15.1 different environments. As Biologists have used fossils in their Darwin on HMS Beagle populations adapt to new or changing environments, work since the eighteenth century. In It took Darwin years to develop his individuals in the popula- fact, fossil evidence formed the basis theory of evolution. He began in LS tion that are adapted success- of the early evolutionary concepts. 1831 at age 21 when he took a job as fully survive. P

400 THE THEORY OF EVOLUTION 15.1 NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION 401

Snowshoe hare AssessmentAssessment PlannerPlanner LS in summer Look for the following logos for strategies that emphasize different learning modalities. Portfolio Assessment Knowledge Assessment Multiple Kinesthetic Getting Started Linguistic Portfolio, pp. 402, Snowshoe hare in winter Portfolio, TWE, pp. 402, 406, 407, 410, 420 MiniLab, TWE, p. 406 1 What is the advantage of this snowshoe hare’s seasonal color change?

Demo, p. 400; Visual Learning, 406, 407; Meeting Individual Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. Assessment, TWE, pp. 411, 419 Problem-Solving Lab, TWE, p. 407 2 The adaptation that allows an animal to blend in with Learning its environment is called camouflage. What examples p. 413 Needs, pp. 403, 419; Biology Journal, MiniLab, TWE, p. 415 Alternative Lab, TWE, p. 415 of camouflage are you familiar with? Styles Visual-Spatial Reteach, p. 421 pp. 405, 413, 416; Extension, p. 421 Performance Assessment BioLab, TWE, p. 423 BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES Logical-Mathematical Project, Assessment, TWE, pp. 403, 408 Section Assessments, SE, pp. 411, 421 Interpersonal Project, pp. 408, p. 404; Portfolio, p. 410; Tech MiniLabs, SE, pp. 406, 415 Chapter Assessment, SE, pp. 425-427 417; Activity, p. 411 Prep, p. 412; Reinforcement, p. 416 Alternative Lab, TWE, pp. 414-415 Skill Assessment Intrapersonal Reteach, p. 410 Naturalist Meeting Individual BioLab, SE, pp. 422–423 Assessment, TWE, p. 421 400 Needs, p. 409 401 Concept Development a naturalist on the English ship HMS observations that Darwin made and Finally, English economist Thomas Figure 15.2 2 Teach Beagle, which sailed to South America the specimens that he collected there Malthus proposed an idea that Darwin Darwin proposed the idea of natural selection Before Darwin developed his and the South Pacific on a five-year were especially important to him. modified and used in his explanation. to explain how species change over time. theory of evolution by natural Quick Demo scientific journey. On the Galapagos Islands, Darwin Malthus’s idea was that the human selection, French biologist Jean- As the ship’s naturalist, Darwin studied many species of animals and population grows faster than Earth’s A In nature, organ- Baptiste de Lamarck (1744- isms produce more Use a photo series of an auto- studied and collected biological speci- plants, Figure 15.1, that are unique food supply. How did this help 1829) proposed a different mech- mens at every port along the route. to the islands, but similar to species Darwin? He knew that many species offspring than can mobile model that shows how anism for evolutionary change. As you might imagine, these speci- elsewhere. These observations led produce large numbers of offspring. survive. Fishes, for that model has changed over example, can some- Lamarck’s idea rested on two mens were quite diverse. Studying Darwin to consider the possibility He also knew that such species had time. Alternatively, show a pic- times lay millions assumptions: (1) the more an the specimens made Darwin curious that species can change over time. not overrun Earth. He realized that of eggs. ture of an early automobile organism uses a part of its body, Figure 15.1 about possible relationships among However, after returning to England, individuals struggle to survive. There the more that part develops, and and one of a modern automo- The five-year voyage species. His studies provided the he could not at first explain how such are many kinds of struggles, such as bile. Have students explain (2) the physical characteristics of HMS Beagle took foundation for his theory of evolu- changes occur. competing for food and space, escap- that an organism develops in this how automobiles are the same Darwin around the tion by natural selection. ing from predators, finding mates, and way can be passed to offspring. and how they have changed world. Animal species Darwin continues his studies locating shelter. Only some individu- in the Galapagos Discuss Lamarck’s hypothesis over time. Then, point out that Darwin in the Galapagos For the next 22 years, Darwin als survive the struggle and produce Islands have unique B In any population, with students, asking them to list organisms also change over The Galapagos (guh LAHP uh gus) worked to find an explanation for offspring. Which individuals survive? adaptations. individuals have its weaknesses. time. Ask students to distin- Islands are a group of small islands how species change over time. He Darwin gained insight into the variations. Fishes, guish between the two kinds near the equator, about 1000 km off read, studied, collected specimens, mechanism that determined which for example, may of evolution. The changes in A The beak of this the west coast of South America. The and conducted experiments. organisms survive in nature from differ in color, size, Visual Learning Galapagos finch is and speed. automobiles or a specific auto- his pigeon-breeding experiments. Figure 15.2 shows the four prin- P adapted to feed Darwin observed that the traits of mobile model occur faster than on cacti. B Galapagos tortoises are cipal ideas of natural selection. changes in organisms. the largest on Earth, dif- individuals vary in populations—even Discuss each principle to rein- fering from other tortoises in a population of pigeons. Sometimes force the ideas. Provide other in body size and shape. variations are inherited. By breeding examples of natural selection, pigeons with desirable variations, LS using alternative organisms and Concept Development Darwin produced offspring with these ARCTIC OCEAN habitats, to review the concept. A significant influence on variations. Breeding organisms with C Individuals with certain useful varia- Darwin’s thinking was the book specific traits in order to produce off- spring with identical traits is called tions, such as The Principles of Geology by speed, survive in Assessment Charles Lyell. This book pro- artificial selection. Darwin hypoth- their environment, esized that there was a force in nature Performance Assessment posed that Earth is very old and ASIA passing those that worked like artificial selection. variations to the in the Biology Classroom, p. 23, NORTH ATLANTIC EUROPE that the forces that have pro- OCEAN AMERICA next generation. Investigating Variations in Popu- duced changes on Earth’s surface Azores Darwin explains natural selection lations. Have students carry out in the past are the same ones Canary PACIFIC Islands OCEAN Using his collections and observa- this activity to explore what varia- that continue to operate today. Cape Verde tions, Darwin identified the process of tions occur in a population. L2 Galapagos Islands AFRICA Discuss how Darwin was influ- Islands natural selection, the steps of which you enced by other ideas of his day. Lima Bahia INDIAN OCEAN can see summarized in Figure 15.2. St. Helena Cocos D Over time, off- SOUTH Islands Natural selection is a mechanism Tahiti AMERICA spring with certain Rio de Janeiro Mauritius AUSTRALIA Visual Learning Sydney for change in populations. It occurs variations make Valparaiso Montevideo King when organisms with certain varia- up most of the Figure 15.1 Have the students PACIFIC George population and OCEAN Sound Hobart New tions survive, reproduce, and pass examine the photos of the finch, Falkland Islands Zealand may look entirely Cape Horn their variations to the next generation. tortoise, and iguana. Discuss each different from P Organisms without these variations their ancestors. organism, asking students to are less likely to survive and repro- identify its adaptations. C Galapagos marine iguanas duce. As a result, each generation con- eat algae on the ocean’s sists largely of offspring from parents bottom, an unusual food with these variations that aid survival. LS ResourceResource source for reptiles. Large claws Manager help them cling to slippery rocks. Manager 402 15.1 NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION 403 Section Focus Transparency 37 and Master L1 ELL PortfolioPortfolio MEETING INDIVIDUAL NEEDS Laboratory Manual, pp. 103-104 L2 Change over Time English Language Learners P Linguistic Have students make a Linguistic Review the meanings of collage showing how television, the words fit, fitter, and fittest. Help music, food, clothing, and movies have students form sentences using the three changed over time. Then, ask them to words. Then have them rearrange the LS describe changes in nature, such as words the, selects, nature, and fittest to P weather and tide. Help them compare form a sentence that summarizes Darwin’s P P these types of changes to those in organ- concept of natural selection. L1 ELL 402 isms over time. L1 P ELL 403

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LS LS Different Viewpoints Enrichment Darwin was not the only one to the problems is that evolutionary Have you noticed that some animals these modern mole-rat adaptations in Biology recognize the significance of natural processes are difficult for humans to have distinctive coloring but others might have evolved over millions of Using Figure 15.3 as a model, Provide students with a set of selection for populations. As a result observe directly. The short scale of don’t? Have you ever wondered how years from characteristics of their have the students illustrate or class data, such as the data they of his studies on islands near human life spans makes it difficult to such variations arose? Recall that an ancestors. describe possible evolutionary gathered in this chapter’s Getting Indonesia in the Pacific Ocean, comprehend evolutionary processes adaptation is any variation that aids The structural adaptations of com- sequences of one of the follow- Started. Ask different students to Alfred Russell Wallace, another that occur over millions of years. For an organism’s chances of survival in mon mole-rats include large teeth ing: (1) the evolution of long interpret the data to show how British naturalist, had reached a simi- some people the theory of evolution its environment. Thorns are an adap- and claws. These are body parts that necks in giraffes from short- the same information can be lar conclusion. After Wallace wrote is contradictory to their faith, and tation of some plants and distinctive help mole-rats survive in their envi- necked ancestors, (2) the evolu- interpreted differently. L2 Darwin to share his ideas about nat- they offer other interpretations of the colorings are an adaptation of some ronment by, for example, enabling tion of whales from terrestrial ural selection, Darwin and Wallace data. Many biologists, however, have animals. Darwin’s theory of evolution them to dig better tunnels. Structural carnivores, (3) the evolution of had their similar ideas jointly pre- suggested that the amount of scien- explains how adaptations may develop adaptations such as the teeth and Visual Learning flight in birds from bipedal sented to the scientific community. tific evidence supporting the theory in species. claws of mole-rats are often used to dinosaurs, (4) the evolution of Figure 15.3 illustrates the proba- However, it was Darwin who pub- of evolution is overwhelming. Almost defend against predators. Some adap- high-speed running in cheetahs ble evolution of the common lished the first book about evolution all of today’s biologists accept the the- Structural adaptations tations of other organisms that keep from slower movements of their mole-rat from a member of the called On the Origin of Species by ory of evolution by natural selection. arise over time predators from approaching include a ancestors. rodent family Bathyergidae. After Natural Selection in 1859. The ideas However, biologists are also now According to Darwin’s theory, rose’s thorns or a porcupine’s quills. P students have studied each step of detailed in Darwin’s book are today a more aware of genetics. Evolution is adaptations in species develop over Some other structural adaptations the illustration, ask them to list basic unifying theme of biology. more commonly defined by modern many generations. Learning about are subtle. Mimicry is a structural the steps that may have occurred biologists as any change in the gene adaptations in mole-rats can help adaptation that enables one species to Interpreting evidence pool of a population. you understand how natural selec- resemble another species. In one during the evolution of the sight- after Darwin less, cave-dwelling fishLS genus tion has affected them. Mole-rats form of mimicry, a harmless species Volumes of scientific data have that live underground in darkness are has adaptations that result in a physi- VIDEOTAPE Amblyopsis, and the blind, bur- Adaptations: Evidence Figure 15.3 been gathered as evidence for evolu- blind. These blind mole-rats have cal resemblance to a harmful species. The Secret of Life rowing snake genus Typhlops. for Evolution Darwin’s ideas about tion since Darwin’s time. Much of many adaptations that enable them Predators that avoid the harmful natural selection can It’s in the Genes: Evolution this evidence is subject to interpreta- Have you noticed that some plants to live successfully underground. species also avoid the similar-looking, explain some adapta- tion by different scientists. One of have thorns and some plants don’t? Look at Figure 15.3 to see how harmless species. See if you can tell tions of mole-rats. ResourceResource A The ancestors of today’s B Some ancestral rats may have C Ancestral rats that survived passed their D Over time, natural selection produced CD-ROM common mole-rats prob- avoided predators better than variations to offspring. After many modern mole-rats. Their blindness may ManagerManager Biology: The Dynamics ably resembled African others because of variations such generations, most of the population’s have evolved because vision had no of Life rock rats. as the size of teeth and claws. individuals would have these adaptations. survival advantage for them. Concept Mapping, p. 15 L3 Video: The Galapagos Disc 2 ELL Video: Adapted for Survival Laboratory Manual, Disc 2 pp. 105-108 L2 P P

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404 THE THEORY OF EVOLUTION 15.1 NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION 405

IOLOGYIOLOGY OURNAL PROJECT B J Internet Address Book Variation in Beans short, long, wide, thin, etc. Have them write Evidence for Natural Selection Note Internet addresses Logical-Mathematical Students can hypotheses that predict how each category Linguistic Have students describe that you find useful in study the effects of individual varia- of bean seed will grow. Then plant 3 or 4 the main evidence Darwin used in the space below for quick reference. tions by planting a pinto bean garden. Have beans from each category. Students should formulating his concept of natural selec- them wash their hands after handling bean observe the plants each day, recording their tion. Next, have them select an organism seeds. Obtain some pinto bean seeds and ask observations. Have them write a brief sum- and, in their own words, use the main the students to measure and observe them, P ideas of the concept of natural selection mary after 4-5 weeks of plant growth. L1 P placing the seeds into categories, such as ELL to explain the evolution of the organism. 404 L3 405 LS P LS

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LS LS MiniLab 15-1 Physiological adaptations can P the difference between a harmless fly Problem Solving Lab 15-1 MiniLab 15-1 Formulating Models and the wasp it mimics when you develop rapidly Problem-Solving Lab 15-1 Interpreting Data P Purpose look at Figure 15.4. In general, most structural adapta- In another form of mimicry, two or Purpose Students will model how a cam- Camouflage Provides an Adaptive Advantage tions develop over millions of years. How can natural selection be ouflage adaptationLS can aid an Camouflage is a structural adaptation that allows organisms more harmful species resemble each However, there are some adaptations observed? In some organisms that Students will analyze data from a organism’s survival. to blend with their surroundings. In this activity, you’ll dis- other. For example, yellow jacket hor- that evolve much more rapidly. For have a short life cycle, biologists have natural selectionLS study. cover how natural selection can result in camouflage adapta- nets, honeybees, and many other example, do you know that some of observed the evolution of adaptations Process Skills to rapid environmental changes. In the tions in organisms. species of wasps all have harmful the medicines developed during the Process Skills observe and infer, form a hypoth- stings and similar coloration and early 1950s, English biologist H. B. Procedure twentieth century to fight bacterial Kettlewell studied camouflage adapta- use a table, form a hypothesis esis behavior. Predators may learn ! Working with a partner, punch 100 diseases are no longer effective? tions in a population of light- and dark- quickly to avoid any organism Background Teaching Strategies dots from a sheet of white paper with When the antibiotic drug penicillin colored peppered moths, Biston betularia. a paper hole punch. Repeat with a with their general appearance. Biston betularia Have students do this activity was discovered about 50 years ago, it The moths rested on the trunks of trees A dark variety of peppered moth sheet of black paper. These dots will Another subtle adaptation was called a wonder drug because it that grew in both the country and the city. was first observed in English after studying camouflage. represent black and white insects. Moths are usually speckled gray-brown, and dark moths, which is camouflage (KAM uh flahj), killed many types of disease-causing cities in 1848. It was hard to see Explain that students will sim- @ Scatter both white and black dots on a an adaptation that enables occur occasionally, are black. Birds pluck the moths from the bacteria and saved many lives. Today, trees for food. Urban industrial pollution had blackened the on the dark tree trunks near pol- ulate how natural selection might sheet of black paper. species to blend with their surround- penicillin no longer affects as many bark of city trees with soot. In the photo, you see a city tree luted areas. Over the next 100 operate on a population of insects # Decide whether you or your partner will role-play a bird. ings, as shown in Figure 15.4. $ The “bird” looks away from the paper, then turns back, species of bacteria because some with dark bark similar to the color of one of the moths. years, near the cities, scientists that vary in color. Because well-camouflaged organisms species have evolved physiological and immediately picks up the first dot he or she sees. Analysis observed greater numbers of dark are not easily found by predators, (fihz ee uh LAHJ ih kul) adaptations to Expected Results % Repeat step 4 for one minute. Kettlewell raised more than 3000 caterpillars to provide moths relative to light moths. In they survive to reproduce. Try the prevent being killed by penicillin. Most groups will have picked up adult moths. He marked the wings of the moths these cater- the 1950s, English scientist H. B. Analysis MiniLab to experience how camou- Look at Figure 15.5 to see how more white dots than black dots. pillars produced so he would recapture only his moths. In a Kettlewell tested the hypothesis 1. What color dots were most often collected? flage can help an organism survive. resistance develops in bacteria. series of trials in the country and the city, he released and Analysis 2. How does color affect the survival rate of insects? Then use the Problem-Solving Lab on Physiological adaptations are recaptured the moths. The number of moths recaptured in a that natural selection accounted 1. white dots 3. What might happen over many generations to a similar the next page to analyze data from an changes in an organism’s metabolic trial indicates how well the moths survived in the environ- for the difference. population in nature? ment. Examine the table below. 2. English study of camouflaged pep- processes. In addition to species of Light-colored insects may be Teaching Strategies pered moths. bacteria, scientists have observed seen and preyed on more Table 15.1 Comparison of country and city moths these adaptations in species of insects Remind students that these easily than dark-colored Numbers of Numbers of insects. Therefore, dark- and weeds that are pests. After years Location light moths dark moths data are from an experiment used Figure 15.4 of exposure to specific pesticides, to support the theory of evolu- colored insects have a higher Mimicry and camouflage are protective adaptations of organ- Country Released 496 488 many species of insects and weeds tion by natural selection. survival rate. isms. The colors and body shape of a yellow jacket wasp (a) Recaptured 62 34 and a harmless syrphid fly (b) are similar. Predators avoid have become resistant to these chem- 3. Over time, an insect popula- City Released 137 493 Thinking Critically tion might become dark- both insects. Camouflage enables organisms, such as this icals that used to kill them. leaf frog (c), to blend with their surroundings. Recaptured 18 136 country/light moths = 12.5%; colored because light-colored country/dark moths = 0.7%; insects were eliminated from c Thinking Critically a city/light moths = 13.0%; the population. Figure 15.5 Calculate the percentage of moths recaptured in each The development of bacterial experiment and explain any differences in survival rates in the city/dark moths = 27.6% resistance to antibiotics is country and the city moths in terms of natural selection. The differences in survival rates Assessment direct evidence for evolution. are due to camouflage. There was natural selection for the dark Knowledge Have students Antibiotic variation in the city where pollu- research and write a summary Non-resistant bacterium tion killed the lichen on trees, about insect adaptations that and natural selection for the light aid survival in specific environ- variation in the country where ments. Use the Performance Task Resistant lichens were present. Assessment List for Writing in bacterium Science in PASC, p. 87. L2 b Assessment ResourceResource A The bacteria in a population B When the population is C The resistant bacteria live Knowledge Have students ManagerManager vary in their ability to resist exposed to an antibiotic, only and produce more resistant predict the effect on a peppered 406 antibiotics. the resistant bacteria survive. bacteria. moth population if reddish-green BioLab and MiniLab Work- lichens invaded a forest. Use the sheets, p. 71 L1 P PortfolioPortfolio PortfolioPortfolio Performance Task Assessment List for Formulating a Hypothe- Camouflage and Mimicry Breeds of Dogs sis in PASC, p. 21. L1 Linguistic Have the students write VIDEODISC Linguistic Have students prepare a LS about an organism that has camou- The Secret of Life short report about a dog breed of flage or mimicry adaptations. The report Camouflage: Caterpillars their choice, describing its characteristics, should include the organism’s name, de- the reasons why it was originally bred, tails about its environment and predators, !<:PWN8B" the details about its breeding, and the P P and a description of its camouflage or Camouflage: Spider characteristics of closely related breeds. P mimicry adaptations. L3 P Students should include a picture of the 406 !<;DWY~I" breed in their report. L1 P 407 LS LS LS LS P LS

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LS Display Assessment Other Evidence the same with fossils. Although pale- Figure 15.7 ontologists do not have intermediate The forelimbs Obtain samples of different bird Performance Assessment for Evolution forms of most species, they can often of crocodiles, wings (turkey, chicken, duck, or whales, and birds in the Biology Classroom, p. 35, The development of physiological still understand the overall picture of guinea hen) from a supermarket. Model for Sexual Reproduction. are homologous resistance in species of bacteria, how a species evolved. structures. The Display the wings and have stu- Have students do this activity to insects, and plants is direct evidence Fossils are found throughout the bones of each dents identify the homologous reinforce the idea that natural of evolution. However, most of the world. As the fossil record becomes are modified for structures. Discuss the structure selection occurs if some individu- evidence for evolution is indirect, more complete, the sequences of their function. and function of a bird’s wing. Ask als inherit certain traits that equip coming from sources such as fossils evolution become more clear. For students if their observations sup- them to cope better with the and studies of anatomy, embryology, example, in Figure 15.6 you can see port the idea that the organisms environment. L1 ELL and biochemistry. how paleontologists sequenced the are closely related. possible forms that led to today’s Visual Learning Fossils camel after piecing together fossil Crocodile Fossils are an important source of skulls, teeth, and limb bones. forelimb Tying to Previous Use Figure 15.6 Pto illustrate evolutionary evidence because they Knowledge that, although the fossil record provide a record of early life and evo- Anatomy Point out that the theory of evo- provides evidence for evolution, Bird wing lutionary history. For example, pale- Structural features with a common lution predicts that organisms a relatively complete sequence of Whale ontologists conclude from fossils that evolutionary origin are called with similar physical characteris- fossils, such as those that exist for forelimb LS the ancestors of whales were proba- homologous structures. Homolo- tics will also have similar DNA. camels and horses, is rare. Relate P bly land-dwelling, doglike animals. gous structures can be similar in Briefly review the structure and this fact to students’ previous Although the fossil record provides arrangement, in function, or in both. function of DNA. Remind stu- knowledge of problems in fossil evidence that evolution occurred, the For example, look at the forelimb bones dents that DNA makes up the preservation, dating, and inter- record is incomplete. Working with of the animals shown in Figure 15.7. from a common ancestor. It would be genes of an organism that are part pretation. Figure 15.6 an incomplete fossil record is some- Although the bones of each forelimb unlikely for so many animals to have LS of the organism’s chromosomes. Paleontologists have thing like trying to put together a jig- are modified for their function, the similar structures if each species used fossils to trace saw puzzle with missing pieces. But, basic arrangement of the bones in arose separately. the evolution of the Figure 15.8 modern camel. About after the puzzle is together, even with each limb is similar. Evolutionary The structural or functional simi- Insect and bird wings 66 million years ago missing pieces, you will probably still biologists view homologous structures larity of a body feature doesn’t always are similar in function the ancestors of understand the overall picture. It’s as evidence that organisms evolved mean that two species are closely but not in structure. camels were as small CD-ROM related. In Figure 15.8, you can Bones are the frame- as rabbits. work of bird wings, VIDEODISC Biology: The Dynamics compare the wing of a butterfly with the wing of a bird. Bird and butterfly whereas a tough The Infinite Voyage: of Life material called chitin wings are not similar in structure, but The Great Dinosaur Explorations: The Record of Life composes insect they are similar in function. The Hunt: Where the Great Hunt Disc 2 wings. wings of birds and insects evolved Began (Ch. 1), 4 min. VIDEODISC independently of each other in two The Secret of Life distantly related groups of ancestors. !7-8J" Horse Evolution The body parts of organisms that do The Great American Bone Rush not have a common evolutionary ori- (Ch. 3), 2 min. !7;B~F" gin but are similar in function are called analogous structures. The Infinite Voyage The Great Although analogous structures !7ALD" Dinosaur Hunt, New Dinosaur don’t shed light on evolutionary rela- Discoveries and Their Link with tionships, they do provide evidence Today (Ch. 10) of evolution. For example, insect and !8$.J" 8 min. bird wings probably evolved sepa- rately when their different ancestors Paleocene Eocene Oligocene Miocene 66 millions of 54 millions of 37 millions of 26 millions of Present adapted independently to similar years ago years ago years ago years ago ways of life.

15.1 NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION 409

PROJECT MEETING INDIVIDUAL NEEDS Learning Disabled Evolving Bacteria Students should identify the bacterium, the sil sequence of one of these organisms, and Interpersonal Have student groups disease it causes, how it is transmitted, and Naturalist The fossil records of some point out the organism’s major characteristics organisms, such as camels, horses, ele- in each stage of the sequence. Have them research for a class presentation a bac- the data that suggest the bacterium is resis- P terium that has evolved quickly to develop tant to antibiotic treatment. Students can phants, and the extinct titanotheres, are rel- summarize the organism’s major changes resistance to antibiotics. Possible bacteria make visuals—graphs, data tables, and time atively complete and show evolutionary during its evolution. L1 ELL P include those that cause staph and strep in- lines—to illustrate their presentations. L2 change. Give students illustrations of the fos- fections, TB, and childhood ear infections. COOP LEARN LS P P 408 LS 409

LS LS P P

LS LS Visual Learning Figure 15.9 b Extension Figure 15.9 Ask students what Vestigial structures, such as Have students answer the prob- Eubacteria Archaea Eukaryota the function of the vestigial wings the forelimbs of the extinct lem: Anteaters, toothless mam- elephant bird (a) and those may have been. Flight in ancestral of the present-day ostrich mals that live in South American Animals Ciliates Fungi species (b), are evidence of Purple Methanogens Extreme rain forests, feed on termites. If bacteria Gram thermophiles evolution because they positive the termites they normally feed Different Viewpoints in show structural change bacteria on are replaced by termites that over time. Cyanobacteria Plants Biology Green are too large to swallow whole, non-sulfur how might the anteaters change The use of embryological evi- bacteria over time? dence to support the common Flavobacteria Extreme Flagellates ancestry of organisms has both halophiles a proponents and opponents. Some Sporozoans Assessment people interpret this kind of data Thermotoga to indicate that all organisms are Portfolio Ask the students related, and others do not. to research an organism and describe five of its adaptations. Then, have them select a new Ancestral prokaryotes environment for the organism and predict how natural selection 3 Assess Another type of body feature that ancestral birds probably became quite P would affect the organism there. suggests evolutionary relationship is a large and unable to fly, features evi- individuals and species. Comparisons and DNA nucleotide sequences to Figure 15.11 WORD Origin L2 P Check for Understanding vestigial structure (veh STIHJ ee ul)— dent in fossils of the elephant bird of the DNA or RNA of different construct evolutionary diagrams. The This evolutionary Linguistic Have students vestigial a body structure that has no function and present in the African ostrich. species produce biochemical evidence evolutionary diagram you see in diagram is based on From the Latin comparisons of describe how each of the in a present-day organism but was for evolution. Today, many scientists Figure 15.11 was constructed using LS word vestigium, probably useful to an ancestor. A Embryology organisms’ RNA and following concepts relates to nat- meaning “sign.” use the results of biochemical studies the results of biochemical analysis structure becomes vestigial when the It’s very easy to see the difference supported by other 4 Close ural selection: overproduction, The forelimbs to help determine the evolutionary and other data, including anatomical LS between an adult bird and an adult data. of ostriches are species no longer needs the feature. relationships of species. data. Notice that it divides all species favorable variations, population mammal, but can you distinguish Activity vestigial structures. Although the structure has no func- Since Darwin’s time, scientists into three domains: the Archaea, the change over time. L1 between them by looking at their tion, it is still inherited as part of the have constructed evolutionary dia- Eubacteria, and the Eukaryota—an P Interpersonal Divide the embryos? An embryo is the earliest body plan for the species. grams that show levels of relation- idea that underlies one of the most class into groups and show Reteach stage of growth and development of Many organisms have structures ships among species. In the 1970s, recently developed classification sys- photos of different organisms. both plants and animals. The embryos Intrapersonal Have students Figure 15.10 with no apparent function. The eyes some biologists began to use RNA tems for organisms. Have groups brainstorm a list identify five of an organism’s Comparing embryos of blind mole-rats and cave fish are of a fish, a reptile, a bird, and a mam- of the organisms’ adaptations mal are shown in Figure 15.10. You LS traits, such as its hair color or size. can reveal their evo- vestigial structures because they have and three explanations for each lutionary relation- no function. In Figure 15.9, you see can see a tail and gill slits in all the Ask them to name five variations adaptation. L1 COOP LEARN for each trait and state how each ships. The presence two flightless birds—an extinct ele- embryos. You know that reptiles, Section Assessment of gill slits and tails phant bird and an African ostrich— birds, and mammals do not have gills variation would affect the organ- in early vertebrate Understanding Main Ideas strains of the parasite have appeared that are P P with extremely reduced forelimbs. when they are mature. As develop- ism in its environment. L1 embryos shows that 1. Briefly explain Darwin’s ideas about natural resistant to the drugs used to treat the disease. ResourceResource they may share a Their ancestors probably foraged on ment continues, the differences in the selection. Explain how this could be an example of natural ManagerManager common ancestor. land for food and nested on the embryos will increase until you can 2. Some snakes have vestigial legs. Why is this con- selection occurring. ground. As a result, over time, the distinguish among them. However, sidered evidence for evolution? SKILL REVIEWEVIEW Reinforcement and Study the similarities among the young 3. Explain how mimicry and camouflage help LS LS Guide, pp. 65-66 L2 embryos suggest evolution from a dis- species survive. 6. Sequencing Fossils indicate that whales evolved 4. How do homologous structures provide evidence from ancestors that had legs. Using your knowl- Content Mastery, p. 74 L1 tant, common ancestor. for evolution? edge of natural selection, sequence the steps VIDEODISC Gill slits Gill slits P that may have occurred during the evolution of The Infinite Voyage Biochemistry Tail Tail Thinking Critically whales from their terrestrial, doglike ancestors. The Great Dinosaur Biochemistry also provides evi- 5. A parasite that lives in red blood cells causes the For more help, refer to Organizing Information Hunt, Newborns: ExaminingP dence for evolution. It reveals infor- disease called malaria. In recent years, new in the Skill Handbook. Dinosaur Eggs (Ch. 7) Fish Reptile Bird Mammal mation about relationships between LS 8 min. 30 sec. P 410 THE THEORY OF EVOLUTION 15.1 NATURAL SELECTION AND THE EVIDENCE FOR EVOLUTION 411 LS !7itB" P PortfolioPortfolio LS Section Assessment Evolution embryos have gill slits during their early 1. Organisms produce many offspring 3. They reduce a species’ visibility to 6. Ancestral whales were forced to live Logical-Mathematical Have students developmental stages. with variations, some of which enable predators or mimic the appearance of in water. Individuals with variationsLS describe how each statement that fol- About 20% of human DNA is identical to longer survival than others. Variations an organism that predators avoid. that had survival advantages in water lows supports the theory of evolution. mouse DNA, and 98% of human DNA is with a survival advantage are wide- 4. They suggest common ancestry. reproduced, passing on these varia- An insecticide does not kill an aphid identical to chimpanzee DNA. P spread among descendants. 5. Some parasites had a variation that tions. Over time the variations species. The fossil record shows that camels were 2. They suggest that snake ancestors made them resistant to drugs. They became common in the population. The feet of geckos enable them to climb once the size of rabbits. L3 P had functional legs and today’s survived and passed this variation to vertically on trees and rocks. snakes may have evolved from them. their offspring. 410 Human, rabbit, chicken, and lizard LS 411 LS P

LS SECTION PREVIEW Section 15.2 First generation Phenotype Allele 2 Teach Objectives Section frequency frequency Summarize the effects Visual Learning of the different types White = 0 R = 0.75 of natural selection on 15.2 Mechanisms of Kinesthetic Figure 15.12 Prepare gene pools. Pink = 0.5 R' = 0.25 Students can use beans to Relate changes in Evolution Red = 0.5 model allelic frequency. Mix red Key Concepts genetic equilibrium to mechanisms of RR RR RR' RR' RR RR' RR RR' pinto beans, black beans, and Students will learn about gene speciation. ou may recognize the birds white navy beans in a large con- pools and how natural selection Explain the role of natural selection shown here as meadowlarks. tainer. Have students withdraw affects them. Then they will These birds range throughout Second generation Phenotype Allele 20 random beans to represent the in convergent and Y frequency frequency study factors that may contribute divergent evolution. much of the United States. Meadowlarks gene pool of a population with to speciation. Finally, specific Vocabulary look so similar that it’s often difficult to White = 0.125 R = 0.75 the genotypes BB (black bean), examples of different patterns of gene pool tell them apart. But if you listen, you’ll Pink = 0.25 R' = 0.25 BB* (white bean), and B*B* (red evolution will enhance the stu- allelic frequency hear a melodious bubbling sound from the genetic equilibrium Red = 0.625 bean). Have them calculate the dents’ understanding of the the- genetic drift Western meadowlark, whereas the phenotype frequencies by divid- stabilizing selection ory of evolution. Eastern meadowlark produces a clear RR RR' RR RR' RR R'R' RR RR directional selection ing the number of each pheno- disruptive selection whistle. Although they are closely related type by 20, and the allelic Planning speciation and occupy the same ranges in parts of frequencies by counting the geographic isolation P Purchase beans for the Visual reproductive isolation the central United States, these different genes that characterize the traits of Look at the population of snap- Figure 15.12 numbers of each allele and divid- Learning and BioLab, un- polyploid meadowlarks do not normally interbreed the species, and these genes exist dragons shown in Figure 15.12. A Incomplete domi- ing by 40. L1 ELL gradualism shelled peanuts for MiniLab and are classified as distinct species. Western Eastern as pairs of alleles. Just as all of the pattern of heredity called incomplete nance produces punctuated equilibrium meadowlark— meadowlark— three phenotypes: adaptive radiation 15-2, and carnations for the Sturnella neglecta Sturnella magna individuals make up the population, dominance, which you learned about red flowers (RR), The BioLab at the divergent evolution all of the genes of the population’s earlier, governs flower color in snap- ILSNTERNET Tech Prep. convergent evolution white flowers (R'R'), end of the chapterP I Gather equipment for the individuals make up the population’s dragons. If you know the flower-color and pink flowers can be used at this Alternative Lab. genes. Evolution occurs as a popula- genotypes of the snapdragons in a (RR'). Although point in the lesson. tion’s genes and their frequencies population, you can calculate the the phenotype Populations, not individuals, change over time. allelic frequency for the flower-color frequencies of Population Genetics the generations evolve How can a population’s genes alleles. The population of snapdrag- LS and Evolution vary, the allelic Quick Demo 1 Focus Can individuals evolve? That is, change over time? Picture all of the ons is in genetic equilibrium when frequencies for the P When Charles Darwin developed can an organism respond to natural alleles of the population’s genes as the frequency of its alleles for flower R and R' alleles do Bellringer his theory of natural selection in the selection by acquiring or losing char- being together in a large pool called a color is the same in all its generations. not vary. Use a world map and explain 1800s, he did so without knowing acteristics? Recall that genes deter- gene pool. The percentage of any that many human populations Before presenting the lesson, about genes. Since Darwin’s time, mine most of an individual’s features, specific allele in the gene pool is called Changes in genetic equilibrium are isolatedLS for geographical, display Section Focus Trans- scientists have learned a great deal such as tooth shape or flower color. If the allelic frequency. Scientists A population that is in genetic political, or other reasons. Ask parency 38 on the overhead pro- about genes and modified Darwin’s an organism has a feature—a varia- calculate the allelic frequency of an equilibrium is not evolving. Because students how this might affect jector and have students answer ideas accordingly. At first, genetic tion called a phenotype in genetic allele in the same way that a baseball allelic frequencies remain the same, these nations’ gene pools. the accompanying questions. information was used to explain the terms—that is poorly adapted to its player calculates a batting average. phenotypes remain the same, too. L1 ELL variation among individuals of a pop- environment, the organism may be They refer to a population in which Any factor that affects the genes in ulation. Then, studies of the complex unable to survive and reproduce. the frequency of alleles remains the the gene pool can change allelic fre- behavior of genes in populations of However, within its lifetime, it can- same over generations as being in quencies, disrupting a population’s plants and animals developed into the not evolve a new phenotype in genetic equilibrium. In the Math genetic equilibrium, which results in Evolving TransparencyP 38 SECTION FOCUS Populations Use with Chapter 15, field of study called population response to its environment. Connection at the end of the chapter, the process of evolution. Section 15.2 genetics. The principles of today’s Rather, natural selection acts on you can read about the mathematical You have learned that one mecha- modern theory of evolution are the range of phenotypes in a popula- description of genetic equilibrium. nism for genetic change is mutation. VIDEOTAPE rooted in population genetics and tion. Recall that a population consists You can study the effect of natural Environmental factors, such as radia- The Secret of Life LS other related fields of study and are of all the members of a species that selection on allelic frequencies in the tion or chemicals, cause many muta- Gone Before You Know It: The P expressed in genetic terms. live in an area. Each member has the BioLab at the end of the chapter. tions, but other mutations occur by Biodiversity Crisis Stream A CD-ROM 412 THE THEORY OF EVOLUTION 15.2 MECHANISMS OF EVOLUTION 413 Biology: The Dynamics of Life LS Exploration: Selection Pressure Stream B BIOLOGYIOLOGY JOURNAL Resource Manager Disc 2 1 Stream A and Stream B are located on two isolated islands with Desert Adaptions similar characteristics. How do these two stream beds differ? Genetic Drift 2 Suppose a fish that varies in color from a lighter shade to a

Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc. darker shade is introduced from Stream A into Stream B. How Linguistic Ask students to imagine might the color of the fish population in Stream B change Section Focus Transparency 38 and Logical-Mathematical Have Linguistic Have students write a short over time? P Master L1 ELL students use a bouquet of changes in food, clothing, shelter, and summary of how genetic drift may BIOLOGY: The Dynamics of Life SECTION FOCUS TRANSPARENCIES carnations (red, pink, and white) other factors that would be useful if their affect small populations. L3 environment suddenly became desertlike. to calculate the frequency of alleles that P determine flower color. Students should Have them write a short story about life in P P LS prepare a chart similar to the one in the new environment. L1 Figure 15.12. L2 412 LS P 413 LS LS P LS

P LS P

LS LS Concept Development original ancestors represent only a When individuals enter a population, MiniLab 15-2 Point out that in small popula- P Figure 15.13 small fraction of the gene pool of the their genes are added to the pool. MiniLab 15-2 Collecting Data tions that interbreed, such as cer- Genetic drift can entire species and are the only genes Mutation, genetic drift, and gene Purpose tain religious groups and royal result in an increase available to pass on to offspring. The flow may significantly affect the evo- Students will measure and deter- of rare alleles in a Detecting a Variation Pick almost any families, gene pools change distinctive forms of life that Darwin lution of small and isolated gene trait—height, eye color, leaf width, or mine that peanut shells vary in quickly because the number of small population found in the Galapagos Islands may pools, such as those on islands. LS such as in the Amish seed size—and you can observe how length. potential mates is limited. have resulted from genetic drift. However, their effect is often the trait varies in a population. Some community of Process Skills Lancaster County, Genetic drift has been observed in insignificant in larger, less isolated variations are an advantage to an Tying to Previous Pennsylvania. some small human populations that gene pools. Natural selection is usu- organism and some are not. collect data, interpret data, make and use tables, make and use Knowledge have become isolated due to reasons ally the most significant factor that Procedure such as religious practices and belief causes changes in established gene ! Copy the data table shown here, but include graphs, measure in SI Review meiosis. Explain how systems. For example, in Lancaster pools—small or large. the lengths in millimeters (numbers 25 through 45) random factors involved in some Teaching Strategies County, Pennsylvania, there is an that are missing from this table. of the steps of meiosis can con- Amish population of about 12 000 Natural selection acts Have students wash their tribute to genetic drift. people who have a unique lifestyle on variations Data Table hands after handling peanuts. and marry other members of their As you’ve learned, traits have vari- Length in mm 20 21 22 23 24 — 46 47 48 49 50 Unshelled peanuts are avail- Using An Analogy community. By chance, at least one ation, as shown in the butterflies pic- Checks able in most large supermarkets. of the original 30 Amish settlers in tured in Figure 15.14. If you mea- Have students pool their data Flip a coin to show how small My Data— chance. Of the mutations that affect this community carried a recessive sured the thumb lengths of everyone Number of shells on the chalkboard. populations can be affected by organisms, many are lethal, and the allele that results in short arms and in your class, you’d find average, Class Data— Tell students that peanut shells genetic drift. If you flip a coin organisms do not survive. Thus, legs and extra fingers and toes in off- long, and short thumbs. Try measur- Number of shells contain seeds, and discuss briefly 100 times, the chances of getting lethal mutations are quickly elimi- spring, Figure 15.13. Because of the ing the variations in peanut shells in the role of seeds in plant repro- 100 heads and 0 tails—or even 80 nated. However, occasionally, a small gene pool, many individuals the MiniLab on this page. @ Use a millimeter ruler to measure a peanut shell’s length. duction. heads and 20 tails—is unlikely. mutation results in a useful variation, inherited the recessive allele over Recall that some variations In the Checks row, check the length you measured. The result will probably be close and the new gene becomes part of time. Today, the frequency of this increase or decrease an organism’s # Repeat step 2 for 29 more shells. Expected Results to 50-50. But if you flip the coin the population’s gene pool by the allele among the Amish is high—1 in chance of survival in an environment. $ Count the checks under each length and enter the total in Student data should indicate a the row marked My Data. 10 times, the chance of getting 8 process of natural selection. 14 rather than 1 in 1000 in the larger These variations can be inherited and wide range in shell length. There % Use class totals to complete the row marked Class Data. heads and 2 tails—or even 10 Another mechanism that disrupts a population of the United States. are controlled by alleles. Thus, the should be few shells at either heads and 0 tails—is likely to population’s genetic equilibrium is Genetic equilibrium is also dis- allelic frequencies in a population’s Analysis extreme and the majority of occur. Similarly, the loss of alleles genetic drift—the alteration of rupted by the movement of individu- gene pool will change over genera- 1. Was there variation among the lengths of peanut shells? shells should fall in the middle by chance is lower in large popu- allelic frequencies by chance events. als in and out of a population. The tions due to the natural selection of Use specific class totals to support your answer. range of the measurements. lations than in small ones. Genetic drift can greatly affect small transport of genes by migrating indi- variations. There are three different 2. If larger peanut shells were a selective advantage, would populations that include the descen- viduals is called gene flow. When an types of natural selection that act this be stabilizing, directional, or disruptive selection? Analysis dants of a small number of organ- individual leaves a population, its on variation: stabilizing, directional, Explain your answer. 1. yes—student answers will ResourceResource isms. This is because the genes of the genes are lost from the gene pool. and disruptive. vary Manager 2. Directional selection—larger Manager shells may favor the survival Basic Concepts Transparency of offspring because they may 21 and Master L2 ELL contain larger, more viable BioLab and MiniLab Work- Figure 15.14 seeds. These swallowtail sheets, p. 72 L2 butterflies live in P different areas of North America. Assessment Despite their slight Portfolio Have students variations, they prepare a histogram of the class can interbreed to P LS produce fertile data. Use the Performance Task offspring. Assessment List for Graph from P Papilio ajax ajax Papilio ajax ampliata Papilio ajax curvifascia Papilio ajax ehrmanni Data in PASC, p. 39. L1 P

LS 414 THE THEORY OF EVOLUTION 15.2 MECHANISMS OF EVOLUTION 415 LS LS Alternative Lab Materials 3. Pour streptomycin agar into dish A-B. stopper and flame the lip of the bacte- have inoculated and recovered them. Assessment culture of Bacillus subtilis, 3 tubes of nutri- Place the dish on a pencil, so the liquid rial culture. Observe them after 24 hours. Dispose Knowledge What is each dish’s ent agar, tube of streptomycin agar, inocu- flows to one side to solidify. CAUTION: 7. Dip the loop into the culture and of used petri dishes as your teacher Bacterial Resistance purpose? A-B is experimental; C-D is the P lation loop, 2 petri dishes, Bunsen burner, Liquid agar is hot. remove it. Flame the lip of the con- instructs. control. Explain your observations of the wax pencil, test tube 4. After the agar solidifies, pour a tube of tainer again and replace the stopper. P Purpose Expected Results dishes. Streptomycin accounts for the differ- hot nutrient agar into the dish and 8. Streak the agar in dish A-B with the Students will study variation in bacterial Procedure There should be more bacterial growth in ent number of colonies. Use the cover the dish after it solidifies. loop. Do not break the agar surface. resistance to antibiotics. Dispose of used Give the following directions. the C-D dish than in the A-B dish. Performance Task Assessment List for 5. Pour the other tubes of agar into the 9. Repeat steps 6-8 on the C-D dish. dishes afterLS autoclaving or incinerating. 1. Wear goggles, aprons, and disposable Analysis Assessing an Experiment in PASC, C-D dish. Cover the dish after it cools. 10. Recover the dishes, invert them, and LS gloves when working with bacteria. Have students sketch and describe the p. 33. 2. Write A and B on the halves of one 6. Sterilize the inoculation loop in the place them in a dark drawer or closet. appearance of both plates. 414 petri dish and C and D on another. Bunsen burner’s flame. Remove the Do not open the dishes again after you 415 Visual Learning Discussion Figure 15.15 Stabilizing selection is natural Natural selection can significantly Physical barriers can prevent Figure 15.15 illustrates the three Different types of natural selection act over the range of selection that favors average individ- alter the genetic equilibrium of a interbreeding Remind students that scientists main types of natural selection. a trait’s variation. The red, bell-shaped curve indicates a uals in a population as shown in population’s gene pool over time. used to classify organisms only trait’s variation in a population. The blue, bell-shaped In nature, physical barriers can Refer to each type and offer stu- curve indicates the effect of a natural selection. Figure 15.15. Consider a population Significant changes in the gene pool break large populations into smaller on the basis of morphological dents several other examples of of spiders in which average size is a can lead to the evolution of a new ones. Lava from volcanic eruptions comparisons. This type of classi- each. survival advantage. Predators in the species over time. can isolate populations. Sea-level fication is useful but limited. For area might easily see and capture spi- changes along continental shelves can example, using morphological Reinforcement Selection for Normal variation ders that are larger than average. create islands. The water that sur- classification, North American However, small spiders may find it The Evolution Logical-Mathematical Have average size rounds an island isolates its popula- yellow flickers, red-shafted flick- spiders difficult to find food. Therefore, of Species tions. Geographic isolation occurs WORD Origin ers, and their hybrid offspring students describe the type of in this environment, average-sized natural selection in each of the You’ve just read about how natural whenever a physical barrier divides speciation could be considered three differ- spiders are more likely to survive— processes such as mutation, genetic a population. From the Latin ent species. following examples. they have a selective advantage, or word species, drift, gene flow, and natural selection A new species can evolve when a According to the biological Members of a population of are “selected for.” meaning “kind.” can change a population’s gene pool population has been geographically species concept, organisms are Amazon tree frogs hop from Directional selection occurs Speciation is a over time. But how do the changes in isolated. For example, imagine a pop- process that pro- classified by whether or not they tree to tree searching for food when natural selection favors one of the makeup of a gene pool result in the ulation of tree frogs living in a rain duces two species in the rain forest. They vary in the extreme variations of a trait. For can naturally interbreed with one A Stabilizing selection favors average individuals. This type evolution of new species? Recall that a forest, Figure 15.16. If small popula- from one. leg length. Events result in example, imagine a population of another to produce fertile off- of selection reduces variation in a population. species is defined as a group of organ- tions of tree frogs were geographi- spring, as the yellow flickers and massive destruction of the for- woodpeckers pecking holes in trees isms that look alike and can inter- cally isolated, they would no longer red-shafted flickers can do. Elicit est’s trees. After several gener- to feed on the insects living under breed to produce fertile offspring in be able to interbreed and exchange ations, only long-legged tree Selection the bark. Suppose that a species of nature. The evolution of new species, genes. Over time, each small popula- from students how many species Normal for longer insect that lives deep in tree tissues of North American flickers exist frogs remain alive. directional variation beaks a process called speciation (spee shee tion might adapt to its environment selection invades the trees in a woodpecker AY shun), occurs when members of through natural selection and develop based on this biological species Different grass plants in a pop- population’s territory. Only wood- similar populations no longer inter- its own gene pool. Eventually, the definition. one ulation range in length from peckers with long beaks could feed breed to produce fertile offspring gene pools of each population might on that insect. Therefore, the long- 8 cm to 28 cm. The 8-10 cm within their natural environment. become so different that new species beaked woodpeckers in the popula- grass blades receive little sun- tion would have a selective advantage Figure 15.16 light, and the 25-28 cm grass over woodpeckers with very short or When geographic isolation blades are eaten quickly by average-sized beaks. divides a population of tree frogs, the individuals no longer VIDEODISC grazing animals. stabilizing Finally, in disruptive selection, mate across populations. Biology: The Dynamics selection B Directional selection favors one of the extreme variations individuals with either extreme of a of Life The spines of a sea urchin of a trait and can lead to the rapid evolution of a population. trait’s variation are selected for. Geographic Isolation (Ch. 6) population’s members vary in Consider, for example, a population Disc 1, Side 2, 17 sec. length. The short-spined sea Selection for Normal Selection for of marine organisms called limpets. urchins are camouflaged easily light limpets variation dark limpets The shell color of limpets ranges on the seafloor. However, from white, to tan, to dark brown. As !7hÑ" long-spined sea urchins are adults, limpets live attached to rocks. well defended against preda- On light-colored rocks, white-shelled tors. disruptive selection limpets have an advantage because Have students illustrate each sit- their bird predators cannot easily see uation and predict what will hap- them. On dark-colored rocks, dark- pen to the members of each colored limpets have the advantage population if natural selection because they are camouflaged. On the other hand, birds easily see tan- CD-ROM continues to operate. L1 C Disruptive selection favors both extreme variations of a colored limpets on either the light or View an animation trait, resulting eventually in no intermediate forms of the trait dark backgrounds. Disruptive selec- of Figure 15.16 in the Presentation Builder of and leading to the evolution of two new species. tion tends to eliminate the interme- ResourceResource the Interactive CD-ROM. ManagerManager diate phenotypes. Basic Concepts Transparency 416 THE THEORY OF EVOLUTION 15.2 MECHANISMS OF EVOLUTION 417 22 and Master L2 ELL Critical Thinking/Problem BIOLOGYIOLOGY JOURNAL Solving L3 P Internet Address Book PROJECT Mammalian Evolution P Populations and Natural Note Internet addresses dae, Camelidae, Mustelidae, Felidae, and Selection that you find useful in Interpersonal Groups of students can Ursidae. Projects should contain details LS Linguistic Have students write and the space below for quick reference. prepare a written report, oral report, about the mammals, such as their structure illustrate a short story about the or poster project about the geographic and and behavior, a brief summary of their fossil P P P LS effects of natural selection on a specific reproductive isolation effect of plate tecton- record, and explanations for how they population. Have them predict what hap- ics on a mammalian family. Some families to evolved. L2 ELL COOP LEARN P pens to the population if all three types of research are: Bradypodidae, Myrmecophagi- P LS natural selection occur in it. L2 416 LS LS 417 P LS LS P LS P LS LS Concept Development Quick Demo Speciation can occur quickly that speciation occurs relatively or slowly quickly, in rapid bursts, with long Darwin believed that species Use hypothetical examples to Although polyploid speciation periods of genetic equilibrium in evolve slowly over long periods illustrate the concepts of geo- New takes only one generation, most between. According to this hypothe- of time. For example, fossils show graphic and reproductive iso- Abnormal polyploid other mechanisms of speciation do sis, environmental changes, such as that today’s horseshoe crabs, gametes (2n) species lation using the chalkboard or not occur as quickly. What is the higher temperatures or the introduc- genus Limulus, are nearly identi- overhead projector. Show a Fertilization usual rate of speciation? tion of a competitive species, lead to cal to ancestors that lived hun- Zygote Scientists once argued that evolu- rapid changes in a population’s gene dreds of millions of years ago. If population of organisms in an Nondisjunction (4n) environment. Then split the tion occurs at a slow, steady rate, with pool. Speciation happens quickly—in possible, show a modern speci- population as a result of an small, adaptive changes gradually about 10 000 years or less. Like grad- men of the horseshoe crab and a accumulating over time in popula- ualism, punctuated equilibrium is event such as the formation of fossil counterpart to demonstrate Sterile plant tions. Gradualism is the idea that supported by fossil evidence as shown a volcano or a canyon that re- their similarities. Remind stu- Fertilization species originate through a gradual in Figure 15.18. dents that scientists have found sults in two new environments Biologists generally agree that Parent plant change of adaptations. Some evi- Figure 15.18 limited support for the idea of for the populations. Students Normal Zygote dence from the fossil record supports both gradualism and punctuated (2n) Normal The fossil record of gradualism in the fossil record. in small groups can brainstorm Meiosis begins meiosis gametes (n) (3n) gradualism. For example, fossil evi- equilibrium can result in speciation, elephant evolution three changes they predict will supports the view of However, point out some exam- P dence shows that camels evolved depending on the circumstances. It occur in each subpopulation Figure 15.17 of tree frogs would evolve in the plants and some species of animals slowly and steadily over time. shouldn’t surprise you to see scien- punctuated equilib- ples that do support it. rium. Three elephant over time. Many flowering different forest patches or the popu- have evolved in the same geographic In 1971, Stephen J. Gould and tists offer alternative hypotheses to plants, such as this species may have lations might become extinct. area as a result of polyploidy (PAHL Niles Eldridge proposed another explain observations. The nature of California tarweed, evolved from an science is such that new evidence or Assessment are polyploids—indi- ih ployd ee), which is illustrated in hypothesis known as punctuated ancestral population LS Reproductive isolation new ideas can modify theories. in a short time. Portfolio Discuss the Reinforcement viduals that result Figure 15.17. Any species with a equilibrium. This hypothesis argues from mistakes made can result in speciation multiple of the normal set of chro- Abert and Kaibab squirrels of the Reinforce the concept of geo- during meiosis. As populations become increas- mosomes is known as a polyploid. Grand Canyon area. Have stu- graphic and reproductive isola- Loxodonta ingly distinct, reproductive isolation Mistakes during mitosis or meiosis africana dents prepare short summaries of tion by providing students with can arise. Reproductive isolation can result in polyploid individuals. Elephas maximus the discussion to put in their examples of the reproductive occurs when formerly interbreeding For example, if chromosomes do not portfolios. Summaries should behavior of closely related organ- organisms can no longer mate and separate properly during the first describe the environment that isms. For example, wood frogs, produce fertile offspring. meiotic division, diploid (2n) gametes each squirrel lives in, the charac- Rana sylvatica, and leopard frogs, There are different types of repro- can be produced instead of the nor- teristics of each species, and pos- Rana pipiens, are species that ductive isolation. One type occurs mal haploid (n) gametes. Polyploidy sible hypotheses for how the WORD Origin when the genetic material of the pop- results in immediate reproductive 0 evolved because of reproductive differences evolved. L2 isolation. Wood frogs usually polyploidy ulations becomes so different that isolation. When a polyploid mates From the Greek 1 breed in late March or early fertilization cannot occur. Some geo- with an individual of the normal word polys, meaning graphically separated populations of species, the resulting zygotes may not April, and leopard frogs usually “many.” Polyploid salamanders in California have this develop normally because of the dif- plants contain 2 Mammuthus breed in mid-April. primigenius multiple sets of type of reproductive isolation. ference in chromosome numbers. In chromosomes. Another type of reproductive isola- other cases, the zygotes develop into 3 Elephas ResourceResource tion is behavioral. For example, if adults that probably cannot repro- VIDEODISC one population of tree frogs mates in duce. However, polyploids within a Loxodonta The Secret ofP Life ManagerManager the fall, and another mates in the population may interbreed and form 4 Punctuated Equilibrium summer, these two populations will a separate species. Mammuthus Reteaching Skills Trans- 5 not mate with each other and are Polyploids can arise from within a Ago Millions of Years parency 24 and Master !7;BtE" reproductively isolated. species or from hybridization LS L1 ELL between species. Many flowering 6 Primelephas A change in chromosome plant species, as well as many impor- numbers and speciation tant crop plants, such as wheat, cot- Chromosomes can also play a role ton, apples, and bananas, originated P Ancestral species 55 million years ago in speciation. Many new species of by polyploidy.

418 THE THEORY OF EVOLUTION 15.2 MECHANISMS OF EVOLUTION 419 LS P Cultural Diversity MEETING INDIVIDUAL NEEDS

The Neutral Theory of Evolution The neutral theory was heavily debated Gifted Paleobiology, T. J. M. Schopf (ed.), Freeman, Explain to students the neutral theory of upon its presentation in 1968, but today it Linguistic Have the students research Cooper, and Co. Have students compare the LS evolution developed by Japanese biologist is viewed as an improvement of Darwinian speciation rate. Students should first evidence for both punctuated equilibrium theory because it provides testable predic- read Gould and Eldredge’s 1972 article con- and gradualism. Their report should draw a Mootoo Kimura. This theory holds that most P sequence changes that occur in DNA and tions about molecular evolution. The cerning punctuated equilibrium entitled conclusion about which hypothesis best sup- proteins do not affect how the proteins do strongest advocate of the neutral theory “Punctuated Equilibria: An alternative to ports the available evidence. L3 their job. In other words, most mutations is Japanese geneticist Tomoko Ohta, head phyletic gradualism,” found in Models in have a neutral affect on organisms. of Japan’s National Institute of Genetics. 418 LS 419

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LS Reinforcement Reteach Patterns of Evolution shown in Figure 15.19, evolved from Figure 15.20 Linguistic Reinforce the con- a single ancestral species that lived on Unrelated species of plants Visual-Spatial Have students cept of the niche by asking Biologists have observed different the Hawaiian Islands long ago. When such as the organ pipe cactus make a concept map to (a) and this Euphorbia (b) students to write brief autobi- patterns of evolution that occur an ancestral species evolves into an demonstrate how natural selec- throughout the world in different share a similar fleshy body ographies in which they describe array of species to fit a number of type and no leaves. tion acts on the variation of a where they live and something natural environments. These patterns diverse habitats, the result is called trait. L1 ELL about their school lives, activities, support the idea that natural selection adaptive radiation. is an important agent for evolution. and hobbies. L1 Adaptive radiation in both plants Extension and animals has occurred and contin- Diversity in new environments LinguisticP Have the students Concept Development ues to occur throughout the world An extraordinary diversity of and is common on islands. For exam- write a summary about how Use the student autobiographies Figure 15.19 unique plants and animals live or ple, the many species of finches that Darwin’s finches illustrate adap- to develop the niche concept. Evolutionary biolo- have lived on the Hawaiian Islands, Darwin observed on the Galapagos tive radiation. L2 gists have suggested Discuss some autobiographies among them a group of birds called Islands are a typical example of adap- LS that the ancestors of and point out that, just as no two all Hawaiian Island Hawaiian honeycreepers. This group tive radiation. b P autobiographies are alike, no two honeycreepers of birds is interesting because, Adaptive radiation is a type of Assessment a niches on EarthP are alike. Tie the migrated from North although similar in body size and divergent evolution, the pattern of Skill Have students ana- concepts of niche and struggle for America about 5 mil- shape, they differ sharply in color evolution in which species that once lyze the following data on existence to adaptive radiation. lion years ago. As and beak shape. Different species of were similar to an ancestral species becoming less alike as they adapt, For example, in Figure 15.20, you this ancestral bird LSrabbit population allele honeycreepers evolved to occupy diverge, or become increasingly dis- eventually resulting in new species. see a cactus of the family Cactaceae, frequencies.P population settled in an organ pipe cactus, that grows in Display the diverse Hawaiian their own niches. tinct. Divergent evolution occurs 1st generation: A = 0.5, a = 0.5 LS Different species can look alike the deserts of North and South niches, adaptive radi- Despite their differences, scientists when populations adapting to differ- 2nd generation: A = 0.6, a = 0.4 Display examples of convergent ation occurred. hypothesize that honeycreepers, as ent environmental conditions change, A pattern of evolution in which America and a plant of the family structures in organisms, such as distantly related organisms evolve Euphorbiaceae that looks like the 3rd generation: A = 0.7, a = 0.3 models or actual specimens of similar traits is called convergent cactus and lives in African deserts. 4th generation:LS A = 0.8, a = 0.2 5th generation: A = 0.9, a = 0.1 bird, bat, and insect wings. Amakihi evolution. Convergent evolution Although these plants are unrelated occurs when unrelated species species, their environments are simi- Have students describe what is happening in the population if A Ancestral occupy similar environments in dif- lar. You can see that they both have Lasan finch ferent parts of the world. Because fleshy bodies and no leaves. That represents an allele for white fur, Extinct they share similar environmental convergent evolution has apparently and a represents an allele for mamo Kauai pressures, they share similar pres- occurred in unrelated species, is fur- brown fur. L2 VIDEODISC Niihau Crested sures of natural selection. ther evidence for natural selection. honeycreeper Biology: The Dynamics Molokai of Life Oahu Adapted for Survival (Ch. 5) Maui Section Assessment 4 Close Disc 1, Side 2, 33 sec. Lanai Akialoa Understanding Main Ideas similar to those of hummingbirds. Explain how Discussion Kahoolawe 1. Explain why the evolution of resistance to these two organisms demonstrate the concept of !7^É" Hawaii antibiotics in bacteria is an example of convergent evolution. Discuss someP of the human cul- Akepa Apapane directional selection. tural adaptations that “shield” us SKILL REVIEWEVIEW 2. How can geographic isolation change a S R from the effects of natural selec- population’s gene pool? 6. Designing an Experiment Biologists have dis- tion, such as clothing, medicine, 3. Why is rapid evolutionary change more likely covered two species of squirrels living on oppo- Maui automobiles, etc. parrotbill to occur in small populations? site sides of the Grand Canyon. They hypothesize LS 4. How do gradualism and punctuated equilibrium that they both evolved from a recent, common 3 Assess Akiapolaau Liwi differ? How are they similar? ancestor that lived in the area before the Grand Canyon formed. What observations or experi- ResourceResource Check for Understanding Thinking Critically ments could provide evidence for this hypoth- Manager 5. Hummingbird moths are night-flying esis? For more help, refer to Practicing Scientific Manager Develop five questions about Grosbeak finch insects whose behavior and appearance are Methods in the Skill Handbook. types of natural selection and pat- Reinforcement and Study Akikiki Palila Guide, pp. 68-69 L2 terns of evolution. Have students Ou work in groups to answer the Content Mastery, pp. 73, 420 THE THEORY OF EVOLUTION 15.2 MECHANISMS OF EVOLUTION 421 75-76 L1 questions. L1 COOP LEARN P PortfolioPortfolio Section Assessment Adaptive Radiation deposited suddenly on an island that con- 1. Only bacteria that are totally resistant to 4. Gradualism takes a much longer time P LS Linguistic Have students write answers tained a swamp, a desert, a tropical rain antibiotics survive. than punctuated equilibrium, but they to the following for their portfolios. forest, and a snow-covered mountain. 2. It may result in different local environ- both result in evolution. Describe some adaptive changes that How do examples of adaptive radiation P ments for a separated population. 5. Although not closely related, they share might occur in a population of gray squir- support the concept of evolution by nat- P P Different adaptations are useful in differ- similar environments and have evolved LS rels over time if the population became ural selection? L2 P ent environments, and the gene pool will similar behaviors and appearances. in time reflect the differences. 6. Analyze the DNA, structure, and behavior LS 3. It occurs because of genetic drift and the of each. Examine fossils. 420 limited number of mates. LS 421 LS LS

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LS NTERNET INTERNET IN T INTERNET Natural Selection and 6. Count the number of pinto and allele over five generations. Plot Allelic Frequency navy beans remaining. Record this the frequency of the allele on the number in your data table. vertical axis and the number of P 7. Calculate the allelic frequencies the generation on the horizontal volution can be described as the change in allelic frequencies of a by dividing the number of beans axis. Use a different colored pen- Time Allotment E gene pool over time. Natural selection can place pressure on specific of one type by 100. Record these cil for each allele. AANALYZENALYZE ANDAND CCONCLUDEONCLUDE One class period phenotypes and cause a change in the frequency of the alleles that produce numbers in your data table. LS 8. Begin the next generation by plac- 1. Neither allele disappeared Process Skills the phenotypes. In this activity, you will simulate the effects of eagle pre- ing 100 beans into the bag. The dation on a population of rabbits, where GG represents the homozygous from the population because make and use tables, observe and proportions of pinto and navy beans the g allele is also in the het- infer, make and use graphs condition for gray fur, Gg is the heterozygous condition for gray fur, and should be the same as the percent- erozygous (Gg) rabbits. ages you calculated in step 7. gg represents the homozygous condition for white fur. 2. The graph shows an increase PPREPARATIONREPARATION 9. Repeat steps 3 through 8, collect- ing data for five generations. in the frequency of the G Alternative Materials 10. Go to the Glencoe Science Web allele and a decrease in the Beads or other small objects PPREPARATIONREPARATION Site at the address shown below frequency of the g allele due may be substituted for beans. to post your data. to natural selection against Problem Materials 11. Graph the frequencies of each white rabbits. How does natural selection affect colored pencils (2) 3. There would be less selective ResourceResource allelic frequency? paper bag Data Table pressure on white rabbits graph paper ManagerManager Allele G Allele g and, therefore, less decline in Objectives pinto beans Generation Number Percentage Frequency Number Percentage Frequency the frequency of the g allele. BioLab and MiniLab Work- In this BioLab, you will: white navy Simulate Start 50 50 0.50 50 50 0.50 4. sheets, pp. 73-74 L2 natural selection by using beans Students should notice little beans of two different colors. 1 difference in the allelic Calculate allelic frequencies over Skill 2 frequencies posted on the five generations. Handbook 3 Internet and the frequencies Demonstrate how natural selection Use the Skill 4 they calculated. By combin- can affect allelic frequencies over Handbook if you 5 ing data students may get time. need additional help more accurate results. Use the Internet to collect and com- with this lab. P pare data from other students. AANALYZENALYZE ANDAND CCONCLUDEONCLUDE Sharing Your Data

PPROCEDUREROCEDURE 1. Analyzing Data Did either allele amount of data? What problems To navigate LS disappear? Why or why not? might there be in using data from to the 1. Copy the data table shown on phenotypes, gray (genotypes GG 2. Thinking Critically What does the internet? Internet BioLabs choose the the next page. or Gg) and white (genotype gg). your graph show about allelic Biology: The Dynamics of Life 2. 5. frequencies and natural selection? Sharing Your Data Place 50 pinto beans and 50 white Examine your columns. Remove icon at Glencoe’s web site. navy beans into the paper bag. 25 percent of the gray rabbits and 3. Making Inferences What would Find this BioLab on the Click on the student site icon, 3. Shake the bag. Remove two beans. 100 percent of the white rabbits. happen to the allelic frequencies Glencoe Science Web Site then the BioLabs icon. The These represent one rabbit’s These numbers represent a ran- if the number of eagles declined? at www.glencoe.com/sec/science. Post your data from many trials sup- genotype. Set the pair aside, and dom selection pressure on your 4. Using the Internet Explain any dif- data in the data table provided for this continue to remove 49 more pairs. rabbit population. If the number ferences in allelic frequencies you BioLab. Use the additional data from other ports a student’s data and the 4. Arrange the beans on a flat you calculate is a fraction, remove observed between your data and the students on the Internet, and graph and conclusions the student may surface in two columns repre- a whole rabbit to make whole data from the Internet. What advan- analyze the combined data. draw from the data. senting the two possible rabbit numbers. tage is there to having a large

422 THE THEORY OF EVOLUTION 15.2 MECHANISMS OF EVOLUTION 423

PPROCEDUREROCEDURE Teaching Strategies Data and Observations Assessment Why or why not? No, because the gene pool would contain more g alleles that could produce Tell students that they will simulate nat- Make sure students are correctly calculating Knowledge Ask students whether more white rabbits. Use the Performance Task ural selection on a population to see how allelic frequency after each “generation” and allele frequencies would change as fast if Assessment List for Analyzing the Data in allelic frequency changes. recording these data in their data tables. only 60% of the white rabbits were removed PASC, p. 27. L2 You may wish to circulate during this Students should observe changes in the from the population each generation. activity to ensure that students are following allelic frequencies of the rabbit population. the procedure correctly. Student graphs should show an increase in Have students wash their hands after the frequency of the G allele and a decrease 422 handling the beans. in the g allele. 423

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LS Math Math Chapter 15 Assessment Chapter 15 Assessment Connection Connection Mathematics P and Evolution SSUMMARYUMMARY Main Ideas Purpose Section 15.1 Main Ideas Vocabulary Summary statements can be used by Students will examine the Hardy- After many years of experimentation and analogous structure (p. 409) students to review the major con- In the early 1900s, G. H. Hardy, a British In any sexually reproducing, large popula- Natural observation, Charles Darwin proposed the artificial selection (p. 403) cepts of the chapter. Weinberg principle and learn camouflage (p. 406) LS tion, genotype frequencies will remain constant idea that species originated through the about its implications. mathematician, and W. Weinberg, a German Selection and embryo (p. 410) if no mutations occur, random mating occurs, no doctor, independently discovered how the the Evidence process of natural selection. homologous structure (p. 408) Using the Vocabulary Teaching Strategies frequency of a trait’s alleles in a population could natural selection occurs, and no genes enter or Natural selection is a mechanism of change mimicry (p. 405) To reinforce chapter vocabulary, use be described mathematically. leave the population. for Evolution in populations. In a specific environment, natural selection (p. 403) Students should read this fea- vestigial structure (p. 410) the Content Mastery Booklet and ture after learning the concept of individuals with certain variations are Implications of the principle The Hardy- likely to survive, reproduce, and pass these the activities in the Interactive Tutor genetic equilibrium. Weinberg principle is useful for several reasons. variations to future generations. for Biology: The Dynamics of Life or uppose that in a population of pea plants, First, it explains that the genotypes in popula- Illustrate to students how this Evolution has been observed in the lab and the Glencoe Science Web Site: S36 plants are homozygous dominant for the tions tend to remain the same. Second, because a principle is used in practice. field, but much of the evidence for evolu- tall trait (TT), 48 plants are heterozygous tall recessive allele may be masked by its dominant www.glencoe.com/sec/science Stress that population geneticists tion has come from studies of fossils, (Tt), and 16 plants are short plants (tt). In the allele, the equation is useful for determining the use it to study the evolution in anatomy, and biochemistry. homozygous tall plants, there are (36) (2), or 72, recessive allele’s frequency in the population. populations. T alleles and in the heterozygous plants there Finally, the Hardy-Weinberg principle is useful All Chapter are 48 T alleles, for a total of 120 T alleles in in studying natural populations to determine Assessment Section 15.2 Main Ideas Vocabulary Connection to Biology the population. There are 48 t alleles in the how much natural selection may be occurring in adaptive radiation (p. 420) questions and answers have been No. The United States is not in heterozygous plants plus (16) (2), or 32, t alleles the population. Evolution can occur only when a popula- in the short plants, for a total of 80 t alleles in the Mechanisms tion’s genetic equilibrium changes. allelic frequency (p. 413) validated for accuracy and suitabil- genetic equilibrium because new convergent evolution (p. 421) population. The number of T and t alleles in the Mutation, genetic drift, and gene flow can ity by The Princeton Review. genes enter the population, mating is of Evolution directional selection (p. 416) population is 200. The frequency of T alleles is CONNECTION TO BIOLOGYIOLOGY change a population’s genetic equilibrium, probably not random, and natural disruptive selection (p. 416) 120/200 or 0.6, and the frequency of t alleles in The general population of the United States is especially in a small, isolated population. divergent evolution (p. 420) NDERSTANDING AIN DEAS selection affects the trait of human 80/200, or 0.4. getting taller. Assuming that height is a genetic Natural selection is usually a factor that gene pool (p. 413) UUNDERSTANDING MMAIN IIDEAS height. trait, does this observation violate the Hardy- causes change in established gene pools— genetic drift (p. 414) The Hardy-Weinberg principle The Hardy- Weinberg principle? Explain your answer. both large and small. genetic equilibrium (p. 413) 1. d Tying to Previous Knowledge Weinberg principle states that the frequency of geographic isolation (p. 417) The separation of populations by physical gradualism (p. 419) 2. a Review mutations and their the alleles for a trait in a stable population will To find out more about the barriers can lead to speciation. polyploid (p. 418) 3. d effects. Emphasize that mutations not vary. This statement is expressed as the equa- Hardy-Weinberg principle, There are many patterns of evolution in punctuated equilibrium (p. 419) affect genetic equilibrium by pro- tion p + q = 1, where p is the frequency of one visit the Glencoe Science Web Site. nature. These patterns support the idea reproductive isolation (p. 418) allele for the trait and q is the frequency of the speciation (p. 417) ducing new alleles for a trait and www.glencoe.com/sec/science that natural selection is an important other allele. The sum of the frequencies of the mechanism of evolution. stabilizing selection (p. 416) also change the frequency of alle- alleles always includes 100 percent of the alleles, les already in the population. For and is therefore stated as 1. example, the mutation that causes Squaring both sides of the equation produces the sickle-cell trait occurs sponta- the equation p2 + 2pq + q2 = 1. You can use this neously in about five out of 100 equation to determine the frequency of genotypes 2. What type of evolutionary evidence do fossils in a population: homozygous dominant individuals UUNDERSTANDINGNDERSTANDING MMAINAIN IIDEASDEAS million people. provide? (p2), heterozygous individuals (2pq), and recessive a. structural c. physiological individuals (q2). For example, in the pea plant 1. Two closely related species of squirrels live b. functional d. critical population described above, the frequency of the on opposite sides of the Grand Canyon. The genotypes would be ancestral species probably evolved into two 3. Which of the following is an example of species because of ______. direct evidence for evolution? (0.6) (0.6) + 2(0.6) (0.4) + (0.4) (0.4) = 1 a. structural isolation a. fossils The frequency of the homozygous tall genotype b. punctuated isolation b. embryology is 0.36, the heterozygous genotype is 0.48, and c. behavioral isolation c. vestigial structures the short genotype is 0.16. d. geographic isolation d. bacterial resistance to penicillin A population 424 THE THEORY OF EVOLUTION of penquins CHAPTER 15 ASSESSMENT 425

MEETING INDIVIDUAL NEEDS Resource Manager Gifted and have them calculate allelic frequency by Logical-Mathematical Have students counting the numbers of each genotype. VIDEOTAPE Chapter Assessment, pp. 85-90 calculate allelic frequency by having Change how many individuals are in the MindJogger Videoquizzes MindJogger Videoquizzes them work with a “population” of differ- population, as well as the numbers of each Chapter 15: The Theory of Evolution Computer Test Bank P ently shaped objects, such as pennies, pop- genotype in a population to produce new Have students work in groups as they play BDOL Interactive CD-ROM, Chapter 15 corn, beads, or beans. Tell students which practice problems. L3 the videoquiz game to review key chapter quiz object represents each particular genotype, concepts. LS 424 425

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LS Chapter 15 Assessment Chapter 15 Assessment Chapter 15 Assessment Chapter 15 Assessment

4. c 4. Which of the structures shown below is not 9. An example of a vestigial human structure is 23. It is easier to quantify differ- APPLYINGPPLYING MAINAIN IDEASDEAS AASSESSINGSSESSING KKNOWLEDGENOWLEDGE && SSKILLSKILLS 5. c homologous with the others? the ______. A M I ences in DNA than differences a. b. c. d. a. eye c. appendix 6. d 21. The structural characteristics of many The following graph shows leaf length in a in behavior or morphology. b. big toe d. ribs 7. b species, such as sharks, have changed little population of maple trees. 8. d 10. The fish and whale shown here are not over time. What evolutionary factors might 9. c closely related. Their structural similarities be affecting their stability? Leaf Lengths in a Maple Tree Population TTHINKINGHINKING CCRITICALLYRITICALLY appear to be the result of ______. 22. How might the bright colors of poisonous 10. b 100 11. punctuated equilibrium species aid in their survival? 24. In adaptive radiation, a general- 12. geographical isolation 23. Why is DNA a useful tool for determining 80 ized ancestor encounters an 13. gene pool possible relationships among the species of 60 area of many available niches a. adaptive radiation 14. natural selection 5. Which type of natural selection favors the organisms? and eventually diverges into b. convergent evolution 40 15. variations average individuals in a population? many species. This is an exam- c. divergent evolution Number of leaves a. directional c. stabilizing HINKINGHINKING RITICALLYRITICALLY 20 16. Mimicry d. punctuated equilibrium TT CC ple of divergent evolution, in 17. artificial b. disruptive d. divergent which species similar to ances- 11. The scientific hypothesis that explains 24. Observing and Inferring Describe adaptive 6. Which of the following pairs of terms is not 8 10121416182022 18. camouflage how an ancestral population of elephants radiation as a form of divergent evolution. tral species adapt to different related? Length of leaves in cm 19. homologous speciated quite rapidly after a long period environmental conditions. a. analogous structures—butterfly wings 25. Interpreting Data In a population of clams, 20. adaptive radiation of stability is ______. 25. T = 0.5; t = 0.5 b. evolution—natural selection let two alleles, T and t, represent shell color. Interpreting Data Study the graph and 12. Speciation due to physical barriers occurs as 26. 1. Natural selection; 2. Repro- c. vestigial structure—appendix The population consists of ten TT clams and answer the following questions. a result of ______. ten tt clams. What are the allelic frequencies ductive isolation; 3. Geographic d. adaptive radiation—convergent evolution 1. What was the range of leaf lengths? AAPPLYINGPPLYING MMAINAIN IIDEASDEAS 13. An understanding of population genetics of the T and t in the population? isolation; 4. Allelic frequency; 5. 7. Unlike any other birds, hummingbirds have a. 14 cm c. 20-100 cm depends on an understanding of the 26. Concept Mapping Speciation; 6. Gradualism; 7. wings that allow them to hover and to fly Complete the concept b. 8-22 cm d. 10-14 cm 21. Marine biomes are very stable backwards. This is an example of a ______, which is a collection of all the map by using the following vocabulary terms: Punctuated equilibrium and slow to change such envi- alleles in a population. allelic frequency, geographic isolation, 2. What was the average leaf length? adaptation. a. 8 cm c. 14 cm ronmental factors as salinity, 14. The mechanism Darwin proposed to explain gradualism, natural selection, punctuated a. physiological c. reproductive b. 12 cm d. 6 cm temperature, light penetration, b. structural d. embryological how species adapt to their environment over equilibrium, reproductive isolation, speciation. 3. What type of evolutionary pattern does etc. In stable environments, nat- 8. many generations is ______. Which of the following is a true statement 1. 2. 3. the graph most closely match? ural selection pressures tend to 15. The differences in the size of the peanuts in about evolution? a. artificial selection remain stable as well. Shark a. a bag are called ______. cause changes in Individuals evolve more slowly than b. stabilizing selection populations may be close to populations. 16. ______is the structural adaptation of 4. c. disruptive evolution genetic equilibrium. They have b. Individuals evolve; populations don’t. an organism that enables it to resemble d. directional evolution c. Individuals evolve by changing the gene another harmful or distasteful species. to produce stable relationships with both 4. Interpreting Data Use the graph below the environment and other pool. 17. The existence of desirable characteristics in 5. 1. b d. Populations evolve; individuals don’t. to explain what might be occurring in organisms in the environment. both crops and domestic animals results from occurs occurs this shark population. 2. b 22. Many adaptations are related the process called______selection. slowly in rapidly in 3. d to escaping from predators. 18. A subtle adaptation that allows an organism Variation in Tooth Size of Sharks TTESTEST––TTAKINGAKING TTIPIP 6. 7. 4. Directional selection is oc- Poisons are a natural defense. If to blend in with its surroundings is known curring in favor of larger a predator eats a brightly col- Wear a Watch as ______. teeth in sharks. ored insect and becomes ill, it If you are taking a timed test, you should make 19. The wings of bats and the forelimbs of CD-ROM

will avoid such an organism the sure that you pace yourself and do not spend too crocodiles are examples of ______For additional review, use the assessment Sharks much time on any one question, but don’t spend structures. options for this chapter found on the Biology: The next time. Bright colors indicate time staring at the clock. When the test begins, 20. A species may find its way to an island and Dynamics of Life Interactive CD-ROM and on the that the organism may be poi- place your watch on the desk and check it after Glencoe Science Web Site. Tooth size sonous and deter predators. each section of the test. then evolve into many species in a process www.glencoe.com/sec/science called ______.

426 CHAPTER 15 ASSESSMENT CHAPTER 15 ASSESSMENT 427

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