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Q How could evolution lead to this? The star-nosed mole has a pink snout that is espe- cially good at finding food. The snout’s 22 fingerlike rays can touch up to 12 objects in just one second. The mole also uses strong paddle-shaped feet for burrowing, and its large ear openings give it excellent hearing. These special traits make up for its poor vision—which it doesn’t really need underground.

R E a d IN G T o o lb o x This reading tool can help you learn the material in the following pages.

USING LANGUAGE Your Turn Hypothesis or Theory? In everyday language, there Use what you have learned about a hypothesis and a is little difference between a hypothesis and a theory. But theory to answer the following questions. in science, the meanings of these words are more distinct. 1. List some scientific theories that you have heard of. A hypothesis is a specific, testable prediction for a limited 2. Make a simple concept map or Venn diagram to show set of conditions. A theory is a general explanation for a the relationship between hypotheses and theories. broad range of data. A theory can include hypotheses 3. The word theory may also be used to describe general that have been tested and can also be used to generate trends and areas of active investigation in a scientific new hypotheses. The strongest scientific theories explain field. In this context, what does the term evolutionary the broadest range of data and incorporate many theory mean? well-tested hypotheses.

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10.1 Early Ideas About Evolution

2B, 3F, 7B Key Concept there were theories of biological and geologic change before Darwin. VOCABULARY MAIN IDEAS evolution Early scientists proposed ideas about evolution. species Theories of geologic change set the stage for Darwin’s theory. fossil catastrophism gradualism Connect to Your World uniformitarianism Why are there so many kinds of living things, such as the strange looking star-nosed mole? Earth is home to millions of species, from bacteria to plants to ocean organ-

2B know that hypotheses isms that look like they came from science fiction. The search for reasons for Earth’s are tentative and testable state- great biological diversity was aided in the 1800s, when Charles Darwin proposed his ments that must be capable of being supported or not supported theory of evolution by natural selection. But long before Darwin, evolution had been by observational evidence; 3F the focus of talk among scholars. research and describe the history of biology and contributions of scientists; 7B analyze and evaluate scientific explanations concerning MAIN IDEA 2B, 3F any data of sudden appearance, stasis, and sequential nature of Early scientists proposed ideas about evolution. groups in the fossil record Although Darwin rightly deserves much of the credit for evolutionary theory as we know it today, he was not the first person to come up with the idea. Evolution is the process of biological change by which descendants come to differ from their ancestors. This concept had been discussed for more than 100 years when Darwin proposed his theory of the way evolution works. Today, evolution is a central theme in all fields of biology. The 1700s were a time of great advances in intellectual thought. Many fields of science developed new ways of looking at the world during that century. Four scientists in particular are important. They not only made valuable con- tributions to biology in general, but they also laid the foundations upon which Darwin would later build his ideas. FIGURE 1.1 highlights the work of some of READING TOOLBox these early scientists. TAKING NOTES Carolus Linnaeus In the 1700s, the Swedish botanist Carolus Linnaeus devel- Create a chart with a column oped a classification system for all types of organisms known at the time. for the scientists mentioned in this section and a second Although Linnaeus used his system to group organisms by their similarities, column for their contributions the system also reflects evolutionary relationships. This system is still in use by to evolutionary theory. scientists today. Years into his career, Linnaeus abandoned the common belief Scientist Contribution of the time that organisms were fixed and did not change. He proposed Linnaeus instead that some might have arisen through hybridization—a crossing that he Buffon could observe through experiments with varieties, or species, of plants. A species is a group of organisms that are closely related and can mate to reproduce fertile offspring.

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Georges-Louis Leclerc de Buffon Buffon, a French naturalist of the 1700s, CONNECT TO challenged many of the accepted ideas of the day. Based on evidence of past Scientific Process life on Earth, he proposed that species shared ancestors instead of arising Recall from the chapter Biology separately. Buffon also rejected the common idea of the time that Earth was in the 21st Century that in every only 6000 years old. He suggested that it was much older. This argument scientific field, knowledge is built was similar to that of Charles Lyell, a geologist whose work helped inspire upon evidence gathered by earlier scientists. Darwin’s writings. You will read more about Lyell later in this section. Erasmus Darwin Born in 1731, Charles Darwin’s grandfather was a respected English doctor and a poet. He proposed that all living things were descended from a common ancestor and that more-complex forms of life arose from less- complex forms. This idea was expanded upon 65 years later by his grandson. Jean-Baptiste Lamarck In 1809, the year of Darwin’s birth, a French naturalist named Lamarck proposed that all organisms evolved toward perfection and complexity. Like other scientists of the time, he did not think that species became extinct. Instead, he reasoned that they must have evolved into different forms. Lamarck proposed that changes in an environment caused an organism’s behavior to change, leading to greater use or disuse of a structure or organ. The structure would become larger or smaller as a result. The organism would pass on these changes to its offspring. For example, Lamarck thought that the long necks of giraffes evolved as generations of giraffes reached for leaves higher in the trees. Lamarck’s idea is known as the inheritance of acquired characteristics.

FIGURE 1.1 Early Naturalists Evolutionary thought, like all scientific inquiry, draws heavily upon its history. The published works of these scientists contributed important ideas prior to Darwin’s theory.

1735 Systema Naturae 1749 Histoire Naturelle 1794–1796 Zoonomia 1809 Philosophie Zoologique Carolus Linnaeus proposed a Georges Buffon discussed Erasmus Darwin considered how Jean-Baptiste Lamarck pre- new system of organization for important ideas about relation- organisms could evolve through sented evolution as occurring plants, animals, and minerals ships among organisms, sources mechanisms such as competition. due to environmental change based upon their similarities. of biological variation, and the over long periods of time. possibility of evolution.

Summarize Explain why Darwin was not the first scientist to consider evolution. 2B, 3F (l) Natural History Museum, London/The Bridgeman Art Library; (cl) Photo © Christie’s Images/The Bridgeman Art Library; Images/The Bridgeman Photo © Christie’s Art Library; (cl) London/The Bridgeman (l) Natural History Museum, York New Art Library;Art Library; (r) ©The Granger Collection, (cr) Private Collection /The Bridgeman Bridgeman France/Giraudon/The Paris, (c) Bibliotheque Nationale,

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any layer above it. given layer was deposited before sequence oflayered rocks, a superposition. Itstates that ina what we know asthelaw of Cuvier based histhinkingon E tions andtheformation ofall landforms. once believed responsible for mass extinc- examples ofcatastrophic events that were Volcanoes, andearthquakes floods, are CA Ideas from geology played arole inthedevelopment ofDarwin’s theory. ar FIGURE 1.2 Unit 4:Evolution Compare and Contrast CO T t AS NN h T S EC RO cie T P

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The theory of catastrophism (kuh-TAS-truh-fihz-uhm) states that natural READING TOOLBox disasters such as floods and volcanic eruptions have happened often during Earth’s long history. These events shaped landforms and caused species to VOCABULARY The names of these geologic become extinct in the process. Cuvier argued that the appearance of new theories can be broken down species in each rock layer resulted from other species moving into the area into familiar words. from elsewhere after each catastrophic event. • Catastrophe means “sudden disaster.” In the late 1700s, the Scottish geologist James Hutton proposed that the • Gradual means “moving or changes he observed in landforms resulted from slow changes over a long period changing slowly.” of time, a principle that became known as gradualism (GRAJ-oo-uh-lihz-uhm). • Uniform means “always staying the same.” He argued that the laying down of soil or the creation of canyons by rivers cutting through rock was not the result of large-scale events. He believed, rather, that they resulted from slow processes that had happened in the past. This idea has become so important to evolution that today the term gradual- ism is often used to mean the gradual change of a species through evolution. VISUAL VOCAB One of the leading supporters of Uniformitarianism proposes that present geologic processes are the key the argument for an ancient Earth to the past. was the English geologist Charles CONNECT TO Lyell. In Principles of Geology, pub- Scientific Process lished in the 1830s, Lyell expanded Every layer of rock Hutton’s theory of gradualism into was formed by the Recall from the chapter Biology in the 21st Century that in the theory of uniformitarianism uniform laying down of sediment that still science, the term theory (yoo-nuh-fawr-mih-TAIR-ee-uh- occurs today. describes a well-supported nihz-uhm). This theory states that explanation that incorporates observations, inferences, and the geologic processes that shape tested hypotheses. Earth are uniform through time. Lyell observed processes that made small changes in Earth’s features. He inferred that similar changes had happened in the past. Uniformitarianism combines Hutton’s idea of gradual change over time with Lyell’s observations that such changes have occurred at a constant rate and are ongoing. Uniformitarianism soon replaced catastrophism as the favored theory of geologic change. Lyell’s theory greatly affected the scientific community—particularly a young English naturalist named Charles Darwin. Compare What important concepts about Earth did Hutton and Lyell agree upon? ©Richard Hamilton Smith/Corbis

Self-check Online HMDScience.com 10.1 Formative Assessment GO ONLINE Reviewing Main Ideas Critical thinking CONNECT TO 1. Briefly describe two ideas about 3. Contrast What are the key differ- Genetics evolution that were proposed by ences between the theories of 5. How can you use the scientists in the 18th century. gradualism and catastrophism? concept of genetic inheri- 2B, 3f 4. Apply Why are the ideas that Earth tance to disprove Lamarck’s 2. What ideas in Lyell’s theory of undergoes change and is billions idea of the inheritance of uniformitarianism were important of years old important for acquired characteristics? for evolutionary theory? 3f evolutionary theory? 7b

Chapter 10: Principles of Evolution 289 CorrectionKey=A DO NOT EDIT--Changes mustbemadethrough “File info” Unit 290 adaptation variation VOCABULARY among species development ofdiversity inand selection to adaptation andto the evaluate therelationship ofnatural developmental; 7 including anatomical, molecular, and biogeography, andhomologies, is provided by thefossil record, of common ancestry amonggroups analyze andevaluate how evidence contributions ofscientists; 7A the history and ofbiology F works. 1859 evidence more IGURE

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y similar species that he observed in all his travels. inall thatsimilar species heIn observed biology, Darwin, shown in Darwin, able to adapt to surroundings. their An werebeaks found or where were insects fruits widely available. of large, hard-shelled nuts, of species finchwith those more while delicate short plants. Similarly, finches with strong, lived inareas thick beaks with alot toises, with shorter their necks and legs, lived inwet areas rich inmosses and have long necks and legs, lived inareas with alot plants. of tall Domed tor- lead tolead genetic change inapopulation over time. organism to and better survive reproduce inits environment. Adaptations can islands’ looked different species from on those nearest the mainland. one island looked different from on those nearby islands and that many of the same (intra species noted variation). thatspecific found Darwin species the on ofbers different (inter species variation)specific or among individuals of the group inthe als to which it belongs. Variation either can among occur mem- difference physical inthe traits of an individual from of those other individu- and diets, as shown in America. Some differences well suited seemed to animals’ the environments able in the Galápagos Islands, an island chain off the coast of Ecuador in South MAI lápagos Islands? lápagos MAI C Darwin Darwin o The The dif N n N

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FIGURE 2.2 Adaptations Within Species Galápagos tortoises (Geochelone elephantopus) are evidence that species can adapt to their environments. N 70˚W EW S VENEZUELA

PANAMA COLOMBIA

0˚ Equator Galápagos ECUADOR Islands PACIFIC OCEAN BRAZIL PERU 10˚S 0 500 miles Domed tortoises have a short neck and short Saddle-backed tortoises have a high shell edge, 0 500 kilometers legs, and live in areas with low vegetation. allowing them to stretch their long necks. 90˚W 80˚W BOLIVIA Explain Why do these tortoises of the same species look different? Galápagos Islands MAIN IDEA 3F, 7a Darwin observed fossil and geologic evidence MapQuest supporting an ancient Earth. McDougal-Littel, Biology Program '05 Galapagos Blow out map Biology IDEO On his voyage, Darwin found fossil evidence of species changing over time. V CLIP In Argentina, he found fossils of huge animals, such as Glyptodon, a giant 2nd proof date: 9/27/05 HMDScience.com armadillo. The fact that these fossils looked like living species suggested that modern animals might have some relationship to fossil forms. These fossils GO ONLINE suggested that, in order for such changes to occur, Earth must be much more Darwin and His Work than 6000 years old. During his voyage, Darwin also found fossil shells of marine organisms high up in the Andes mountains. Darwin later experienced an earthquake during his voyage and saw firsthand the result: land that had been underwater was moved above sea level. This experience explained what he saw in the Andes. Darwin’s observations on his voyage supported Lyell’s theory that daily geologic processes can add up to great change over a long period of time. Darwin later extended the ideas of an old Earth and slow, gradual change to the evolution of organisms. This became known as evolutionary gradualism. Infer What could account for fossils of marine organisms being found on top of (tl) ©Stephen Photography Frink/Corbis; (tc) ©Mark Tortoise Jones/Roving modern-day mountain ranges?

Self‑check Online HMDScience.com 10.2 Formative Assessment GO ONLINE Reviewing Main Ideas Critical thinking CONNECT TO 1. What accounts for the variation 3. Apply Explain how wings are an Ecology Darwin observed among island adaptation for birds. 7e 5. Some birds in the Galápagos species? 7e 4. Synthesize How did Darwin’s Islands build nests in trees, 2. What did Darwin learn from the observations support Lyell’s theory while others hide eggs in fossils that he observed on of an ancient Earth undergoing rock crevices. What could his voyage? 3F, 7a continual geologic change? account for this difference in 3f, 7a nesting behaviors? 7e

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10.3 Theory of Natural Selection

2G, 3F, 7C, 7D, Key Concept Darwin proposed natural selection as a mechanism 7E for evolution. VOCABULARY MAIN IDEAS artificial selection Several key insights led to Darwin’s idea for natural selection. heritability Natural selection explains how evolution can occur. natural selection Natural selection acts on existing variation. population fitness Connect to Your World Have you ever had an experience that changed your outlook or your opinion about 2G analyze, evaluate, make inferences, and predict trends from an issue? Darwin began his voyage thinking that species could not change. However, data; 3F research and describe the his experiences during the five-year journey changed the way he thought about life history of biology and contributions of scientists; 7C analyze and and evolution. He became convinced that evolution occurs. But he had yet to evaluate how natural selection determine how it could happen. produces change in populations, not individuals; 7D analyze and evaluate how the elements of natural selec- 3F, 7C, 7D, 7E tion, including inherited variation, MAIN IDEA the potential of a population to produce more offspring than can Several key insights led to Darwin’s idea for survive, and a finite supply of environmental resources, result in natural selection. differential reproductive success; 7E analyze and evaluate the After his voyage, Darwin spent more than 20 years conducting research while relationship of natural selection to adaptation and to the development thinking about the way evolution occurs. Although he had traveled the world, of diversity in and among species Darwin also found great insight in his home country of England. One important influence on Darwin’s research was the work of farmers and breeders. Artificial Selection Darwin noticed a lot of variation in domesticated plants and animals. The populations of domesticated species seemed to show variation in traits that were not shown in their wild relatives. Through selection of certain traits, breeders could produce a great amount of diversity. The process by which humans change a species by breeding it for certain traits is called artificial selection. In this process, humans make use of the genetic variation in plants and animals by acting as the selective agent. That is, humans determine which traits are favorable and then breed individuals that show those traits. To explore this idea, Darwin turned to the hobby of breeding pigeons. Although Darwin had no knowledge of genetics, he had noticed certain traits being selected in animals such as livestock and pets. For thousands of years, humans had been breeding pigeons that showed many different traits, such as those in FIGURE 3.1. In order for artificial—or natural—selection to occur, the trait must be heritable. Heritability (her-ih-tuh‑BIHL-uh-tee) is the ability of a trait to be passed down from one generation to the next.

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Darwin compared what he learned about breeding to his ideas on adaptation. In artificial selection, features such as reversed neck feathers, large crops, or extra tail feathers are favored over generations only if these traits are liked by breeders. However, breeders might also select against features that are not desirable or “useful.” During artificial selection, humans act as the selective agent. In nature, however, the environment creates the selective pressure that determines if a trait is passed on or not. Darwin used this line of thinking for his theory of natural selection. Natural selection is a mechanism by which individuals that have inherited beneficial adaptations show differential reproductive success. In other words—they tend to produce more offspring on average than do other individuals. In nature, the environment is the selective agent. Therefore, in nature, characteristics are selected only if they give advantages to individuals in the environment as it is right now. Furthermore, Darwin reasoned, desir- able breeds are not produced immediately. He knew that it sometimes took many generations for breeders to produce the varieties he had observed.

Struggle for Survival Another important idea came from English economist Thomas Malthus. Malthus had proposed that resources such as food, water, and shelter were natural limits to population growth. That is, human populations would grow geometrically if resources were unlimited. Instead, disease and a limited food

FIGURE 3.1 Artificial Selection of Pigeon Traits For thousands of years, new varieties of organisms, such as pigeons, have resulted from selective breeding for particular traits. Selectively bred pigeons

neck feathers Jacobins are bred for their ©Australian National Pigeon Association ©Australian National Pigeon reversed neck feathers.

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tail feathers Voorburg Shield Cropper pigeon, Jacobin pigeon, Fantail pigeon Fantail Jacobin pigeon, Shield Cropper pigeon, Voorburg

Fantails are bred to Croppers are bred for have many tail feathers. their inflatable crop.

Connect What other species of organisms are often subjects of artificial selection? (bl) ©Lynda Richardson/Corbis; (bl) ©Lynda

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supply kept the population smaller. Darwin reasoned that a similar struggle took place in nature. If resources are limited and organisms have more offspring than could survive, why do some individuals, and not others, READING TOOLBox survive? Darwin found his answer in the variation he had seen within populations. VOCABULARY The term descent is used in A population is all the individuals of a species that live in an area. Darwin evolution to mean the passing had noticed in the Galápagos Islands that in any population, such as the of genetic information from tortoises or the finches, some individuals had variations that were particularly generation to generation. well-suited to their environment. He proposed that these adaptations arose over many generations. Darwin called this process of evolution “descent with modification.” Explain How did Malthus’s economic theory influence Darwin? 3F

MAIN IDEA 3F, 7D, 7E Natural selection explains how evolution can occur. Charles Darwin was not the only person to develop a theory to explain how evolution may take place. An English naturalist named Alfred Russel Wallace independently developed a theory very similar to Darwin’s. Both Darwin and Wallace had studied the huge diversity of plants and animals in the tropics, and both had studied the fossil record. In 1858, the ideas of Darwin and Wallace were presented to an important group of scientists in London. The next year, Darwin published his ideas in the book On the Origin of Species by READING TOOLBox Means of Natural Selection.

TAKING NOTES There are four main principles to the theory of natural selection: variation, Write a sentence in your own overproduction, adaptation, and descent with modification. words that summarizes each of • Variation The heritable differences, or variations, that exist in every the four principles of natural population are the basis for natural selection. The differences among selection. individuals result from differences in the genetic material of the organisms, variation whether inherited from a parent or resulting from a genetic mutation. overproduction • Overproduction While having many offspring raises the chance that some adaptation will survive, it also results in competition between offspring for resources. descent with modification • Adaptation Sometimes a certain variation allows an individual to survive better than other individuals it competes against in its environment. More successful individuals are “naturally selected” to live longer and to produce more offspring that share those adaptations for their environment. • Descent with modification Over time, natural selection will result in species with adaptations that are well suited for survival and reproduction in an environment. More individuals will have the trait in every following generation, as long as the environmental conditions continue to remain beneficial for that trait. A well-studied example of natural selection in jaguars is shown in FIGURE 3.2. About 11,000 years ago, many species faced extinction. Large cats, including jaguars, faced a shortage of food due to the changing climate of that time. There were fewer mammals to eat, so the jaguars had to eat reptiles. In

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the jaguar population, there were variations of jaw and tooth size that became READING TOOLBox important for survival. Like many other species, jaguars can produce more offspring than can be supported by the environment. Jaguars with the biggest VOCABULARY In everyday language, fitness jaws and teeth could prey more easily on the shelled reptiles. Because jaw size means “physically fit.” In and tooth size are heritable traits and were beneficial, large jaws and teeth biology, however, fitness is became adaptations for this population. The jaguars’ descendants showed related to reproductive success. modifications, or changes, over time. In biology, the term fitness is a measure of the ability to survive and produce more offspring relative to other members of the population in a given environment. After the change in climate, jaguars that had larger teeth and jaws had a higher fitness than other jaguars in the population. Jaguars that ate less didn’t necessarily all die or stop producing altogether; they just reproduced a little less. Today, large teeth and jaws are considered typical traits of jaguars. Compare and Contrast What are the similarities and differences between natural selection and artificial selection? Biology HMDScience.com FIGURE 3.2 The Principles of Natural Selection GO ONLINE Certain traits become more common in a population Principles of Natural through the process of natural selection. Selection

jaguar 2 jaguar 1

overproduction variation A jaguar may produce many offspring, but not all will Some jaguars, such as jaguar 1 survive due to competition for resources. shown here, may be born with slightly larger jaws and teeth due to natural variation in the population. Some jaguar skull 2 adaptation variations are heritable. jaguar skull 1 Jaguars with larger jaws and teeth are able to eat shelled reptiles. These jaguars are more likely to survive and to have more offspring than jaguars that can eat descent with modification only mammals. Because large teeth and jaws are heritable traits, they become more common characteristics in the population.

Summarize How did large jaws and teeth become typical characteristics of jaguars? 7e

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DATA ANALYSIS 2g Interpreting Line Graphs Scientists used mice to study whether exercise ability Graph 1. selection of exercise ability can improve in animals over several generations. In this experiment, mice were artificially selected for increased 12,000 wheel-running behavior. The mice that were able to do Control group the most wheel running were selected to breed the next 10,000 generation. The control group represents generations of Experimental group mice that were allowed to breed randomly. 8,000 • The x-axis shows different generations of mice, from Generation 1 to Generation 9. 6,000 • The y-axis shows the number of revolutions the mice ran on the wheel per day. • The solid blue line represents the control group, in 4,000 which generations of mice were allowed to breed per day Number of revolutions randomly. 2,000 • The dotted orange line represents the generations 1 2 3 4 5 6 7 8 9 of mice that were artificially selected based on Generations

their wheel‑running ability. This is the experimental Source: Swallow et. al, Behavior Genetics 28:3. group.

1. Interpret What is the difference in results between the mice in the control group and the mice in the experimental group? 2. Predict Use the trend in the data to make a general prediction about the number of revolutions on the wheel per day for mice in Generation 10 of the experimental group.

MAIN IDEA 3F, 7C, 7D, 7E Natural selection acts on existing variation. Biology Natural selection acts on phenotypes, or physical traits, rather than on HMDScience.com genetic material itself. New alleles are not made by natural selection—the­­ y GO ONLINE occur by genetic mutations. Natural selection can act only on traits that Natural Selection already exist. Changing Environments Ecologists Peter and Rosemary Grant observed an example of natural selec- tion acting on existing traits within a population of medium ground finches on one of the Galápagos Islands. A drought in 1977 suddenly reduced the amount of small, soft seeds that the finches preferred. However, there were still plenty of large, tough-shelled seeds. Because the large-beaked finches in the population were able to crack the large, tough seeds, they did not starve. The next year, the Grants noted a big increase of large-beaked hatchlings. In contrast, most of the finches with small beaks had died.

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(tr) ©AP/Wide World Photos; (br) ©Keren Su/Corbis E 10.3 xplain in your fingers, plus thumblike asmall structure. The panda’s “thumb,” shown ata closelook paw the reveals that it has six digits: five digits that resemble shoots,holdbamboo they shoots the as you would hold acarrot. However, have astructure that wrist intheir like athumb. acts As pandas eat Forcase. example, some structures may on take functions. new Pandas viduals that are suited perfectly to surroundings. their This is not the adaptive characteristics down passed over along result time inindi- One mistake people make about natural isthat to selection think Adaptations as Compromises today may adisadvantage be future. inthe birds. With evolution, atrait that is an advantage production and of small-beaked seeds small, soft an unusually conditions These wet period. favored supply the 1984, when of large went seeds down after finches on Galápagos this Island kept rising until The numbersbecome beneficial. of large-beaked future generations. environment,in the and thus on was passed to favorablebecame of because for achange survival ob bone and athumb. tothan for function needed Instead, wrist. the it functions as awrist both thumb It does. not is also atypical bone, wrist as bone the is clearly longer thumb,true it because not does have separate bones and joints as ahuman and position, bone this functions like ahuman thumb. It is not considered a bigger bones wrist had an advantage ineating bamboo. of its Because size pandas digits had like fivetoday’s full bears,but early those pandas with 3. 2. 1. Re

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CONN years? forthe same of millions explain aspeciesthat remains generations. How would you organisms change over environment aff You have learned that the Chapter 10:Principles of Evolution Chapter 10:Principles of Evolution HMDScience.com Self-check Online g E CT TO y

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vestigial structure analogous structure homologous structure biogeography VOCABULARY nature ofgroups inthefossil record appearance, stasis, andsequential concerning anydata ofsudden evaluate scientific explanations developmental; 7 including anatomical, molecular, and biogeography, andhomologies, is provided by thefossil record, common ancestry amonggroups and evaluate how evidence of tributions ofscientists; 7 the history andcon- ofbiology earl floor ofanancient sea.floor oceans, thissite isactually the Although far from modern-day this loose rock bedinOhio. is now extinct, was found in Figure 4.1 Unit 4:Evolution y marineinvertebrate that 3Fresearch anddescribe 10.4

This trilobite, an B anal 3F, 7 yze and A A anal , 7 Evidence ofEvolution B yze from several sources. Evidence for evolution Darwin’s in came time comes fr many sources, all ofwhichhelpedto strengthen hisunderstanding ofevolution. these pieces helpyou to understand thetopic. Darwinalso drew information from the library, theInternet, your teachers, ormaybe even your friends.Together, all need to gather information. Thedifferent pieces ofinformation mightcome from Whenever you needto complete anassignment onanunfamiliar topic, you first Connect to Your World K ey

closely resemble on species nearest the mainland. continent. He extended proposing observation, this that island most species animals looked like, but were not identical to, on species South the American that duringRecall Beagle the Geography record supported Darwin’s concept of descent with modification. ­How record of natural events such as earthquakes, not as proof of evolution. ­inte organism the when it came from was alive. about think also They its age, its location, and what environment the was like over time. Scientists study who fossils on focus more than just fossil the itself. Even scholars before studying Darwin, fossils that knew organisms changed Fossils geography, developmental similarities, and anatomy. for evolution. The most important and convincing support came from fossils, found from evidence Darwin range awide of sources to support his argument in the upper,in the or newer, layers. during Geologists were time this mostly fossil organisms bottom, inthe or older, layers were more primitive than those found insome layers of rock and not others. Later studies suggested that the MAI MAI C

In th o Structural patterns are cluesto thehistory ofaspecies. Evidence for evolution inDarwin’s timecame from several sources. rested order inthe inwhich fossils were found within rock strata as a N ever, sequential the nature of fossil groups and other findings fossil inthe n N ID ce IDEAS om manysources. e late 1700s,geologists wondered of why types fossils certain were pt EA

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FIGURE 4.2 Variation in Galápagos Finches

Finches on certain Galápagos Islands live in different Small tree finch environments and have beaks of different sizes Camarhynchus parvulus and shapes. Species in the genus Cama­ rhynchus have biting strength at the tips of their beaks, which

91 °W is useful for tearing vegetation.

0° C a n N a Isla San Salvador l (Santiago, James) I EW sa b e S la Isla Fernandina (Narborough) Large cactus finch Isla Isabela Isla Santa Cruz (Albemarle) (Indefatigable) Geospiza conirostris 1°S Isla San Cristóbal Isla Santa María (Chatham) Species in the genus 0 25 50 miles (Floreana, Charles) Geospiza have thick Isla Española 0 25 50 kilometers (Hood) beaks and can feed on large, hard seeds that require strength for crushing. Infer What different environmental conditions might be found on the islands that these two species of finch inhabit?

Darwin hypothesized that at some point in the past, some individuals from the South American mainland had migrated to the islands. This relationship between island and mainland species is today an important principle of biogeography, the study of the distribution of organisms around the world. Different ecosystems on each island—with different plants, climates, and predators—had favored different traits in these migrants. Over time, these new traits became well established in the separate island populations, since the islands were too far apart for mating to occur. One clear example of local adaptation is found in what are now known as Darwin’s finches. The finches from the Galápagos Islands, shown in fIGURE 4.2, have distinct-looking beaks, as well as different habits, diets, and behaviors that evolved after generations of adaptation to specific island habitats. However, they all share a common ancestor from the South American mainland. Since Darwin’s time, the same pattern of evolution on islands has been studied in many living things, such as fruit flies and honeycreepers found among the Hawaiian Islands. A 2011 study analyzing DNA from all living species of Hawaiian honeycreepers indicated that they are all likely descended from a population of rosefinches that arrived in Hawaii from Asia sometime between 7.2 million and 5.8 million years ago. The evidence from this study also indicated that nearly all species of honeycreepers likely diverged between 5.8 million and 2.4 million years ago, the same period during which the island of Oahu first appeared. Like the honeycreepers, most species of plants and ­animals on the Hawaiian Islands are not found anywhere else on Earth, and the age of these species is close to the age of the islands on which they live. Developmental Similarities A study proposing a relationship between barnacles, which are fixed in place as adults, and crabs, which are mobile at all stages in their life cycles, fascinated Darwin. Darwin collected specimens of barnacles over many years of res­ earch.

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in humans. protects thebody andsupports about how theaxial skeleton Movement to findoutmore Protection, and Support, Refer to section1ofthechapter BODY S Unit 4:Evolution CO NN EC T RUC T

T O Larva T URE win that they share acommon ancestor. differ Figure 4.3 Ernst Haeckel. Agreat follower of Darwin’s theory, Haeckel maintained that Schöpfungsgeschichte) (Natürliche Creation subject the ofbeen controversy since late the Natural 1800s,when of History Dorsal nerve cord vertebrates, notochord the develops into of part vertebral the column. fish-like lancelet, keep notochords their throughout lives, their inthe while which phylum the Chordata is named. Primitive chordates, such as the Notochord arches develop into bones, and nerves, the other structures of throat. the However, inhumans, arch fifth the disappears and third, the fourth, and sixth face,the ears, and jaws. In adult two the fish, lower arches gills. become the ryn Pharyngeal arches spine that not does extend to outside. the majority of humans only have a“tailbone” at end the of coccyx) (the the humancases, babies are with born ashort made tail of tissue, soft but vast the generally into absorbed other the tissues prior to In birth. extremely rare developas they abony skeleton. axial However, inhuman is embryos, tail the animalthe and extends into tail. aflexible Many vertebrates retain tails their vertebrates lies ahollow cord nerve that along runs dorsal, the or back side, of mal characteristics. For example, embryos the of birds, fish, reptiles, and mam tio are similar inappearance. free-swimmingtheir larvae very observa These F In making his observations of crustaceans, he these noticed, as shown in IGURE ently, they can look very similar aslarvae. Thissuggested to Dar- ns formed an important of part Darwin’s for evidence common descent. The s geal arches,geal separated by slits. The upper arches develop into structures of s all haves all support aflexible anotochord, rod backs intheir called for 4.3

Although adult crabs andbarnacles look andbehave very imilarity of features invertebrate embryos, shown in , that although adult crabs and barnacles are significantly different,

In th e same fashion, embryos of vertebrates share many similar

Wit All c All hin notochord the of lancelets the both and embryonic hordate embryos have six structures known as pha Adult crab was published by scientist German Adult barnacles F IGURE 4.4 , has has , ­ ­ ­

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(bl) ©MedicalRF.com/Corbis; (bc) ©Education Images/UIG/Getty Images; (br) ©Dr. Keith Wheeler/Photo Researchers, Inc. Evaluate ve Analyze F of the same structuresof thesame can beseen at various stages intheirdeveloping embryos. Although humans,pigs, andchickens appear different from each other asadults, several IGURE vertebrates and other organisms evolved from distant common ancestors. chapterthe Invertebrate Diversity. Evidence such as suggests this that plan.basic body genes, These Hox the similar genes ofset very that development direct the of structures from body a considerationunder serious by scientists. recovered from accusations the of fraud. His recapitulation is no longer theory with eachevidence of five the editions of his reputation his book, never to make comparisons.observers Although Haeckel and revised new added his drawings that he deliberately reduced to them similar sizes to enable graphs. scientists Other argued that Haeckel openly stated captions inthe of out discrepancies Haeckel’s between insizeand scale drawings and photo- world. When photography more became widely some used, scientists pointed years, Haeckel’s drawings commonly appeared throughout intextbooks the criticism from disputed who those evolutionary theory. Despite for this, many adapted from vertebrate anatomy of time, the immediately experts drew and wastion stated theory as “ontogeny recapitulates phylogeny.” evolution for each of organisms. those This known became as recapitula- the stagesthe of development found invertebrate stages the embryos reflected of rtebrate ancestor? ancestor? rtebrate Human (28days) Wit His b notochord

4.4 h today’s technology, scientists have shown that vertebrates all have a What aspects of Ernst Haeckel’s book led to criticism by his peers? by his to criticism led Haeckel’s book Ernst of aspects What How would these similar structures provide evidence of a common acommon of evidence provide structures similar these How would ook andook its accompanying drawings, which were borrowed and

Devel pharyngeal arches opmental Homologies 7a tail P genes, are inmore discussed in detail ig (30 da ig (30 ys) notochord arches pharyngeal tail Chicken days) (2.5 3F notochord tail Chapter 10:Principles of Evolution arches pharyngeal

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Anatomy Some of Darwin’s best evidence came from comparing the body parts of different species. Chief among such evidence were homologous structures. Homologous structures (huh-MAHL-uh-guhs) are features that are similar in structure but appear in different organisms and have different functions. Their appearance across different species offers strong evidence for common Web descent. It would be unlikely for many species to have such similar anatomy if HMDScience.com each species evolved independently. GO ONLINE The most common examples of homologous structures are the forelimbs of Dinosaur Descendants tetrapod vertebrates. The forelimbs of humans, bats, and moles are compared in FIGURE 4.5. In all of these animals, and indeed in every tetrapod, the fore- limbs have several bones that are very similar to each other despite their different functions. Notice also how the same bones vary in different animals. In addition to this, all tetrapods, including birds, will have five digits on their limbs at some point in their development. Homologous structures are differ- ent in detail but similar in structure and relation to each other. READING TOOLBox In using homologous structures as evidence of evolution, Darwin posed a logical question: If each of these groups descended from a different ancestor, VOCABULARY why would they share these homologous structures? A simple answer is that A tetrapod is a four-limbed animal. Tetra- means “four,” they share a common ancestor. and -pod means “foot.” The idea of common descent provides a logical explanation for how homologous structures appeared in diverse groups. Having similar structures doesn’t always mean two species are closely related, however. Some structures found in different species have the same functions but did not evolve from a common ancestor.

FIGURE 4.5 Homologous Structures Homologous structures, though they often have differing functions, are the result of a common ancestor.

Human hand Bat wing Mole foot

Notice that each of these homologous structures uses the same bones in relation to the others.

Apply What body part of a dolphin is homologous to the structures shown above? 7a (bl) ©Photo Researchers, Inc.; (bc) ©Dietmar Nill/Nature Picture Library; (br) ©D. Roberts/Photo Researchers, Inc. Roberts/Photo Researchers, Inc.; (bc) ©Dietmar Nill/Nature Picture Library; (br) ©D. (bl) ©Photo Researchers,

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(tr) ©Dietmar Nill/Nature Picture Library; (br) ©Gusto/Photo Researchers, Inc. group of structures provides evidence for a common ancestor. Explain. ancestor. Explain. acommon for evidence provides structures of group Analyze QUICKLAB evolved similar adaptations to overcome challenges. those rately. Their ancestors similar environmental faced challenges and similar of function wings inbats evolved and insects flying sepa- by of aseries long veins with cross-connections for strength. The wings do notinsect have bones, only membranes that are supported ture as an elongated hand, connected by skin.In thin contrast, ture. Bat wings, examined when closely, have same the bone struc- analogous structures did not derive from same the struc- original similar inorigin. This means that ineach of organisms, the the that perform asimilar flight—but case, this function—in are not F of bats and are analogous insects called structures, as shown in similar. Insects are bats arthropods, while are mammals. The wings Clearly organisms these insects. differinmore ways are than they about Think parts. body wings the of bats and wings the of flying ability to fly. can develop Both similar adaptations using different ro IGURE An Procedure Prob and predictions aboutit. “evidence” aboutapicture inorder to make observations, inferences, of what they are Inthisactivity, studying. you receive will pieces of Evolutionary biologists andpaleontologists rarely get all ofthepieces P ne 2. 2. 3. 1. 1. nment. For example, two different organisms from benefit the p iecing w information isobtained? w information Suppose two organisms have similar caused needs by envi- the evolutionary past? find that would allow themto see the bigpicture ofaspecies’ evidence from your teacher? Analyze strip of“evidence” that you receive from your teacher. Record ob evidenceas supporting for your prediction. Make apredic make aboutthispicture. provided, write down all observations andinferences that you can Using thethree strips tha aly 7a ro

4.6. vide Examples lem Using the terms homologous terms the Using z e

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n What ty ences didyou modifyasyou gathered more clu Inferr t your teacher has de pe ofevidence might paleontologists (uh-NAL-uh-guhs) are structures i ng and

analogous, 7a picture cutinto strips M a identify which identify t erials ferent structures. wings andinsect wings are derived from dif- are not evidence ofacommon ancestor. Bat Analogous structures evolved separately and 4.6 Figure

a n alogous Chapter 10:Principles of Evolution

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F such asthewings ofano no current use. ancestral form andhave or little greatly reduced from theoriginal are organs orstructures that are IGURE 10.4 Unit 4:Evolution 2. 1. R

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of evolution? considered critical evidence Why are common ancestry. which Darwinbased hisideas on evidenc Describe thefour sources of 4.7

Vestigial structures, Formative Assessment e for evolution upon n vestigial structures g

strich, M ai 7a n I 3F, 7a deas of aspecies. are clues to patterns history Structural the common ancestry? Summarize

Vestigial don’t Underdeveloped walk. or unused features are structures. vestigial called snakes have tiny pelvicbones and stumplike limbs, even though snakes tion, or at least are no longer for used For purpose. original their example, Some organisms have structures or organs that to lack any seem func- useful evolution works. evolution structuresvestigial among most the important examples demonstrating how took many generations for organs those to Today, shrink. biologists consider not appendix the retains any not is function still certain. not eat much and cellulose appendix the cannot digest cellulose. Whether or mammals. It helps to digest inplants. cellulose the As omnivores, humans do is aremnant amajor of cecum, the of part large the intestine inplant appendixthe is often cited as an example of structure. avestigial The appendix Thus, genes the for coding large wings were not over preserved generations. or by kicking viciously, large their wings would no longer have useful. been enough tobeen avoid predators. If ancient ostriches could escape by running generations, increasingly their large and long powerful bodies legs may have

in many snakes are homologous to pelvicbones the of tetrapods. with tetrapods such as lizards and dogs. The tiny pelvic bones and hind limbs adifferentserve As function. vertebrates, snakes share acommon ancestor found inan early ancestor that or function no may longer auseful now serve Ostriches wings use for but balance not to fly, as shown in MAI Ves Exam The w N ID tigial structures did nottigial get inone smaller individual organism. It 4. 3. C

ples of structures vestigial are found inmany organisms. In humans, structures EA ings of ostriches are another example of structures. vestigial

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Wha analogous structure? homologous structure andan be considered both a Apply Evaluate honeycreeper species? explain thedivergence ofHawaiian biogeographic evidence used to t

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BIOLOGY Natural Selection See Evolution by Natural Finch Beak Data a population evolve— Selection Find out how beak depth in or not. Discover how a species of Darwin’s finches See how disease-causing bacteria can populations can evolve, differs between islands evolve resistance to antibiotics. and how each principle of with different levels of natural selection is competition. important to the process.

online biology 305 HMDScience.com CorrectionKey=B DO NOT EDIT--Changes mustbemadethrough “File info” 306

F means “thestudyof.” means “ancient,” and-ology prehistoric life forms. Paleo- Paleontology isthestudyof VOCABULARY paleontology VOCABULARY groups inthefossil record stasis, andsequential nature of any data ofsuddenappearance, scientific explanations concerning 7B analyze andevaluate the molecular, anddevelopmental and homologies, includinganatomical, fossil record, biogeography, and among groups isprovided by the how evidence ofcommon ancestry was f tics ofboth land andmarine animals. yearsabout 40million ago and hascharacteris- igure Unit 4:Evolution READI ound in a desert in Egypt in2005.It livedound inadesert inEgypt 7Aanalyze andevaluate 5.1 10.5

N This skeleton ofBasilosaurus isis G TOOLB 7A, 7B o Evolutionary Biology Today x of evolution. Fossils provide arecord ofevolution. They have shown how hereditary variation occurs. molecular have biology added strong to support Darwin’s theoryofnatural selection. dreamed aboutinthe1800s.Inparticular, therelatively new fields ofgenetics and greatly. Scientistscan now share information andexamine evidence that was only of science before publishinghisresults. Since that time,technology hasadvanced Darwin had spentmanyyears collecting evidence ofevolution from different fields Connect to Your World K ey

because mostbecause living things do not form into fossils afterdie, and they because hypotheses about how evolution The fossil occurs. record is not complete, organisms, continues to provide information new and support current P MAI MAI aleontology C

o Evolution unites all fields ofbiology. Molecular andgenetic evidence fossil support andanatomical evidence. Fossils provide arecord ofevolution. N n N ID ce IDEAS p EA t n

(pay ew technology ourunderstanding isfurthering transitional fossils? Infer FIGURE 5.1. of transitional evolution inthe species of is shown whales in tell where one group ends and another One example begins. mix of traits intransitional often species makes to it difficult groups.between traits within groups as well as common the ancestors theory. “missing These links” demonstrate evolution the of changethe informs over outlined that time inhis Darwin record today includes many thousands of that species show ered, inlarge filling gaps fossil inthe record. The fossil many transitional forms have species between discov- been tween groups of organisms. Since Darwin’s time, however, worried about lack the Darwin of transitional fossils be- found.ever been However, no fossil that evidence contradicts evolution has fossils have not looked for been inmany areas of world. the had limbs the of land animals. -lee-ahn-TAHL-uh-jee), study the of fossils or extinct 7A, 7B 7A, Alt In Da

Why are fossils such as Basilosaurus as isis such fossils Why are hough scientists organisms classify into groups, the rwin’s time, science. paleontology anew was still Basilosaurus isis 7B had awhalelikebody, but it still con sidered sidered

©Philip D. Gingerich/University of Michigan CorrectionKey=B DO NOT EDIT--Changes mustbemadethrough “File info”

©Douglas P. Wilson/Frank Lane Picture Agency/Corbis and anatomical evidence. anatomical and fossil evidence genetic and support Molecular be Explain

structure of an ancient marine worm, as shown in ancestor. For example, proteins the of light-sensitive brainlike cells inthe different that species have same the proteins most likely come from a common sequences and for look homologous sequences indifferent from Cells species. liver or muscle cells. Computers are to search used databases of protein printing. Aunique of set proteins are of found types cells, such as inspecific byrevealed comparing proteins, their atechnique molecular finger- called Protein comparisons pseudogenes,between however, must acommon reflect ancestor. similar lifestyles, such as awolf and acoyote, due to natural Similarities selection. evolutionary relationships. Functioning genes may similar inorganisms be with arethey on passed through generations, provide they so another way to figure out butfunction are along carried withDNA. functional still change can They also as ofevidence evolution. Pseudogenes are like structures. vestigial no They longer Pseudogenes DNA sequences with past geologicalevents. organisms.the Scientists hope to eventually able be to correlate changes in sequences of DNA in organisms can show evolutionary relationships among tions, sequences the of nucleotides change over time. Thus, comparing the remarkable number of proteins that are similar to one another. to Due muta- 20 amino acids, it possible has to been determine that organisms share a huge amount of information on evolutionary history. there are Because be. thousands of genes inmost organisms, DNA contains a thatfact more the related two organisms are, more the similar DNA their will change over due time to mutations. DNA sequence analysis dependson the DNA sequence analysis evolutionary relationships species. between acids. DNA or protein sequence comparisons to show used can be probable genetic and code make most of same the proteins from same the 20amino genetic mechanisms. living all things have Because DNA, share they same the As with homologous different traits, very have species similar molecular and clusters are found inorganisms that lived as far back as 600million years ago. indicate distantalso avery common ancestor. Evidence of homeobox gene quences of genes are found inmany organisms, to from humans. flies fruit They homeobox genes control development the structures.- of se These specific Homeobox genes cells of vertebrate the eyeoriginally came from brain. cells inthe shows ashared worms between and ancestry vertebrates. It shows also that the closely resemble of those cells found vertebrate inthe eye. This resemblance MAI tween organisms? Bec N

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The eye spots ofthis N G TOOLB o x

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FIGURE 5.3 Evidence of Whale Evolution The evidence that whales descended from hoofed mammals is supported by scientific research in several different fields of biology.

Vestigial Evidence Modern­-day whale Many modern whale species have vestigial pelvic and leg bones. They also have vestigial Fossil Evidence nerves for the sense of There are many transitional fossils that have characteristics of both land mammals smell, and small mus- and whales. These are a few examples. cles devoted to exter- nal ears that no longer Dorudon about 40 million years ago exist.

Embryological Evidence Whale embryos have features such as hind leg buds and nostrils that resemble those of land animals. Nostrils are at the Tiny hind legs were useless on land, and a shorter neck and longer tail makes end of the whale’s Dorudon similar to modern-day whales. Its ankle joints closely resemble snout early in those of modern ungulates. development but travel to the top of the head to form one Ambulocetus natans about 50 million years ago or more blowholes before birth.

nostril

hind leg bud With a name that means “the walking whale that swims,” Ambulocetus natans was an amphibious fish eater the size of a sea lion. Molecular Evidence Pakicetus about 50 million years ago The DNA sequences of milk protein genes in whales and hoofed mammals are very similar, as demonstrated by the DNA fragments below.

Hippopotamus TCC TGGCA GTCCA GTGGT

Humpback whale CCC TGGCA GTGCA GTGCT Pakicetus had a whale-shaped skull and teeth adapted for hunting fish. However, with ear bones that are in between those of land and aquatic mammals, it could not hear well underwater or make deep dives.

CRITICAL Whales are divided into two groups: toothed whales, such as the orca pictured above, and baleen VIEWING whales, such as the humpback whale pictured on the next page. Which would you predict is most closely related to Dorudon? Explain. (tr) ©Will Darnell/Animals Animals - Earth Scenes (tr) ©Will Darnell/Animals

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©Paul A. Souders/Corbis Evolution all ofbiology. unites fields Explain. ev Evaluate 10.5 3. 2. 1. R

light of evolution.” (1900–1975) once noted, “Nothing makes inbiology except sense inthe ered about life As on great the Earth. geneticist Theodosius Dobzhansky managebest endangered There species. much is so more waiting discov- to be helps biologists understand come where diseases from, new as well as how to geology, geography, chemistry, and ecology. of The idea common descent potamus is closest the living land animal related to whales. relationship this confirm and even provide that evidence hippo- the examples from fossil the record shown in ancestors of were whales hoofed land mammals. Comparing the For example, you have read that fossil suggests evidence that early of has technology use the supported modern cases, fossil evidence. light on mechanisms the and patterns of evolution. In some gathered through alone molecular evidence is overwhelming. number of proteins in asingle organism, amount the of data providingmore data than ever before. Considering the 21st centuryis an exciting to time study evolutionary biology. New tools are Scientists are actively still studying evolution through natural The selection. antelope, and hippopotamuses. and antelope, ancestor with group the of hoofed mammals that includes deer, provide for evidence descent the from of whales modern acommon in skull shape, limb structures, modified and changes length intail transitional characteristics land between mammals and Shifts whales. idence for common ancestry among groups such as land mammals and whales? MAI

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CHAPTER 10 TOOLBOXREADING

R “Natural selection dependsonheritable variations.” variation andnatural, you selection could write the terms are connected. For example, for theterms below, write asentence ortwo to clearly explain how each other invarious ways. For each group ofwords The voc V R 10.1 Chapter vo 10. 8. 6. 4. 2. 5. 1. 9. ocabulary Connections 3. 7. eviewing eviewing

finches? organisms such astheGalápagos tortoises and What insightsdidDarwin gain fr Darwin’s ideas abouthow evolution works. Briefly e meaning relates to vestigial structures. which means “track orfootprint”. Explain how this The term v of natural selection. propo Describe oneidea aboutevolution that was meaning relates to homologous structures. homos The term homologous comes from theGreek word fos vestigia adapt population, v cat

foss species evolution uniformitarianism gradualism catastrophism astrophism, gradualism sil, paleontology abulary terms inthischapter are related to ation, evolution sed before Darwinpublishedhistheory il Review , whichmeans “thesame”. Explain how this l structure, analogous structure xplain how thegeologist Charles Lyell influenced

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20. 18. 16. 14. 12. 15. 19. 13. 17. 11. Review Games•ConceptMapSectionSelf-Checks Go online

extended thisidea inhistheoryofnatural selection. limits to humanpopulation growth. Explain how Darwin resources suchasfood, water, andshelter are natural Thomas Malthus was anec observations provide evidence that isvery Earth old? organisms highupinthemountains. How didthese that r On hisvoyage, Darwinfound fossils ofextinctorganisms except inthelightofevolution.” Dobzhansky means: “No Explain what thefollowing quote by Theodosius among species? structures whendetermining evolutionary relationships How are g biology. Explain how thisfield to isimportant evolutionary Pal vestigi Give anexample ofavestigial structure andexplain how evaluate oneexample ofsuchembryological evidence. dev Embryology provides evidence ofevolution by revealing with modification”. in rock str Explain how thesequential nature offossil groups found to occur. these principles isnecessary for natural selection with modification. Briefly explain how each of vari Natural selection isbased onfour mainprinciples: artificial selection? impor Why isheritability eontology isthestudyoffossils orextinct organisms. ation, overproduction, adaptation, anddescent elopmental homologies amongspecies.Analyze and esembled livingorganisms ofmarine andshells HMDScience.com Interact al structures are significant to evolution. 7a 7d ata Darwin’s supports principle of“descent enes andproteins similar to homologous 10.5 10.4

7d, 7e vestigial structure analogous structure homolog biogeography paleontology i ve Review 7a thing in biology makesthing inbiology sense tant for both natural and ous structure 7d 7B onomist whoproposed that Chapter 10:Principles of Evolution

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Critical Thinking 21. Compare Jean-Baptiste Lamarck hypothesized that Analyzing Data Interpret Line Graphs changes in an environment led to an organism’s greater One hundred million seabirds use the island of Gaugh, or lesser use of a body part. Although his hypothesis in the South Atlantic Ocean, as a critical nesting ground. was incomplete, what ideas related to evolution did Non-native carnivorous mice eat the helpless seabird 3F Lamarck and Charles Darwin share? chicks at a rate of about 1 million per year. Prior to the 22. Evaluate What types of scientific evidence provide arrival of the mice, no natural predators existed on the support for common ancestry among groups such as island, so the birds did not evolve any defense mecha- land mammals and whales? How would you assess nisms. Scientists estimate the current population of the the relative strength of these different types of mice at 700,000. The graph below displays a projection ­evidence? 7A of seabird casualties and changes in the size of the mouse population. 23. Analyze The turkey vulture and the California condor both feed upon dead animals, known as carrion. Neither seabird casualties and Mouse population species of bird has feathers on its head. Explain how 6 natural selection may have played a role in the feather- Seabird casualties less heads of these carrion eaters. 7e 5 Mouse population

24. Analyze What are three trends that biologists have 4 identified in the transitional characteristics of different groups in the whale fossil record? 7b 3 Interpreting Visuals 2 Use the following diagram, which shows the evolution 1 of the wild mustard plant, to answer the next three questions. (millions) Number of individuals 0 1 5 10 15 20 Years

cabbage 28. Interpret What does the graph show about seabird casualties and the mouse population over a 20-year period? cauliflower broccoli 29. Predict Imagine that some seabirds began defending their nests from the mice, and that this behavior is heritable. What changes might such a graph show over wild mustard the next 20 years? Explain. 25. Infer Traits of the wild mustard plant have been emphasized by artificial selection to produce different vegetables. In some varieties, the flower heads were Making Connections emphasized. In other vegetables, it was the leaves or the 30. Write a Scenario Imagine a way in which seabirds could stems that were to be eaten. Which traits were empha- adapt to the mouse population and avoid predation of sized to produce cauliflower? Cabbage? their chicks. Then consider how, after many generations, the mouse population could counter this defense and 26. Apply Describe a procedure humans may have used to again limit the seabird population. What are possible produce broccoli, which has small flowers and thick adaptations that could lead to this co-evolution of mice stems. and seabirds? 7e 27. Predict What would a protein comparison of broccoli, 31. Synthesize Look again at the picture of the star-nosed cabbage, and cauliflower confirm about their relation- mole. Its claws are well adapted for breaking through ships to each other? 7a soil. How could natural selection have played a role in this trait becoming common among star-nosed moles? 7c, 7e

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Biology End-of-Course Exam Practice

Record your answers on a separate piece of paper. 2G, 7B MULTIPLE CHOICE 4 The diagram below represents several sedi- mentary rock layers in which fossils of different 7A organisms have been found. The rock layers show 1 As developing embryos, some organisms appear no evidence of having been disturbed since their to have features that are similar in structure. As formation. these organisms continue their development, A features that were similar in the embryonic stage B develop into different structures that have C different functions. What type of evidence of D common ancestry do these features represent? A vestigial structures E B homologous structures What information about the ages of the fossils C analogous structures relative to each other can be explained by their D fossil structures positions in these rock layers? A The rock layers do not provide any 7a information about the ages of the fossils 2 Although the fossil record is incomplete, relative to each other. paleontologists continue to search for fossils that are commonly referred to as “missing links.” B The rock layers suggest that the fossils in layer What evidence of evolution do discoveries of A are much older than those in layers B, C, D, fossil evidence known as “missing links” provide and E. to scientists? C The rock layers suggest that the oldest fossils A Discoveries of “missing links” provide fossil are in layer E and the youngest are in layer A. evidence that contradicts the theory of D The rock layers suggest that all of the fossils evolution. found in the rocks will be of the same age B Discoveries of “missing links” show that regardless of the type of organism the fossil organisms once thought to be related are not. represents. C Discoveries of “missing links” serve as transitional species that show the evolution 7C, 7D within and between related groups. 5 An herbicide killed 99% of a weed population. D Discoveries of “missing links” serve as Which of the following is the best biological additional evidence that organisms do not explanation for some weeds being able to survive? change or evolve. A Some individuals were able to evolve before the spraying. 7C, 7D B The spray caused some individuals to mutate, 3 All vertebrates have very similar Hox genes. How and they were able to survive and reproduce. does this provide evidence suggesting vertebrates BI_CTXESE026100_48A.ai C Each individual occupied a different ecological evolved from a commonSam Valentino ancestor? niche and so some were unaffected. A Greater similarity of genes indicates closer 10.31.12 D Genetic variation in the population allowed evolutionary relationships2nd pass among species. some weeds to survive. B Species with major differences in Hox genes would have gone extinct. THINK THROUGH THE QUESTION C The greater the number of Hox genes present, Consider what conditions must be present for the greater the relationship among species. ­natural selection to occur. D Hox genes control the same genes in all species of vertebrates.

Chapter 10: Principles of Evolution 313