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Evolution© Jones &and Bartlett Learning, Extinction LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Chapter© Jones Themes & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION How did early theories of evolution differ from Darwin’s? What sorts of evidence led Darwin to his theory of evolution? How is genetic information stored and transmitted from parents to offspring? © Jones & WhatBartlett produces Learning, genetic LLC variation? © Jones & Bartlett Learning, LLC NOT FOR SALEWhat is OR the DISTRIBUTIONevidence for natural selection? NOT FOR SALE OR DISTRIBUTION How do new species and other groups originate? What is the evidence for evolution? How does extinction affect evolution? © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Chapter Outline © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 4.1NOT Introduction FOR SALE OR DISTRIBUTION 4.9 EvolutionNOT and FOR the Fossil SALE Record OR DISTRIBUTION 4.9.1 Comparative anatomy 4.2 Early Theories of Evolution 4.9.2 Cladistics BOX 4.1 Evolution of Biologic Classification 4.9.3 Microevolution and the Species Concept © Jones & Bartlett Learning, LLC © Jones4.9.4 & Bartlett Macroevolution Learning, LLC NOT FOR SALECharles OR DISTRIBUTION Darwin and the Beginnings of NOT FOR SALE OR DISTRIBUTION 4.3 Mass Extinction the Modern Theory of Evolution 4.10 BOX 4.2 Charles Darwin, the Person 4.11 Biodiversity Through the Phanerozoic Basic Premises of Darwinian Evolution 4.4 © Jones & Bartlett Learning, 4.12 LLC Summary © Jones & Bartlett Learning, LLC BOX 4.3 Misuse of Darwin’s Theory NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 4.5 Inheritance and Variation 4.6 Genetic Code and Mutation 4.7© JonesEvidence & for Bartlett Natural Learning,Selection LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 4.8 Speciation

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. developed and modified, leading to new questions. As © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Introduction we will see, several of these questions stem from a better NOT FOR SALE4.1 OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Charles Darwin (1809–1882) is rightfully understanding of the fossil record: How do new species credited with founding the modern theory of evolu- arise? How do new anatomic structures like wings or tion because the basic foundation of the theory laid eyes and wholly new groups of organisms—like reptiles down by him has remained largely intact to the present. or mammals—arise? How do mass extinctions of the © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Darwin’s theory supported, and was supported by, the biosphere—well documented in the fossil record— notion of deep timeNOT implicated FOR SALE by Hutton OR DISTRIBUTIONand Lyell create new evolutionary NOTopportunities? FOR SALE OR DISTRIBUTION (see Chapter 1). Recall from Chapter 1, however, that the view of Earth espoused by Lyell was one of strict Early Theories of Evolution equilibrium: no net change. But with Darwin’s theory 4.2 Two of Darwin’s predecessors, both French, came© Jones the growing & Bartlett realization Learning, that not LLC only has life stand out© for Jones their views & onBartlett evolution: Learning, Jean Baptiste LLC Pierre evolvedNOT FOR but so SALE too have OR Earth’s DISTRIBUTION physical systems. Natu- Antoine deNOT Monet, FOR Chevalier SALE de Lamarck,OR DISTRIBUTION or just Lamarck ral systems can exhibit directionality or secular change, (1744–1829), and Baron Georges Cuvier (1762–1839) because they are open systems, that is, they can evolve. (Figure 4.1). Lamarck originally believed that certain Darwin’s theory is therefore not only fundamental to groups of organisms—now called species—were fixed © Jones & Bartlettthe study Learning, of the history LLC and evolution of life but also© Jonesand & did Bartlett not evolve, Learning, but began toLLC change his views as his NOT FOR SALEstrengthened OR DISTRIBUTION the inkling that physical systems—andNOT FORstudies SALE progressed OR DISTRIBUTION(Box 4.1). Lamarck based his theory thus Earth—can evolve as well. of evolution on spontaneous generation which stated that Like so many theories, however, Darwin’s was living matter arises from nonliving matter. Lamarck based preceded by others. To fully comprehend the signifi- his acceptance of spontaneous generation on his observa- cance of the modern theory of evolution, we must ex- tion that the simplest organisms had no obvious organs, amine these earlier© theories. Jones In & doing Bartlett so we Learning,get another LLCso Lamarck reasoned they© must Jones have & evolved Bartlett directly Learning, LLC glimpse as to howNOT scientists FOR think SALE and how OR theories DISTRIBUTION are from nonliving substances.NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett(a) Learning, LLC © Jones(b) & Bartlett Learning, LLC NOT FOR SALEFigure OR 4.1 DISTRIBUTION(a) Jean Baptiste Pierre Antoine de Monet, ChevalierNOT de FOR Lamarck SALE (1744–1829). OR DISTRIBUTION (b) Baron Georges Cuvier (1762–1839).

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALEBOX OR4.1 DISTRIBUTION evolution of Biologic Classification and the Species Concept

A species is a group© of Jones organisms & thatBartlett interbreed Learning, with menclature,LLC and any species described© Jones before & thisBartlett time Learning, LLC one another and produceNOT fertileFOR offspring. SALE TORhe point DISTRIBUTION of are considered invalid. However,NOT species FOR originally SALE de -OR DISTRIBUTION reproduction is to propagate the species. Species are usu- scribed after 1758 may still be redescribed or placed ally recognized by physical features thought to reflect the in new groupings based on new data. identity of the species, such as anatomic traits, distinctive As evolutionary theory began to take hold, Linnaeus’ coloration, or behavior. Many species have “common” system of biologic classification began to take on a new names© Jones used by & lay Bartlett people. However, Learning, these terms LLC can be meaning: evolutionary© Jones relationships. & Bartlett A classification Learning, rec -LLC confusing,NOT FOR especially SALE if they OR are DISTRIBUTIONused to refer to different ognizes similaritiesNOT or FOR dissimilarities SALE between OR DISTRIBUTION objects, in species. To avoid confusion among scientists, each spe- this case species. The purpose of a biologic classification cies is given a scientific name consisting of two names: is to show evolutionary relationships, or phylogeny, the genus and the species. For example, the scientific between different groups of organisms, or taxa (taxon, singular). Biologic classification and phylogenetic rela- © Jones & Bartlettname of human Learning, beings is LLC Homo sapiens. Homo is the © Jones & Bartlett Learning, LLC tionships are hierarchies. These hierarchies consist of genus and sapiens is the species. The scientific name for NOT FOR SALE OR DISTRIBUTION NOTdifferent FOR levels,SALE or ORcategories—kingdom, DISTRIBUTION phylum, class, humans means “prescient man,” referring to the mental order, family, genus, and species—each of which may ability of humans to foresee into the future and anticipate be further subdivided or lumped together. The actual the consequences of their actions and those of nature. groups, or taxa (such as particular species), are placed By international convention the scientific name is always into higher taxa corresponding to the different categories; underlined or set off ©from Jones the surrounding & Bartlett text inLearning, some LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONthus, each taxon shares characteristicsNOT FOR with theSALE other OR DISTRIBUTION other manner, and the genus name is always capital- members of the same taxon. The science of biologic ized, whereas the species name is not (species is used classification is calledtaxonomy . A biologic classifica- for both the singular and plural; there is no such word tion is therefore like a series of boxes nested within as “specie”). Each genus is represented by one or more progressively larger boxes. In biologic classification these species.© Jones Thus, when& Bartlett referring Learning,to a particular speciesLLC one boxes are called© categoriesJones &with Bartlett the categories Learning, becoming LLC citesNOT both FOR names—genus SALE ORand species—not DISTRIBUTION just the spe- more and moreNOT inclusive. FOR T axaSALE and categories OR DISTRIBUTION may also cies name by itself, because there could well be another be subdivided (for example, subclasses) or lumped to- completely different genus represented by a species with gether (for example, superfamilies). For example, Homo the same species name. sapiens is classified as follows: The first naturalist to systemically catalog and de- CATEGORY: TAXON © Jones & Bartlettscribe animals Learning, and plants LLC was the Swedish botanist, © Jones & Bartlett Learning, LLC Kingdom: Animalia NOT FOR SALECarolus OR Linnaeus DISTRIBUTION (1707–1778), who held that spe- NOT FOR SALE OR DISTRIBUTION Phylum: Chordata (animals with some form of cies were fixed. He eventually described about 4200 backbone) species of animals and 7700 species of plants. There Class: Mammalia (mammals, which are are now about 1.4 million described species, which warm-blooded, possess hair, and produce may represent only about one-tenth of all modern © Jones & Bartlett Learning, LLC milk for their young) © Jones & Bartlett Learning, LLC species. Many species have common names, but the NOT FOR SALE OR DISTRIBUTION Order: Primates (monkeys,NOT FOR apes, humans)SALE OR DISTRIBUTION same common name may be used in different areas Superfamily: Hominoidea for different species. To avoid confusion Linnaeus gave Family: Hominidae each species a Latinized description. However, use of Genus: Homo the description was quite clumsy, and he decided to Species: sapiens give© eachJones species & Bartlett a “nickname.” Learning, This led to LLC the estab- © Jones & Bartlett Learning, LLC lishmentNOT FORof binomial SALE nomenclature OR DISTRIBUTION in which each Besides the KingdomNOT FOR Animalia, SALE several OR other DISTRIBUTION kingdoms species is recognized by two names, as described are recognized: Plantae, Fungi (mushrooms, etc., includ- above. Linnaeus’ system is still used today. In fact, his ing microscopic fungi), Protista (single-celled plants and monumental work, Systema Naturae, first published animals), and two kingdoms of bacteria, the Archaea © Jones & Bartlettin 1758, is Learning,taken as the startingLLC point of binomial no- © Jonesand the &Eubacteria. Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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The modern© viewJones of biologic & Bartlett classification Learning, and LLCseparated species. On the© other Jones hand, & Cuvier Bartlett had aLearning, LLC the concept of speciesNOT FOR have themselves SALE OR evolved. DISTRIBUTION Bio very narrow notion of a species,NOT inFOR which SALE a particular OR DISTRIBUTION logists recognize that within a species there is typi- specimen was supposed to represent all members of cally a broad range of variation in physical features. that species; this kind of thinking originated with the Sometimes this range can be quite broad, such as Greek philosopher Plato, who viewed all living things that found among different breeds of dogs. Despite as having an “ideal type.” ©their Jones tremendous & Bartlett differences Learning, in size andLLC coloration, Darwin© alsoJones wrestled & Bartlett with this problem Learning, and eventu LLC- NOTdifferent FOR breeds SALE of dogs OR are DISTRIBUTION thought to be descended ally recognizedNOT that FOR each SALE species OR can varyDISTRIBUTION within broad from an ancestral wolf lineage. This lineage alone limits. In other words most specimens resemble the contained the DNA from which all different purebred “average” appearance of the species, but many speci- lines of dogs have been bred. Obviously, this range mens deviated from the species’ average, sometimes © Jones & Bartlettof variation Learning, in physical LLC traits can sometimes make© it Jonesquite & strongly.Bartlett Nevertheless, Learning, the LLC existence of species NOT FOR SALEdifficult OR DISTRIBUTIONto decide if one is studying separate speciesNOT or FORwas actuallySALE used OR asDISTRIBUTION an argument against Darwinian variation within the same species. This was the basic and earlier theories of evolution. The reasoning was that problem confronted by early evolutionary biologists because species are not observed to change into new who began to describe different types of organisms. species, species do not evolve. Even though Darwin Lamarck saw the possibility for almost endless varia- used the results of animal breeding experiments to tion and the continued© Jones production & Bartlett of new Learning,forms from LLCsupport the process of natural© Jones selection, & newBartlett species Learning, LLC nonliving matter;NOT nature FOR was SALE just too OR “fluid” DISTRIBUTION in his were never produced. SomeNOT of Darwin’s FOR SALE critics usedOR DISTRIBUTION view to have such distinct biologic boundaries that this evidence against his theory, as well.

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORLamarck SALE also OR believed DISTRIBUTION in the concept of a “striving”NOT in response FOR SALE to new OR environmental DISTRIBUTION condi- “Chain of Being” which stated that all organisms could tions; organisms evolved new structures according to be arranged in a continuous hierarchy stretching from their “need” through use and disuse. This theory of the simplest organisms all the way to humans at the top the inheritance of acquired characteristics asserted, (Figure 4.2). The origins of the Chain of Being concept for example, that the short-necked ancestors of mod- © Jones & Bartlettcan be traced Learning, all the way LLC back to Aristotle. According© Jones ern & giraffes Bartlett had Learning,lengthened theirLLC necks as members NOT FOR SALEto this OR view, DISTRIBUTION because only the simplest animals couldNOT FORof each SALE generation OR DISTRIBUTION strove to reach the foliage higher evolve from nonliving matter, more complex species in trees; the slightly longer neck of each generation must be descended from simpler ones in a progressive was passed to the next during reproduction. In other manner. Thus, in Lamarck’s view new, simple creatures words evolution was teleological, meaning it was goal- evolved through separate© Jones acts of & spontaneous Bartlett Learning, generation LLCoriented or purposeful, ©a viewJones held & by Bartlett many other Learning, LLC and then moved upNOT the ChainFOR ofSALE Being alongOR DISTRIBUTION a kind of naturalists before and afterNOT Lamarck. FOR SALEBut the ORtheory DISTRIBUTION evolutionary “escalator.” The dead residues fell back of the inheritance of acquired characteristics begged to the base of the escalator to be used again, in a cyclic the question as to how the characteristics are passed manner, in the evolutionary process. A particular group’s on to offspring. Consequently, Lamarck’s theory was complexity was therefore a measure of its age: the more never widely accepted, and some scientists dismissed © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC primitive a group, the more recently it had evolved. Be- him as a crank. causeNOT the FOR Chain SALE of Being OR emphasized DISTRIBUTION that evolution was NOTOne such FOR scientist SALE was OR Georges DISTRIBUTION Cuvier. Cuvier progressive, it also emphasized that evolution progressed developed a classification scheme based on his studies toward more perfect forms, namely humans. of comparative anatomy for which he was renowned Finally, Lamarck believed that organisms (Box 4.1). By observing a single bone or tooth Cuvier © Jones & Bartlettwere capable Learning, of evolving LLC the organs they needed and© Jones could & Bartlettpredict the Learning, rest of the animal’s LLC skeleton through NOT FOR SALEcould OR change DISTRIBUTION their characteristics through an internalNOT FORhis knowledge SALE OR of anatomicDISTRIBUTION relationships (what Cuvier

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Present Figure 4.2 the Chain of Being, as envisioned by Lamarck. Note how new groups of organisms (arrows) originating earlier reach a more advanced stage than those groups originating later. [Modified from: Bowler, P. 1989.Evolution: The History of an Idea. © Jones &Revised Bartlett ed. Berkeley: Learning, University LLC of California Press. Figure 10 (p.© 85).] Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION called the “correlation of parts”). Based on anatomic relationships Cuvier concluded that species and other Concept and Reasoning Checks taxa were so complex they could only be fixed and 1. Was Darwin the first person to recognize a unchangeable (Box 4.1).© Jones Instead & of Bartlett an escalator-like Learning, LLCtheory of evolution? © Jones & Bartlett Learning, LLC progression from simpleNOT to moreFOR complex SALE ORcreatures, DISTRIBUTION 2. Why were species originallyNOT thought FOR toSALE indicate OR DISTRIBUTION different groups of organisms were viewed as being a lack of evolution? separate branches in a tree-like arrangement. One branch was no more advanced than another; branches were ©merely Jones different & Bartlett because Learning, each was adapted LLC to a © Jones & Bartlett Learning, LLC differentNOT mode FOR of life.SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Through his studies of fossil forms, Cuvier Charles Darwin and the Beginnings also gradually realized a series of extinctions had 4.3 occurred. Because the changes between fossil assem- of the Modern Theory of Evolution blages were abrupt, he concluded a series of extinc- To fully appreciate the perspective and power © Jones tions& Bartlett had occurred Learning, caused LLC by movements of the land © Jonesof the evolutionary & Bartlett viewpoint, Learning, we need LLC to briefly exam- NOT FORand SALE sea. Cuvier OR DISTRIBUTION was therefore lumped into the cata- NOTine FOR how DarwinSALE arrivedOR DISTRIBUTION at his theory. Charles Darwin strophist camp by Lyell (see Chapter 1). However, (Figure 4.3) was the naturalist on the voyage of the contrary to what Lyell said, Cuvier did not explain H.M.S Beagle from 1831 to 1836. During the expedition the repopulation of Earth after an extinction as the Darwin visited the Canary Islands in the Atlantic Ocean, work of a Creator, and© heJones refused & toBartlett equate the Learning, last made LLC multiple short expeditions© Jones into the & interiorBartlett of Learning, LLC extinction with the biblicalNOT FOR Deluge. SALE Cuvier OR did DISTRIBUTION not South America from both the eastNOT and FOR west SALEcoasts, and OR DISTRIBUTION accept the evolution of species (or transmutation, explored the Galápagos Islands about 600 miles west as it was then called) after extinction but instead of South America and coral reefs of the South Pacific. suggested that populations repopulated Earth from Being the keen naturalist that he was, Darwin filled his refuges after extinction. notebooks with many observations during the trip and © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Despite Cuvier’s long-standing influence, sent crate after crate of specimens back to England. At however,NOT other FOR workers SALE sawOR tantalizingDISTRIBUTION patterns in least two fundamentalNOT FOR themes SALE run throughOR DISTRIBUTION his observa- the classification—or groupings—of different plants tions and still serve as foundations for the modern theory of and animals groups, and the concept of transmuta- evolution: the seemingly infinite variety and variation of tion started to make headway once again in the 1830s plants and animals in nature (Box 4.1) and their biogeo- © Jones (Box& Bartlett 4.1). This Learning, was basically LLC the state of evolutionary © Jonesgraphic &distribution Bartlett (see Learning, Chapter 2). LLC Why, Darwin asked NOT FORbiology SALE when OR CharlesDISTRIBUTION Darwin came onto the scene. NOThimself, FOR would SALE a Creator OR DISTRIBUTION produce so many different kinds

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(a) © Jones & Bartlett Learning, LLC(b) © Jones & Bartlett Learning, LLC Figure 4.3 CharlesNOT Darwin FOR (a) in SALE1849 at theOR age DISTRIBUTION of 40, ten years before publication of On theNOT Origin FORof Species SALE. (b) Darwin OR DISTRIBUTION in 1881, the year before his death.

of organisms, and why would the Creator distribute them of books (Box 4.2). From his observations Darwin in© different Jones places & Bartlett over the Learning, planet? LLC began to© develop Jones general & Bartlett hypotheses Learning, about nature. LLC As NOT FOROne ofSALE the most OR DISTRIBUTIONoften-cited examples of it turnedNOT out one FOR of the SALE most influential OR DISTRIBUTION works Darwin Darwin’s observations is “Darwin’s finches” Figure( 4.4). ever read was Charles Lyell’s Principles of Geology (see Different islands of the Galápagos, sometimes within Chapter 1). He received the first volume before leaving sight of one another, are inhabited by different species on the expedition of the Beagle and received the later of finches. The beaks of the finch populations were so two volumes during the trip, and Darwin and Lyell © Jones & Bartlettdifferent fromLearning, one another LLC that Darwin did not realize© Jones became & Bartlett close colleagues Learning, after LLCDarwin’s return. NOT FOR SALEhow closelyOR DISTRIBUTION related the species were. After study byNOT a FOR SALEAlthough OR DISTRIBUTIONDarwin had long intended to gather noted ornithologist in England upon Darwin’s return, his observations into a theory and a book, he procrasti- it became clear that the beaks reflected the adapta- nated, despite the warnings of Lyell and other colleagues tion and evolution of finch populations on different that someone else might “scoop” him. In science, as in islands into different species in response to different the rest of society, priority means a great deal in terms of food sources. For ©example, Jones finches & Bartlett with robust Learning, beaks LLCrecognition and prestige. In© fact,Jones Alfred & RusselBartlett Wallace Learning, LLC ate large seeds, whereasNOT othersFOR withSALE longer OR beaks DISTRIBUTION pried (Figure 4.5), another BritishNOT naturalist FOR SALE who had OR also DISTRIBUTION insects from underneath bark. Why should this be? developed a keen interest in beetles as a young man, Similarly, while visiting the Galápagos Darwin was contacted Darwin in 1858 about his own theory of informed by one of the inhabitants that one could tell evolution. Wallace had spent many years in the tropi- which© Jones island & he Bartlett or she was Learning, on simply by LLC looking at the cal rain ©forests Jones of the & Amazon Bartlett and Learning, southeast Asia LLC and tortoisesNOT FOR (refer SALE to this ORchapter’s DISTRIBUTION frontispiece). Like the had developedNOT FOR a theory SALE remarkably OR DISTRIBUTION similar to that of finches and tortoises, plants and other organisms also Darwin’s. Wallace reported that he first realized his varied from one island to the next. Darwin absorbed theory while suffering from one of numerous feverish this information, as well. bouts with malaria while working in Indonesia; the Upon his return to England, Darwin devoted idea occurred to him that individuals less resistant to © Jones & Bartlettthe rest ofLearning, his life to synthesizingLLC the observations© Jonesdisease, & Bartlett predation, Learning, and environmental LLC change would NOT FOR SALErecorded OR in DISTRIBUTION his notebooks from the voyage into a seriesNOT FORbe culled SALE from OR natural DISTRIBUTION populations.

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(a) (b)

(d) (e) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION (f) NOT FOR SALE OR DISTRIBUTION

(g) (h) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR TreeDISTRIBUTION (i) finches

(k)

Figure© Jones4.4 Darwin’s & Bartlett finches. [R eproducedLearning, from: LLC Lack, D. 1947. Darwin’s Finches:© AnJones Essay on& theBartlett General Learning,Biology Theory LLC of Evolution, 1st ed. Cambridge, UK: Cambridge University Press. Illustration by Lt. Col. William Percival Cosnahan Tenison.] NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Charles Darwin was the son of Robert Darwin, a promi- of the Anglican Church. There, Darwin met some of the nent physician, who encouraged Charles to follow in scientific luminaries of the day.T hese included the his footsteps by attending© Jones medical & school Bartlett at Edinburgh. Learning, famous LLC geologist Adam Sedgwick,© Jones who would & Bartlett even- Learning, LLC Charles attended theNOT school FOR but SALE was bored OR by DISTRIBUTION the tually introduce him to the fieldNOT of geology FOR inSALE Wales, OR DISTRIBUTION lectures and horrified by anatomy classes, and he and John Henslow, who taught mineralogy and botany eventually fled. Unfortunately for Robert Darwin, and who would recommend Darwin for the posi- Charles seemed to have had no other interests than tion of naturalist on the voyage of the H.M.S. Beagle. beetle-collecting© Jones & andBartlett hunting. Learning, Consequently LLC, his father Charles’s father© Jonesat first objected & Bartlett to the tripLearning, but eventu -LLC decided that Charles should become a minister, which ally relented when his uncle and future father-in-law, NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION in those days would have served as a respectable Josiah Wedgwood, intervened. occupation to allow Charles to continue with his natu- After his return to England, Darwin eventually ralistic pursuits. married his first cousin, Emma Wedgwood, and they So Charles next attended Cambridge University, settled briefly in London before moving to Downe, © Jones & Bartlettwhich was then,Learning, along with LLC Oxford University, a bastion © Joneslocated &west Bartlett of London, Learning, in 1842. LLCDarwin probably NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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wanted to spend© moreJones time & thinking Bartlett and Learning, writing and LLC Although he had been© in Jones good health & Bartlett as a young Learning, LLC less time on professionalNOT FOR activities SALE and OR the DISTRIBUTION hubbub man and during most of theNOT Beagle’ FORs voyage, SALE Darwin’s OR DISTRIBUTION of London, all of which seemed a distraction to him. health suffered through the years, and he frequently Emma and Charles settled into a comfortable exis- visited spas for so-called water cures. It is thought that tence at Downe, during which Charles spent much of Darwin may have contracted a parasitic disease while his time writing in his study, conducting experiments in South America. Also, given his religious background © orJones dissecting & Bartlett specimens, Learning, and taking LLC long walks in the implications© Jones of his & theory Bartlett of evolution Learning, must haveLLC NOThis garden. FOR SALE Darwin ORdeveloped DISTRIBUTION a deep respect for also causedNOT Darwin FOR a SALEgreat deal OR of DISTRIBUTIONmental anguish the organisms he studied and eventually abandoned (compare Figures 4.3, A and B). Emma was quite reli- hunting altogether. gious, and she and Charles learned not to speak directly Emma and Charles dearly loved one another and of Charles’s work, instead communicating about it by © Jones & Bartletthad 10 Learning, children, 2 of whomLLC died of disease and another,© Jones notes & whenBartlett necessary. Learning, LLC who was apparently mentally retarded, died at a young Charles Darwin died suddenly at Downe House. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION age. However, it was the loss of his beloved daughter, He had wished to be buried next to his children, but Anne Elizabeth (“Annie”), at the age of 10 that may after a state funeral he was entombed in Westminster have finally shaken Darwin’s belief in God once and Abbey, only a few feet away from Sir Isaac Newton, who for all; Darwin did not attend Annie’s funeral and could was at that time regarded as the preeminent scientist never bring himself© Jones to visit her& Bartlettgrave. Learning, LLCof all time. © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

When Wallace communicated with Darwin about his theory of evolution, Darwin began to panic. © Jones & Bartlett Learning, LLC At the suggestion© Jones of Lyell& Bartlett and other Learning, colleagues, DarwinLLC NOT FOR SALE OR DISTRIBUTION and WallaceNOT copublished FOR SALE a brief OR abstract, DISTRIBUTION and then Dar- win set to work on his On the Origin of Species, the first edition of which was published in 1859. Twelve hundred fifty copies of the first edition were printed and sold out overnight. Darwin was keenly aware of the implications © Jones & Bartlett Learning, LLC © Jonesof his & theoryBartlett for human Learning, evolution, LLC but he refrained from NOT FOR SALE OR DISTRIBUTION NOT FORtackling SALE this problemOR DISTRIBUTION in the Origin and only published his arguments later in The Descent of Man. Nevertheless, many lay people and scientists immediately understood the implications of Darwinian evolution for humans, and © Jones & Bartlett Learning, LLCit is therefore not surprising© Jonesthe Origin & receivedBartlett many Learning, LLC NOT FOR SALE OR DISTRIBUTIONnegative reviews when it wasNOT first FOR published. SALE OR DISTRIBUTION Basic Premises of Darwinian Evolution 4.4 Like Lyell had done in his Principles of Geol- © Jones & Bartlett Learning, LLC ogy (see© Chapter Jones 1), & Darwin Bartlett marshaled Learning, a mountain LLC NOT FOR SALE OR DISTRIBUTION of evidenceNOT to FORsupport SALE his theory OR inDISTRIBUTION the Origin. Based on this evidence he developed an inductive argument (see Chapter 1) for his theory based on a number of premises. As noted previously two basic observations led to Darwin’s theory of evolution: the great diversity © Jones & BartlettFigure 4.5Learning, Alfred Russel LLC Wallace (1823–1913). Wallace’s© Jones of plants& Bartlett and animals Learning, and their LLC biogeographic distri- NOT FOR SALEmiddle OR name DISTRIBUTION resulted from a misspelling on his birth certificate.NOT FORbution. SALE The fundamentalOR DISTRIBUTION questions, then, were how

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. did diversity arise and how did the organisms come © Jonesindividuals, & Bartlett those with Learning, less suitable LLC variations, whereas © Jones to& liveBartlett in different Learning, areas? Darwin LLC had to develop a sat- fitter individuals survive. Darwin called the struggle for NOT FORisfactory SALE mechanism OR DISTRIBUTION for evolution to occur. It was not NOTexistence FOR SALEnatural selectionOR DISTRIBUTION; he coined the term based on enough just to say that evolution occurred; Darwin had artificial breeding or selection, which is still used today to say how evolution occurred. Scientists are extreme to produce more productive lines of plants and animals skeptics until a particular mechanism (cause) can be for food. If there is natural selection, with unfit individu- identified that accounts© forJones a particular & Bartlett effect. UnfortuLearning,- alsLLC weeded out, then, Darwin© reasoned, Jones there & Bartlett must be Learning, LLC nately for Darwin, he neverNOT found FOR the SALE exact mechanism OR DISTRIBUTION differential reproduction: SurvivorsNOT FOR live long SALE enough OR DISTRIBUTION (for reasons we discuss shortly), but Darwin reasoned to reproduce and pass their more favorable traits to that tiny differences occurred in the natural variation their offspring so there is descent with modification. of organisms and that these variations could be passed In this way natural selection for more “fit” individuals from one generation to the next. Another of Darwin’s occurs over long intervals of time. Thus, depending basic ©premises Jones was & that Bartlett plant and Learning, animal populations LLC do on how one ©wants Jones to view & Bartlettit, natural Learning,selection acts LLC as not growNOT unchecked. FOR SALE Darwin OR therefore DISTRIBUTION reasoned there negative feedbackNOT (see FOR Chapter SALE 1) onOR unfit DISTRIBUTION individuals must be a “struggle for existence” that eliminates “unfit” or as positive feedback on more fit ones (Box 4.3).

Darwin based his thinking in part on Thomas Malthus’ food supplies to sustain human populations over much Essay on the Principle© ofJones Population, & Bartlett first published Learning, in ofLLC Earth. The massive starvation© predicted Jones by& MalthusBartlett Learning, LLC 1797 (Wallace had alsoNOT read FOR Malthus’ SALE book ORsome DISTRIBUTION time has not occurred in developedNOT countries, FOR but SALE famine OR DISTRIBUTION before his bouts with malaria). Malthus’ views, along has indeed occurred frequently in underdeveloped with those of others of the time, have echoed down countries with large populations. Today, many believe to the present and have often been misused. Thomas biotechnology holds the greatest promise for sustaining Malthus© Jones believed & Bartlett“the passion Learning, between the LLCsexes” was human populations,© Jones even & as Bartlett expanding Learning, populations LLC tooNOT great FORto overcome; SALE thus, OR human DISTRIBUTION populations would continue to impactNOT the FOR environment SALE OR(see DISTRIBUTIONChapter 17). increase “geometrically” (or exponentially), meaning that By all accounts Darwin’s sociopolitical views were after a slow increase, human population would sud- “Whiggish,” meaning he was inclined toward what we denly skyrocket upward. In contrast, according to Malthus, now consider a moderate-to-liberal social and politi- agricultural food production would increase at a much cal viewpoint. Unfortunately, Darwin’s adaptation of © Jones & Bartlettslower arithmetic Learning, rate, behaving LLC like a straight line. Thus, © JonesMalthus’ & views Bartlett continued Learning, to be used LLC to espouse what NOT FOR SALEaccording OR to DISTRIBUTIONMalthus, starvation would always be part NOTis calledFOR socialSALE Darwinism OR DISTRIBUTION, in which society is sup- of the human condition. Malthus also concluded that posed to improve by the action of natural selection poverty was natural and could never be eradicated, and on human efforts: some persons naturally succeed, there should be no attempts at state support of the poor. whereas others fail. One of the most notable per- Malthus, not Darwin, first coined the phrase “struggle for sons identified with social Darwinism was Herbert existence” in his description© Jones of primitive & Bartlett tribes andLearning, be- Spencer LLC (1820–1903), who© emphasized Jones & laissez-Bartlett Learning, LLC lieved that in his own NOTsociety FORcompetition SALE was OR best DISTRIBUTIONfor all. faire economic views. SpencerNOT certainly FOR believed SALE in OR DISTRIBUTION However, Malthus was perhaps not as ruthless as societal progress, but he also believed it should occur social reformers of the time portrayed him. Malthus in a Lamarckian-style “upward striving” of individu- believed the wealthy had not become rich because als, not through natural selection. Still others claim they© possessedJones & superior Bartlett abilities, Learning, and he viewed LLC wealth that the strongly© Jones pro-Darwin & Bartlett stance ofLearning, the famous LLC asNOT a responsibility FOR SALE that required OR DISTRIBUTION its use to help society in German zoologist,NOT E FORrnst Haeckel, SALE planted OR DISTRIBUTION the seeds of terms of employment and progress. He also advocated the National Socialist (Nazi) movement in Germany educating the poor in an attempt to eliminate poverty. and Austria. These and other movements, not just Today, Malthus is viewed by some as an alarmist. in Germany but also in Great Britain and America, As the human population has increased, technologic promoted the movement of racial stereotyping and © Jones & Bartlettbreakthroughs Learning, have generally LLC increased the ability of © Jonesselective & breeding Bartlett of humansLearning, called LLC eugenics. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Darwin also argued that natural selection of the © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC small differences between organisms could account for NOT FOR SALE OR DISTRIBUTION NOT FOR SALEtrends OR seen DISTRIBUTION in the fossil record. Thus, Darwin became keenly aware of the tremendous amount of time required for natural selection to produce evolutionary change. This is not unlike Lyell’s view of slow, gradual change through time, except© Jones that Darwin’s & Bartlett theory Learning,resulted in LLC © Jones & Bartlett Learning, LLC directional change,NOT something FOR SALELyell initially OR DISTRIBUTION rejected NOT FOR SALE OR DISTRIBUTION (see Chapter 1).

Concept and Reasoning Checks ©1. JonesWhat were & someBartlett of the Learning, basic observations LLC Darwin © Jones & Bartlett Learning, LLC NOTmade FOR during SALE the voyageOR DISTRIBUTION of the Beagle? NOT FOR SALE OR DISTRIBUTION 2. What are the basic tenets of the theory Darwin developed after his return to England?

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 4.5 Inheritance and Variation To make his theory of evolution credible, Figure 4.6 Gregor Mendel (1822–1884). Darwin had to provide© Jones evolution & Bartlett with a mechanism Learning, LLC © Jones & Bartlett Learning, LLC of inheritance. HeNOT already FOR knew, SALE based ORon the DISTRIBUTION experi- NOT FOR SALE OR DISTRIBUTION ments of animal breeders, that agricultural stocks had been improved to feed the expanding human popula- named Gregor Mendel (Figure 4.6). About the mid- tion, so there was obviously some sort of mechanism 1860s Mendel conducted experiments involving the for© Jonesparental &traits Bartlett to be passed Learning, to the offspring.LLC This crossing© of Jonespure-breeding & Bartlett lines of Learning, peas in the gardensLLC sameNOT mechanism, FOR SALE he ORreasoned, DISTRIBUTION would result in the of a monasteryNOT FOR in Brünn SALE (Brno), OR inDISTRIBUTION what is now the gradual modification of traits over many generations Czech Republic. Based on the results of many different in natural populations. Up to and after Darwin’s time, kinds of experimental crosses, Mendel concluded that Lamarck’s theory of acquired characteristics was one of genetic traits occurred in pairs (one each from the male only two theories of inheritance that had been suggested. and female) called alleles. Alleles behaved like particles, © Jones & BartlettThe other Learning, widely accepted LLC theory of inheritance© in Jonesand & Mendel’s Bartlett theory Learning, came to beLLC called the particulate NOT FOR SALEDarwin’s OR time DISTRIBUTION was that of blending inheritance, whichNOT FORtheory SALE of inheritance OR DISTRIBUTION. Alleles were either dominant or stated the traits of individuals were simple blends of recessive. Mendel reasoned that a recessive trait was those of its parents, like mixing a bucket of red and only expressed when both alleles were recessive (now white paint to produce pink. Based on Lamackian called homozygous recessive); otherwise, the domi- theory and blending© Jones inheritance, & Bartlett Darwin Learning,developed LLCnant trait was expressed if© both Jones alleles & were Bartlett dominant Learning, LLC his own theory ofNOT inheritance: FOR SALE “pangenesis.” OR DISTRIBUTION Darwin (homozygous dominant) NOTor if the FOR dominant SALE allele OR was DISTRIBUTION suggested that each organ of an individual’s body devel- present in just one “dose” (heterozygous). Thus, even oped special particles called “gemmules,” which were if organisms appear outwardly identical, they may be transported by the bloodstream to the gonads (testes different genetically. However, even if organisms are or ovaries). Because the gemmules originated in the genetically identical, they may still appear slightly body’s© Jones cells, &they Bartlett could take Learning, on characteristics LLC in the different.© GeneticallyJones & Bartlett identical Learning,twins, for example, LLC mannerNOT FOR Lamarck SALE had described.OR DISTRIBUTION Each offspring would typicallyNOT have FORslightly SALE different OR appearances DISTRIBUTION because be a blend of gemmules from both parents, although in of slight differences in environment (different diets, some cases the offspring might receive more gemmules etc.). We must therefore differentiate between “geno- from one parent than the other. type” and “phenotype.” The term genotype refers to the © Jones & Bartlett TheLearning, discovery ofLLC the basic mechanism of inheri©- Jonesactual & Bartlett genetic makeup Learning, of the organismLLC (homozygous NOT FOR SALEtance ORis rightfully DISTRIBUTION attributed to an Augustinian monkNOT FORdominant, SALE heterozygous, OR DISTRIBUTION or homozygous recessive);

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. phenotype refers to a particular genotype plus the ef- also originated from changes, or mutations, to certain © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC fects of the environment on the genotype. Mendel’s portions of the genetic material called genes; at the NOT FOR SALE OR DISTRIBUTION NOT FORparticulate SALE OR theory DISTRIBUTION of inheritance was highly signifi- time it was thought that a particular gene coded for cant, because it contradicted the blending theory of a particular trait. Mutations resulted in even greater inheritance. Unfortunately, Mendel published the re- amounts of genetic recombination than gametogen- sults of his work in a rather obscure journal, so the esis alone. In fact, mutations are now recognized as significance of his results© Jones lay dormant & Bartlett until Learning,around providingLLC the “raw material”© Jonesupon which & Bartlett natural Learning, LLC the turn of the century.NOT Later, FOR workers SALE discovered OR DISTRIBUTION that selection acts. But what was NOTthe exact FOR genetic SALE mate OR- DISTRIBUTION Mendel had sent a copy of his paper to Darwin, but rial in the chromosomes, its structure, and chemi- Darwin apparently never read it. cal composition? Answers to these questions would Still, two basic questions remained: what were show how the genetic information was encoded and the particles© Jones and &how Bartlett did they Learning, behave when LLC observed passed on to© offspring. Jones & Bartlett Learning, LLC underNOT the microscope? FOR SALE If theOR particles DISTRIBUTION could be iden- The NOTfact that FOR deoxyribonucleic SALE OR DISTRIBUTION acid, or DNA, tified, then perhaps their exact behavior could be serves as the hereditary code was not established until understood. During the last half of the 19th century the 1940s. The actual structure of DNA was determined chromosomes (“colored body”) were found to dupli- shortly thereafter in the 1950s, with the bulk of the cate and separate from one another during cell division credit normally given to James Watson (a geneticist) and © Jones &and Bartlett were therefore Learning, thought LLC to be involved in heredity. © JonesFrancis &Crick Bartlett (a biochemist). Learning, The fundamental LLC building NOT FORThen, SALE Mendel’s OR DISTRIBUTION results were rediscovered about 1900, NOTblocks FOR of DNASALE are OR called DISTRIBUTION nucleotides (adenine, guanine, and their full significance for heredity and the produc- thymine, and cytosine); nucleotides are attached to a tion of variation was realized. Each species has a char- double-stranded “spiral staircase” composed of sugars acteristic number of chromosomes. The number varies and phosphates (Figure 4.7). substantially between© species Jones and & doesBartlett not indicate Learning, LLC The sequence of nucleotides© Jones along & Bartlettthe sugar- Learning, LLC the species’ level of evolutionaryNOT FOR complexity.SALE OR When DISTRIBUTION phosphate backbone comprisesNOT the FORgenetic SALE code. The OR DISTRIBUTION gametes (sperm and egg) are produced by the process code is “decoded” to produce other molecules and of gametogenesis the chromosomes are shuffled much structures according to the Central Dogma of cell bi- like a deck of cards. During gametogenesis one half ology. The Central Dogma of cell biology states the of each duplicated pair of chromosomes has an equal genetic code stored in DNA is read by the process of © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC chance of going into one of the two cells resulting transcription to produce messenger RNA (mRNA), and fromNOT each cellFOR division. SALE ThisOR DISTRIBUTIONis much like flipping the messageNOT turned FOR into SALEother molecules OR DISTRIBUTION and struc- a coin, during which one has a 50:50 chance of ob- tures. The mRNA is single stranded, and once it has taining heads or tails. Thus, the potential number of been synthesized from DNA it is released from the DNA chromosome combinations (and therefore potential and travels out of the cell nucleus to the cell’s cyto- © Jones &genotypes Bartlett of gametes)Learning, is equal LLC to 2 raised to the power © Jonesplasm. The& Bartlett mRNA is Learning, read or translated LLC into proteins NOT FORof SALE the number OR DISTRIBUTION of pairs of chromosomes. In humans NOTin FORthe cytoplasm. SALE OR In diagrammatic DISTRIBUTION form, the chromosome number is 46, so there are 23 pairs of chromosomes. So, the total number of different DNA → mRNA → protein genotypes of gametes in humans (excluding mutation, discussed in Section 4.6 below) is 223, or about © Jones & Bartlett Learning, LLC There are three main ©types Jones of molecules & Bartlett in all Learning, LLC 8.4 million! No wonder there was so much variation NOT FOR SALE OR DISTRIBUTIONcreatures: carbohydrates (sugars),NOT FORlipids SALE(fats), and OR DISTRIBUTION within the same species: gametogenesis and sexual proteins. Although carbohydrates and lipids are both reproduction resulted in genetic recombination that involved in metabolism and growth, neither is par- produced vast numbers of genotypes on which natural ticularly different from one species to another. It is selection could act. the proteins that give each species its characteristics. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Proteins occur as structural proteins that give a cell 4.6NOT Genetic FOR SALECode andOR DISTRIBUTIONMutation shape and aidNOT in cellularFOR SALE movement OR andDISTRIBUTION as organic Still, this was not the complete picture of catalysts called enzymes. Each enzyme molecule con- heredity and variation. Breeding experiments es- sists of one or more proteins, which in turn consist of tablished that changes in the appearance of certain strands of amino acids (Figure 4.8). After each strand © Jones &portions Bartlett of chromosomes Learning, correspondedLLC to certain al- © Jonesis initially & Bartlett produced, Learning, it “balls up” LLCinto a characteristic NOT FORterations SALE inOR body DISTRIBUTION parts and coloration. Thus, variation NOTshape FOR based SALE on the OR distribution DISTRIBUTION of positive and negative

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. charges and the strength of chemical bonds (Figure 4.8). © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC One or more of the protein balls then forms the actual TA NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION enzyme molecule. CG AT Enzymes are highly specific for certain biochemical reactions. In these reactions an enzyme mol- CG ecule binds with a substrate molecule for much, much © JonesCG & Bartlett Learning,Parent duplex LLCless than a split second; the© enzyme Jones catalyzes & Bartlett the chem Learning,- LLC GC NOT FOR SALET A OR DISTRIBUTIONical change in the substrateNOT (perhaps FOR a SALEchemical OR bond DISTRIBUTION is broken or made, or a particular chemical grouping CG changed slightly), and then the altered substrate mol- T A CG ecule is released for use in another reaction. The en- © Jones & BartlettTA Learning, LLC zyme molecule© Jones and &its Bartlettsubstrate moleculeLearning, react LLC at the NOT FOR SALE OR DISTRIBUTION enzyme’sNOT active FOR site. TheSALE active OR site DISTRIBUTION is highly specific TA for the substrate molecule because of the distribution A T A T of positive and negative charges at the active site and C G because of the active site’s shape. Thus, the substrate C G CG behaves like a key inserted into the lock represented © Jones & Bartlett Learning, LLC GC © Jones & Bartlett Learning, LLC G C T A by the enzyme (Figure 4.8). If any changes to the active NOT FOR SALE OR DISTRIBUTIONT NOT FOR SALE OR DISTRIBUTION Daughter A site’s structure or the distribution of positive or negative duplex CG charges occur because of a mutation, it is very likely C G T A T A that the enzyme will be dysfunctional. An important C G CG T A step in a metabolic pathway might not be catalyzed TA © Jones & Bartlett Learning, LLCproperly, and the organism© Joneswould likely & Bartlett die. Learning, LLC T A TA Template Thus, mutations are typically lethal. Neverthe- A T NOT FOR SALE ORT DISTRIBUTION NOT FOR SALE OR DISTRIBUTION strands A less, some mutations are beneficial, or at least “neutral,” and so may persist in natural populations rather than

Replica being weeded out by natural selection. Mutations, strands coupled with the process of genetic recombination, © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC (a) are acted on by natural selection to produce evolution- NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION H ary change that results in new species.

NH N H3C O Adenine Concept and Reasoning Checks Thymine N H N N O 1. What processes produce genetic variation? © Jones & Bartlett Learning,N LLC N © Jones & Bartlett Learning, LLC O 2. What is the importance of enzymes and how do NOT FOR SALE OR DISTRIBUTIONO Deoxyribose NOT FOR mutationsSALE OR potentially DISTRIBUTION affect enzyme function? Deoxyribose H

N H O N © Jones & Bartlett GuanineLearning, LLC © Jones & Bartlett Learning, LLC Cytosine N H N A N NOT FOR SALE OR DISTRIBUTIONO NOT FOR SALE OR DISTRIBUTION N O N Evidence for Natural Selection O NH Deoxyribose 4.7 Despite the voluminous evidence that Darwin Deoxyribose H (b) marshaled in support of his theory of evolution and de- Figure© Jones 4.7 t&he Bartlett basic structure Learning, of DNA. (a) LLC The double spite the© theory’s Jones wide & Bartlettexplanatory Learning, power, Darwin LLC regarded natural selection as a hypothesis. Darwin based helixNOT unwinds FOR in SALE order to ORduplicate DISTRIBUTION itself or to be transcribed NOT FOR SALE OR DISTRIBUTION to produce messenger RNA. The nucleotides along the the hypothesis of natural selection on artificial breeding unwound strands of DNA serve as templates which are read experiments and the fact that natural populations do to produce the complementary strands. (b) Complementary nucleotides along the helices bond through weak hydrogen not exhibit wild fluctuations in abundance. Darwin bonds (red dots). The hydrogen bonds are easily broken and further supported his hypothesis through his studies © Jones & Bartlettre-made during Learning, DNA duplication LLC and transcription. © Jonesof sexual& Bartlett selection Learning,. Sexual selection LLC acts on mating NOT FOR SALE OR DISTRIBUTION NOT FORsuccess, SALE either OR through DISTRIBUTION competition of the members

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & Bartlett Learning,Lock-and-k LLC ey model © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONEnzyme NOT FOR SALE OR DISTRIBUTION Substrate

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Active Products NOT FOR siteSALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Figure 4.8 the enzyme lock-and-key mechanism. [Adapted from: Mathews, C. K., van Holde, K. E., and Ahern, K. G., 1999. Biochemistry, 3rd ed. Upper Saddle River, NJ: Prentice Hall.]

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC of oneNOT sex ofFOR a species SALE for ORmates, DISTRIBUTION through choices by in natural populations,NOT FOR became SALE theOR dominant DISTRIBUTION form members of the opposite sex, or some combination. because birds served as a selective agent and were more Sexual selection results in what are seemingly bizarre likely to prey on lighter-colored moths. With the decline mating rituals and exaggerated phenotypes such as of coal use in later years, the original peppered color- © Jones &beautiful Bartlett coloration Learning, in birds LLC or large antlers in elk and © Jonesation spread & Bartlett once again Learning, through most LLC of the population. other mammals. NOT FOR SALE OR DISTRIBUTION NOT FOR ItSALE is now knownOR DISTRIBUTION that the black allele is a domi- Since Darwin’s time a number of cases of natu- nant allele and the white is recessive. Thus, the natural ral selection have been well documented that further populations before the onset of pollution were repre- substantiate his hypothesis. The most famous exam- sented by animals that were homozygous recessive for ple is industrial melanism in England (“melanic” refers the white allele. This sort of natural selection is referred to dark colored). During© Jones the industrial & Bartlett revolution Learning, in toLLC as directional selection, because© Jones the genotypes & Bartlett in the Learning, LLC England pollution controlsNOT wereFOR unheard SALE ofOR and DISTRIBUTION the population are dominated by NOTone genotype. FOR SALE Although OR DISTRIBUTION countryside, especially around the heavily-industrialized dominant mutations normally spread quickly, even af- city of Manchester, was often blackened with the soot ter many generations, they still do not comprise 100% from the burning of coal. Consequently, the background of genotypes of the population (Figure 4.10). On the on which© Jones the peppered & Bartlett moth, Learning, Biston betularia, LLC lived other hand, even© Jones though & recessive Bartlett mutations Learning, normally LLC beganNOT to darken FOR ( FigureSALE 4.9 OR). A DISTRIBUTION similar phenomenon take many generationsNOT FOR to SALEspread, theyOR canDISTRIBUTION still spread occurred among other species of insects. The peppered quite rapidly because of directional selection. look of the moth had originally served to camouflage Other examples of natural selection are related it from predators, especially birds. As tree trunks and to the role of medicine and agriculture in society. For other substrates were darkened by soot, black moths, example, natural selection also acts in the case of © Jones &which Bartlett were alwaysLearning, present LLC in very small numbers © Jonessickle-cell & anemia.Bartlett Sickle-cell Learning, anemia LLC is found mainly in NOT FOR SALE OR DISTRIBUTION NOTAfrican-Americans FOR SALE OR and DISTRIBUTION causes the collapse of red blood cells so they have a crescent (sickle)-shaped appearance rather than a disc-like appearance (Figure 4.11). Sickled red blood cells carry less oxygen to the body’s tissues and © Jones & Bartlett Learning,organs, LLC resulting in fatigue or death.© Jones Sickle-cell & Bartlett anemia Learning, LLC NOT FOR SALE OR DISTRIBUTIONresults from a single slight mutationNOT FORin the DNASALE code. OR DISTRIBUTION (a) This mutation affects the ability of the protein, hemoglobin, in red blood cells to bind oxygen. (b) Sickle-cell anemia was originally widespread in tropical Africa. Malaria is also widespread there © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC because of heavy rainfall and standing water, which NOT FOR SALE OR DISTRIBUTION mosquitoes NOT(the vectors FOR or SALE carriers OR of theDISTRIBUTION disease) use for breeding (Figure 4.12). Malaria is actually caused by a protist that infects red blood cells and causes them Figure 4.9 Industrial melanism in the peppered moth, to burst (hence, the fever associated with malaria). © Jones &Biston Bartlett betularia Learning, on a (a) dark (melanic)LLC and (b) pale, “pep- © JonesHowever, & theBartlett protist Learning,cannot infect LLC sickled cells. Thus, NOT FORpered” SALE form. OR DISTRIBUTION NOThumans FOR eitherSALE homozygous OR DISTRIBUTION dominant for the allele

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Author ISBN # Author's review Martin 80012 (if needed) Fig. # Document name OK Correx F04.10 80012_CH04_FIG10.eps Artist Date Initials Date 06/19/2011 Accurate Art, Inc. Check if revision CE's review B x W 2/C 4/C OK Correx

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100 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION90 NOT FOR SALE OR DISTRIBUTION 80 70 Dominant 60 © Jones50 & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT40 FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 30 Percentage of population 20 Recessive 10 © Jones & Bartlett0 Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR10000 DISTRIBUTION20000 30000 40000 50000 60000 70000NOT80000 FOR90000 SALE100000 OR110000 DISTRIBUTION Number of generations Figure 4.10 Spread of dominant and recessive alleles in a hypothetical population of organisms. Notice that the dominant mutation spreads quickly, but even after many generations has still not spread completely through the population. On the other hand, the recessive mutation takes many generations to spread, but eventually spreads quite rapidly. [Adapted from: Patterson, C. 1978. Evolution, 1st ed. Ithaca, NY: British Museum of Natural History/Cornell University Press. Figure 23 (p. 73).] © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION for normal hemoglobin or homozygous recessive for Balancing selection is exhibited in other ways. the allele for sickle-cell anemia are more likely to In hybrid vigor crosses of inbred strains sometimes die of anemia or malaria, respectively, than individu- produce offspring that exhibit greater crop yields than the parent strains. Each parent strain is homozygous als that are heterozygous© Jones (Figure & Bartlett 4.12). IndividualsLearning, LLC © Jones & Bartlett Learning, LLC with one allele of each are more likely to get enough dominant or homozygous recessive for a particular NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION oxygen while avoiding infection of blood cells by allele that produces only one type of protein, whereas malaria. This example is one of balancing selection, the offspring are heterozygous for the allele. The off- in which a relatively stable proportion of genotypes spring therefore produce two types of proteins and may is maintained in a population by a selective force (in be at a selective advantage. In humans inbred strains this© Jones case, malaria). & Bartlett Learning, LLC are frequently© Jones homozygous & Bartlett recessive Learning, for genes LLC that NOT FOR SALE OR DISTRIBUTION produceNOT defects FOR that SALEare lethal; OR this DISTRIBUTION is why laws pro- hibit the marriage of first cousins, who are too closely related genetically (see Box 4.2). Another example of natural selection is antibiotic resistance. Bacteria grown in culture and treated © Jones & Bartlett Learning, LLC © Joneswith & antibioticsBartlett Learning, such as penicillin LLC quickly become NOT FOR SALE OR DISTRIBUTION NOT FORresistant SALE to the OR antibiotics. DISTRIBUTION Bacteria reproduce quite

Figure 4.12 the occurrence of sickle-cell anemia in tropical Africa. The highest occurrence is in tropical west Africa, from © Jones & Bartlett Learning, LLC © Joneswhere & mostBartlett slaves originated.Learning, [Adapted LLC from: Strickberger, M. W. NOT FOR SALEFigure OR 4.11 DISTRIBUTION Normal and sickled red blood cells. NOT FOR1985. SALE Genetics ,OR 3rd ed.DISTRIBUTION New York: MacMillan.]

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. quickly, often in a matter of hours, and if mutants resis- is not very high. The founder effect accounts for © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC tant to antibiotics appear they spread through the culture the establishment of the finch populations in the NOT FOR SALE OR DISTRIBUTION NOT FORpopulations SALE OR quite DISTRIBUTION rapidly. In recent years antibiotic Galápagos (Figure 4.4). Genetically different popu- use has become very widespread and so has antibiotic lations of finches settled on different islands, so that resistance. Thus, new antibiotics may have to be devel- the founding populations on each island were already oped in the future to counteract resistant bacteria. different at the outset. Another mechanism involved in Natural selection© Jones is also put& Bartlett to use in geneticLearning, speciationLLC involves genetic drift.© Jones In genetic & driftBartlett some Learning, LLC engineering. Genetic NOTengineering FOR SALEis the science OR DISTRIBUTION that genetic traits are simply lost NOTby chance FOR from SALE demes, OR DISTRIBUTION manipulates the DNA of viruses, bacteria, and other whereas others are passed on. In this way demes may organisms, including humans, and is used to increase also change genetically through time. the yield and disease resistance of crops. It is also being Given enough time, then, geographic isolation used ©to Jonescombat disease& Bartlett and birth Learning, defects in LLC humans. leads to reproductive© Jones isolation & Bartlett and allopatric Learning, specia LLC- NOT FOR SALE OR DISTRIBUTION tion. ReproductiveNOT FORisolation SALE may ORdevelop DISTRIBUTION because of 4.8 Speciation different seasonal times of reproduction, behavioral So we now know how genetic traits are passed differences associated with mating rituals, and so on. However, if the barriers to isolation are removed before from parents to offspring. But how do new species arise? reproductive isolation has been completed, the popula- This is really the question that Darwin and others were © Jones & Bartlett Learning, LLC © Jonestions can & stillBartlett interbreed. Learning, Populations LLC that have partly trying to answer. NOT FOR SALE OR DISTRIBUTION NOTdiverged FOR SALEfrom one OR another DISTRIBUTION but not developed into full- Mutations are spread through populations by fledged species are calledsubspecies . In humans these interbreeding. Thus, speciation could occur by geo- differences are less pronounced and are recognized as graphic isolation of populations so they are prevented races. Racial differences between humans are therefore from interbreeding. This type of speciation is known a matter of natural biologic evolution. For example, as allopatric speciation© . JonesBiologic &populations Bartlett areLearning, not LLC © Jones & Bartlett Learning, LLC dark skin is the result of the production of the dark uniformly distributed NOTover their FOR geographic SALE rangesOR DISTRIBUTION and NOT FOR SALE OR DISTRIBUTION pigment, melanin, that protects the skin from excessive typically consist of a main population with smaller sunlight in the tropics. isolated populations on their periphery. According to allopatric speciation new species originate by geo- Concept and Reasoning Checks graphic© Jonesisolation & of Bartlettlocal populations, Learning, called LLC demes or © Jones & Bartlett Learning, LLC 1. What is the difference between balancing and peripheral isolates, by rivers and streams, mountain NOT FOR SALE OR DISTRIBUTION directionalNOT selection? FOR SALE OR DISTRIBUTION chains, or changes in local climate from one side of 2. How might directional selection be involved in a valley to another, such as sunlight and moisture. speciation? Although the populations are reproductively isolated, 3. What is the difference between the founder they begin to diverge genetically from one another. If effect and genetic drift and why are both pro- © Jones &the Bartlett populations Learning, remain isolated LLC for a long enough time © Jones & Bartlett Learning, LLC cesses important to speciation? NOT FORfor SALE sufficient OR geneticDISTRIBUTION divergence to occur, the popula- NOT FOR SALE OR DISTRIBUTION tions become reproductively isolated from another and are therefore new species. Genetic transformation of the demes to new species may occur in several© Jones ways. & Obviously, Bartlett theLearning, ad- LLC © Jones & Bartlett Learning, LLC dition of mutations addsNOT more FOR variety SALE to the ORgenotypes DISTRIBUTION Evolution and theNOT Fossil FOR Record SALE OR DISTRIBUTION of demes, and mutations spread much more quickly 4.9 Much of the evidence so far marshaled in through small populations than large ones. Specia- support of evolution in this chapter has come from tion may be accelerated in small populations by two biology. However, as Darwin and his contemporaries other processes. In the founder effect a new deme is recognized, much of the basic evidence for evolution © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC not genetically representative of the original parent comes from the fossil record. populationNOT FORfrom whichSALE it ORcame. DISTRIBUTION Imagine a box full of NOT FOR SALE OR DISTRIBUTION solid black and solid white balls mixed together, from 4.9.1 Comparative anatomy which 10 balls are randomly chosen. The likelihood Some of the evidence for evolution in the fossil record that the proportion of black to white balls chosen (the was already well known before Darwin. For example, © Jones &deme) Bartlett is exactly Learning, the same LLC as the proportion in the © Jonesstudies &of comparativeBartlett Learning, anatomy recognized LLC two basic NOT FORmuch SALE larger OR collection DISTRIBUTION in the box (parent population) NOTkinds FOR of SALEstructures. OR Homologous DISTRIBUTION structures have a

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. common evolutionary ancestry but are dissimilar in tiles), and dolphins (mammals) (Figure 4.14). These © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC function, such as the limbs of mammals (Figure 4.13). groups are not closely related by evolution. Analogous NOT FOR SALEThese ORstructures DISTRIBUTION are similar because they share a comNOT- FORstructures SALE arise OR throughDISTRIBUTION convergent evolution, in mon ancestry, but they have evolved or diverged for which natural selection acts on very different taxa to different functions through divergent evolution. Con- evolve or converge on, for example, wings for flight or versely, analogous structures are similar in function but streamlined bodies for moving through water quickly. dissimilar in structure.© Jones Examples & Bartlett include the Learning, wings of LLCAlthough analogous structures© Jones are not & Bartlettused to deter Learning,- LLC birds, bats (mammals),NOT andFOR butterflies SALE ORand theDISTRIBUTION stream- mine evolutionary relationships,NOT FOR they SALEserve as ORyet an DISTRIBUTION- lined bodies of fish, ichthyosaurs (extinct marine rep- other example of the action of natural selection, namely

Human Lizard Cat Whale Bat © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Humerus

Ulna NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Radius

Frog Bird © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & BartlettFigure 4.13 Learning, Homologous LLC structures of the limbs of different© Jones mammals. & NumbersBartlett and Learning, colors refer to LLC bones with a common NOT FOR SALEevolutionary OR DISTRIBUTIONancestry. NOT FOR SALE OR DISTRIBUTION

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©Convergent Jones & ev Bartlettolution for Learning,sustained rapid LLC swimming in a marine habitat© Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Ancestral mammal © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Ancestral shark Ancestral reptile © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Ancestral fish Figure 4.14 Analogous© structures Jones arise & Bartlettthrough convergent Learning, evolution. LLC The streamlined bodies of fish,© ichthyosaursJones & (extinctBartlett Learning, LLC marine reptiles) and dolphinsNOT (mammals) FOR SALE arose throughOR DISTRIBUTION convergent evolution. If these three taxa wereNOT classified FOR into SALE the same OR DISTRIBUTION taxon based on body shape alone, the taxon would be a grade, not a clade. However, many other features indicate that these taxa are not closed related.

that depending© Jones on& theirBartlett habitat Learning, and niche, veryLLC differ- same traits. All© Jonessorts of traits & Bartlett have been Learning, used in cladis LLC- ent groups of organisms may evolve similar structures NOT FOR SALE OR DISTRIBUTION tics, ranging NOTfrom anatomic FOR SALE (for example, OR DISTRIBUTION the number because they are subject to the same selective pressures. and arrangement of bones in a skeleton) to the se- Because biologic classification is supposed to quences of nucleotides in DNA and RNA and amino represent true phylogenetic, or evolutionary, relation- acids in proteins. ships, all the members of a particular category must But the basic procedure in cladistics is always © Jones &be Bartlettdescended Learning, from a common LLC ancestor (see Box 4.1). © Jonesthe same. & BartlettThe basic Learning,assumption LLCof cladistics is that NOT FORSuch SALE taxa ORare called DISTRIBUTION clades, and for this reason branch- NOTtwo FOR taxa shareSALE the OR same DISTRIBUTION trait because they have a com- ing or divergent evolution is sometimes referred to as mon ancestry. These relationships are represented in cladogenesis. Clades are considered to be “monophyletic,” a cladogram like that shown for the major groups of meaning each represents a distinct taxon that reflects its vertebrates in Figure 4.15. All the vertebrate groups true evolutionary relationships. Taxa that do not share shown possess jaws. Such a trait, which is shared by all a common ancestry but© Jonesare mistakenly & Bartlett misclassified Learning, the LLC taxa, must have appeared first© Jones and is therefore& Bartlett con- Learning, LLC together are referred toNOT as grades FOR because SALE convergent OR DISTRIBUTION sidered primitive. Derived traitsNOT—lungs, FOR claws, SALE scales, OR DISTRIBUTION evolution has resulted in very different taxa attaining fur, and mammary glands—appear later in succession the same “grade” or superficial appearance. Such grades in each of the remaining vertebrate taxa: amphibians, are said to be “polyphyletic” because they include taxa reptiles, and mammals. Birds, which are characterized not closely© Jones related & evolutionarily.Bartlett Learning, LLC by feathers, ©are Jones probably & an Bartlett offshoot Learning,of small bipedal LLC NOT FOR SALE OR DISTRIBUTION dinosaurs (dinosaursNOT FOR that SALE walked ORor ran DISTRIBUTION on their hind 4.9.2 Cladistics legs) that appear to have used feathers for insulation. For many years evolutionary relationships were es- Mammals were probably also derived from another tablished based on simple comparisons of anatomy of group of reptiles that share certain anatomic features modern and fossil species like those described above. with mammals. © Jones &However, Bartlett the Learning, new science LLCof cladistics classifies taxa © Jones &Although Bartlett this Learning, particular cladogramLLC was con- NOT FORaccording SALE OR to whether DISTRIBUTION or not different taxa share the NOTstructed FOR forSALE higher OR taxonomic DISTRIBUTION categories (some major

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Lamprey SharkFrog Cow Monkey Human © Jones & Bartlett Learning, LLC © JonesNo tail & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION OpposaNOTble thumb,FOR SALE OR DISTRIBUTION stereovision Hair, mammary glands

Four limbs, lungs © Jones & Bartlett Learning, LLC Jaws, ©ver tebraJonese & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Figure 4.15 A cladogram of some vertebrates showing the successive appearance of major features through time at each branching point. Jaws are considered a primitive trait because all of the taxa, except lampreys, possess them, whereas the other features are said to be derived. [Adapted from: Prothero, D. R. 1998. Bringing Fossils to Life: An Introduction to Paleobiology, © Jones & Bartlett1st ed. New Learning, York: WCB/McGraw-Hill. LLC Figure 4.2 (p. 48).] © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION taxa of vertebrates), the same basic procedure is used and C. According to the cladogram A and C are more to examine the relationships at much lower levels, such closely related to each other than they are to B. as the species belonging to a particular genus or the Traditional evolutionary “trees” and clado- genera belonging to© aJones particular & family.Bartlett As before, Learning, more LLCgrams do not always yield© Jonesthe same & classifications, Bartlett Learning, LLC primitive traits areNOT thought FOR to SALEbe shared OR by DISTRIBUTION different however. For example, FigureNOT FOR 4.17 showsSALE a ORclado DISTRIBUTION- groups, whereas derived traits are shared by fewer gram of the relationships between humans and related groups. A hypothetical, evolutionary tree is shown in groups. The traditional classification places all humans Figure 4.16. Figure 4.16A implies time on the vertical in the same family, Hominidae, and other forms such scale, whereas the relative distances between taxa A, as gorillas and chimpanzees in the family Pongidae. B,© andJones C in the& Bartlett diagram roughlyLearning, correspond LLC to their In this view© Jones the families & Bartlett Hominidae Learning, and Pongidae LLC are anatomicNOT FOR differences, SALE ORwhich DISTRIBUTION presumably reflect their consideredNOT to FORbe monophyletic. SALE OR However, DISTRIBUTION this view evolutionary relationships. is undoubtedly highly anthropocentric, or “human These relationships are shown differently in centered.” Many workers view the family Pongidae a cladogram. Figure 4.16B represents the cladogram as being a “grab bag” or “wastebasket” of all taxa that © Jones & Bartlettof the common Learning, and derived LLC characters of taxa A,© B, Jonesare ¬ Bartlett considered Learning, “human”; LLCsuch a taxon is said to be “paraphyletic” because it does not include all of NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION its descendants. In fact, the cladogram in Figure 4.17 ACBB CAsuggests that humans basically lie on a continuum of traits they share with the other taxa. Thus, according to the alternative cladogram in Figure 4.17, orang- © Jones & Bartlett Learning, LLCutans, gorillas, chimpanzees,© Jones and humans & Bartlett should all Learning, be LLC X NOT FOR SALE OR DISTRIBUTIONplaced in the same taxon,NOT which FOR is in turn SALE considered OR DISTRIBUTION X monophyletic.

4.9.3 Microevolution Another way in which evolutionary relationships can (a)© Jones & Bartlett Learning,(b) LLC © Jones & Bartlett Learning, LLC be inferred from the fossil record is to trace the suc- FigureNOT FOR4.16 (a) SALE Traditional OR evolutionary DISTRIBUTION tree, in which phylo- NOT FOR SALE OR DISTRIBUTION genetic relationships are depicted between three taxa (A, B, and cession of different species through time in the sedi- C). Two taxa (A and C) share a newly derived character (X) and mentary record. For many decades, the succession of taxon B is ancestral to taxa A and C. Time is vertical (upward). species in the fossil record was viewed as occurring (b) Cladogram of relationships between A, B, and C. Note that in the cladogram, no indication of ancestry is shown. However, by slow, gradual processes collectively termed micro- © Jones & Bartlettboth diagrams Learning, indicate that LLC A and C are more closely related ©to Jonesevolution & Bartlett. Microevolution Learning, was LLC thought to result from NOT FOR SALEone another OR DISTRIBUTION(because they both share “X”) than to B. NOT FORthe kinds SALE of ORshort-term DISTRIBUTION genetic processes like those

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Change in thermal stability (°C) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning,876543210 LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Human Homo sapiens

Gorilla © Jones & Bartlett Learning, LLC © JonesGorilla & gorillaBartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOROrangutan SALE OR DISTRIBUTION Pongo pygmaeus

Common gibbon Hylobates lar

Old World monkeys Cercopithecidae

35© Jones 30 & 25 Bartlett 20 Learning, 15 LLC 10 50 © Jones & Bartlett Learning, LLC Millions of years ago Figure 4.17 the evolutionaryNOT relationshipsFOR SALE of humans OR DISTRIBUTION portrayed by a standard evolutionary tree. ThisNOT particular FOR tree SALE is based ORon DISTRIBUTION the thermal stability of DNA, which has been used as a measure of evolutionary relationships between different taxa. [Adapted from: Sibley, C. G. and Ahlquist, J. E. 1984. The phylogeny of the hominoid primates, as indicated by DNA–DNA hybridization. Journal of Molecular Evolution 20, 2–15.]

documented© Jones in genetic & Bartlett experiments Learning, and biogeographic LLC in the pseudoextinction© Jones & of Bartlettthe first species.Learning, Although LLC studiesNOT of the FOR distribution SALE ORof species. DISTRIBUTION anagenesis wasNOT often FOR inferred SALE from OR the DISTRIBUTIONfossil record, it The pattern of speciation in the fossil record was rarely observed. The lack of observed transitions that was thought to result from microevolution was was therefore dismissed as an artifact of the geologic referred to as phyletic gradualism (Figure 4.18). The record due to nonpreservation or erosion. © Jones &gradual Bartlett transition Learning, of one species LLC into another is called © Jones &However, Bartlett an Learning, alternative modeLLC of speciation anagenesis (as opposed to cladogenesis) and results was developed in the 1970s by the paleontologists NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 75 75

60 60 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 45 NOT FOR SALE OR45 DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

30 30 Time (my) Time (my) Time (my)

15 15 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT0 FOR SALE OR DISTRIBUTION0 NOT FOR SALELeg lengthOR DISTRIBUTION (a) (b) (c) Figure 4.18 Modes of evolution suggested by the fossil record. (a) Phyletic gradualism, which represents slow, gradual evolution. (b) Punctuated equilibrium, which is basically the record of allopatric speciation in the fossil record. Occasionally, following punctuated speciation, lineages persist to the present essentially unchanged as living fossils. (c) A hypothetical example of species sorting, in which species lineages are “pruned” sometime after they appear, and which may cause lineages © Jones &to Bartlettevolve in new Learning, directions. [Adapted LLC from: Stanley, S. M. 1989.© JonesEarth and & Life Bartlett Through TimeLearning,, 2nd ed. NewLLC York: W.H. NOT FORFreeman SALE & OR Company.] DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Niles Eldredge and Stephen Jay Gould called punctu- famous living fossils is the coelacanth, which belongs © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ated equilibrium. These workers argued that the fossil to the same taxon (lobe-finned fishes) that gave rise NOT FOR SALErecord OR was DISTRIBUTION not nearly as incomplete as most workersNOT FORto amphibians SALE OR (see DISTRIBUTION below). had said and that apparent phyletic gradualism re- Punctuated equilibrium explains a common ally represented long intervals of slow, nondirectional misconception of creationists regarding what are called change (what they called “stasis”) punctuated by abrupt missing links. The term “missing link” builds on the appearances of new© speciesJones (Figure & Bartlett 4.18). PunctuatedLearning, LLCconcept of the Chain of Being.© Jones Missing & Bartlett links are taxaLearning, LLC equilibrium is basicallyNOT FORa record SALE of allopatric OR DISTRIBUTION specia- that are intermediate in theirNOT traits FOR between SALE one OR taxon DISTRIBUTION tion preserved in the fossil record (Figure 4.19). Ac- and another. A prime example is Archaeopteryx, which cording to this theory the main parental population is commonly considered to be the first bird. Archaeop- dominates in the fossil record because it is widespread teryx possesses the traits of both reptiles (teeth, long and therefore more likely to be preserved and eventu- © Jones & Bartlett Learning, LLC tail, claws)© andJones birds &(hollow Bartlett bones, Learning, feathers). However, LLC ally found. However, occasionally the main population NOT FOR SALE OR DISTRIBUTION missing NOTlinks like FOR Archaeopteryx SALE OR are DISTRIBUTION rare. Creationists goes extinct and disappears from the fossil record. At argue that if evolution occurs, there should be many this time the peripheral isolates that have been present more examples of missing links in the fossil record. all along (but not preserved in the fossil record because However, evolution in relatively small populations such of their patchy distribution and small population sizes) as peripheral isolates means that it is unlikely missing © Jones & Bartlettexpand and Learning, radiate into LLC the environment left vacant© Joneslinks & areBartlett preserved Learning, in the fossil LLC record. NOT FOR SALEby the OR extinction DISTRIBUTION of the main population (Figure 4.19).NOT FOR SALE OR DISTRIBUTION The peripheral isolates therefore appear suddenly in the fossil record as new species. Recent studies of over Concept and Reasoning Checks 100 animal, plant, and fungal lineages suggest that 1. How does the use of homologous and analogous new species may evolve in these peripheral isolates © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC relatively rapidly, as would be expected given their structures to infer evolutionary relationships differ small population NOTsize and FOR the potentialSALE OR for the DISTRIBUTION spread from the use of cladograms?NOT FOR SALE OR DISTRIBUTION of mutations that might result in reproductive isolation. 2. Indicate where the processes of allopatric specia- Once established, these species settle down to stasis tion are taking place next to a diagram of punctu- once again. Usually, the taxa established by the periph- ated equilibrium. eral© Jones isolates &eventually Bartlett go Learning, extinct or are LLC replaced, but 3. Why© is Jones population & Bartlett size important Learning, to speciation? LLC onNOT rare FORoccasions SALE lineages OR DISTRIBUTIONmay persist to the present NOT FOR SALE OR DISTRIBUTION essentially unchanged as living fossils. One of the most

Time and appear in fossil record Parent lineage © Jonesdies & outBartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT FOR SALE OR DISTRIBUTIONParent population NOT FOR SALE OR DISTRIBUTION terminates fossil record

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION Peripheral isolate NOT FOR SALE OR DISTRIBUTION Figure 4.19 the relation of allopatric speciation to punctuated equilibrium. Allopatric speciation is the process by which new species arise while punctuated equilibrium is the pattern of allopatric speciation preserved in the fossil record. The parent population persists relatively unchanged and is more likely to be found in the fossil record than peripheral isolates because of the parent population’s larger numbers and geographic extent. However, if the parent population dies out, one or more of the peripheral isolates will move into the vacated habitat and expand in numbers and geographic area so that new species will be found sud- © Jones & Bartlettdenly appearing Learning, in the fossil LLC record. The new species will then© Jones remain relatively & Bartlett unchanged Learning, because of LLC their large population size. NOT FOR SALEHowever, OR they DISTRIBUTION too may eventually go extinct, so that the patternNOT is FORrepeated SALE in the fossilOR record.DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. One of the earliest pieces of evidence cited © Jones 4.9.4& Bartlett Macroevolution Learning, LLC © Jones & Bartlett Learning, LLC in support of macroevolution was the biogenetic law NOT FORThe SALE fossil ORrecord DISTRIBUTION reveals other evolutionary patterns NOT FOR SALE OR DISTRIBUTION and therefore perhaps other evolutionary processes. proposed by the German zoologist, Ernst Haeckel, in Indeed, the fossil record indicates that new species or the later 1800s (Box 4.3). The biogenetic law is usually taxa belonging to categories higher than species may stated as “ontogeny tends to recapitulate phylogeny.” evolve because of rapid genetic change, or macro- This means the development of the individual or- evolution, in small populations.© Jones & Bartlett Learning, ganismLLC (ontogeny) reflects© (recapitulates) Jones & Bartlett its evo- Learning, LLC The couplingNOT of Darwinian FOR SALE evolution OR DISTRIBUTION with lutionary relationships or phylogenyNOT FOR (evolutionary SALE OR DISTRIBUTION modern genetics is often referred to as the modern history). The prime example is the appearance and synthesis or neo-Darwinism. The modern synthesis ap- later disappearance of gill slits (which are used for peared after World War II and has strongly influenced breathing by fish) during the early development of evolutionary© Jones thought & Bartlett to the present Learning, day. The LLC modern the human embryo© Jones (Figure & Bartlett 4.20). TheLearning, appearance LLC synthesisNOT dismissed FOR SALE macroevolution OR DISTRIBUTION because of the of gill slits duringNOT FORhuman SALE embryonic OR DISTRIBUTION development results of genetic experiments on human time scales. presumably reflected the fact that humans were ulti- These experiments indicated that large-scale mutations mately descended from fish and was frequently cited that presumably had to occur to cause rapid or drastic in older textbooks as proof of evolution. However, evolutionary change normally do not occur and that the biogenetic law was later downplayed because it © Jones &when Bartlett they do Learning, they are lethal. LLC Instead, evolutionary © Joneswas realized & Bartlett that embryologic Learning, development LLC is far, far NOT FORbiologists SALE ORopted DISTRIBUTION for slow, microevolutionary changes NOTmore FOR complex SALE than OR such DISTRIBUTION a sequence of figures like in the occurrences of genotypes within populations. that in Figure 4.20 suggests.

Fish Salamander Tortoise Chicken Pig Cow Rabbit Human © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Pharyngeal (gill) arches

Figure 4.20 early embryonic development of different vertebrates according to Ernst Haeckel. Note the appearance and loss of © Jones &gill Bartlettslits, which wasLearning, used in support LLC of the biogenetic law. [Reproduced© Jones from: G.& J.Bartlett Romanes. 191Learning,0. Darwin, andLLC After Darwin, First NOT FORedition. SALE Chicago, OR I.L.:DISTRIBUTION The Open Court Publishing Company.] NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. In retrospect, however, Haeckel had discov- occur along the length of chromosomes, almost like © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC ered something of tremendous importance. Recently, beads on a string, with each bead corresponding to a NOT FOR SALEscientists OR haveDISTRIBUTION discovered regulatory genes calledNOT FORparticular SALE body OR region DISTRIBUTION or segment (Figure 4.21). Each Homeobox, or Hox, genes. These genes control the Hox gene or cluster of genes has been given a name. early development of certain body regions into par- For example, the protein Sonic Hedgehog (named after ticular segments or structures (Figure 4.21). Hox genes one worker’s favorite video game character) stimulates © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC

NOT(a) Drosophila FOR SALE embryo OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Head Thorax Abdomen

NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTIONx A B s a l l d b a a e m d in in l rm bithor ia co ce om om p (b) o x u ra u ab ef d lt bd roup bd ro L Proboscipedia D Se re AntennapediaU A g A g Drosophila HOM-C © JonesAmphioxus & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FORHox SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Mouse Hox-B Human Hox-B © Jones & Bartlett Learning,Tr ibolium LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR HOM-CDISTRIBUTION NOT FOR SALE OR DISTRIBUTION Caenorhabditis HX-C

NOT FOR SALE OR DISTRIBUTION 1st NOT2nd FOR3rd SALE4th–7th OR DISTRIBUTION arch arch arch arches

Mouse embryo Hindbrain © Jones & Bartlett Learning, LLC6 78 © Jones & Bartlett Learning, LLC 1 2 3 4 5 NOT FORMidbrain SALE OR DISTRIBUTION NOTHox b6FOR SALE OR DISTRIBUTION Hox b5 Hox b4 Forebrain Hox b3 Hox b2 © Jones & Bartlett Learning, LLC © Jones & BartlettHox b1 Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALEHox OR a1 DISTRIBUTION Hox a2 Hox a3 Hox a4 Hox a5 Figure 4.21 (a) The distribution of Hox genes in the fruit flyDrosophila . (b, c) Note the similarity of the Hox genes in Drosophila © Jones & Bartlettto those of Learning, other widely differing LLC taxa, including arthropods (Tribolium© Jones), worms & Bartlett (Caenorhabditis Learning,), and the mouse.LLC Forms similar to NOT FOR SALEAmphioxus OR areDISTRIBUTION thought to have given rise to vertebrates. NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. the formation and secretion of a growth-stimulating embryonic development different Hox genes are “turned © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC protein during early embryonic development of ver- on” and “turned off” by positive and negative feedback. NOT FORtebrate SALE limbs. OR DISTRIBUTIONIncreasingly, however, Hox genes are NOTProteins FOR codedSALE by OR certain DISTRIBUTION regions of DNA affect the for- referred to as “Hox 1,” “Hox 2,” and so on for the sake mation of different types of tissues and organs at spe- of clarity. Some Hox genes establish the anterior (front) cific locations during development. The differentiation to posterior (tail) axis of the animal or the dorsal (top) of cells into tissues and organs may in turn trigger the to ventral (bottom) orientation© Jones of &the Bartlett body. Other Learning, Hox activationLLC of other DNA sites© for Jones transcription & Bartlett and so Learning, LLC genes code for the initialNOT subdivision FOR SALE of the OR body DISTRIBUTION into on in a kind of developmentalNOT cascade FOR (Figure SALE 4.22 OR). DISTRIBUTION segments and still others for limb generation, the fate Indeed, certain DNA sequences are referred of muscles, and light receptors such as eyes. to as master control genes. Master control genes are Hox genes themselves have been duplicated like the master switch on the electric service panel in a and modified in different groups through time. As its house that controls all the circuit breakers. The circuit © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC name implies, the gene Antennapedia codes for anten- breakers are analogous to genes that code for enzymes nae andNOT legs FOR in the SALE anterior OR region DISTRIBUTION of the fruit fly. In in different metabolicNOT FOR pathways. SALE If OR a circuit DISTRIBUTION breaker is mice and humans this gene has been duplicated four flipped from the “on” to the “off” position, electricity times, but it is still involved in the differentiation of will not flow through the circuits it controls, and the the head region. Another example of gene duplication lights will not come on in certain parts of the house or © Jones &is theBartlett long row Learning, of vertebrae LLC in extinct marine reptiles © Jonesthe washing & Bartlett machine Learning, won’t wash, LLCfor example. How- NOT FORsuch SALE as plesiosaurs OR DISTRIBUTION and land-dwelling sauropods (see NOTever, FOR all otherSALE circuits OR DISTRIBUTIONto the rest of the house remain Chapter 13). Because identical or nearly identical Hox unaffected. But if the master switch is thrown, all circuit genes have been found in a variety of creatures rang- breakers and circuits are inactivated because the flow ing from worms to insects to vertebrates (based on of electricity into the entire house has been completely sequences of DNA nucleotides), these genes must have shut off. The same is true of master control genes, been present early in evolution© Jones and & passedBartlett on inLearning, sub- whichLLC control the DNA transcription© Jones of &a numberBartlett of Learning, LLC sequent lineages throughNOT time. FOR In fact, SALE approximately OR DISTRIBUTION genes and metabolic pathwaysNOT “downstream”. FOR SALE OR DISTRIBUTION 99% of the genes in chimpanzees and humans are If a mutation occurs in a Hox gene or another identical; the two species differ primarily because of gene that is involved in early development, it may cause the regulatory genes expressed during development. a cascade of genetic and developmental changes that affect all the other genetic pathways downstream. Nor- © JonesExperiments & Bartlett have been Learning, conducted in LLC which the © Jones & Bartlett Learning, LLC Antennapedia gene of the fruit fly (an insect widely used mally, mutations that occur early during the embryonic in laboratoryNOT FOR genetic SALE experiments) OR DISTRIBUTION was transplanted into developmentNOT of an organismFOR SALE are lethal OR because DISTRIBUTION embry- worms with a mutant form of the Antennapedia gene. onic development is a tightly controlled process. Early After transplantation the worm’s offspring developed development tends to “lock in” later developmental normally. These sorts of experiments indicate that during pathways, such as the differentiation of new tissues © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION MasterNOT control FOR gene SALE OR DISTRIBUTION

Master control gene

(b) Mutation in developmental pathway © Jones &Figure Bartlett 4.22 eLearning,ffects of mutations LLC in genetic cascades. (a) Normal© Jones developmental & Bartlett pathway. Learning, (b) A mutation LLC in a developmental NOT FORpathway SALE affects OR laterDISTRIBUTION developmental pathways controlled by theNOT DNA inFOR which SALE the mutation OR occurs.DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. and organs and their positions in the embryo. But if A mechanism of rapid evolutionary change © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC important genetic changes occur that affect early devel- also related to changes in developmental pathways NOT FOR SALEopment OR and DISTRIBUTION the changes are nonlethal, they can affectNOT FORis preadaptation SALE OR orDISTRIBUTION “latent potential.” Preadaptation subsequent gene expression and biochemical pathways refers to the existence of a structure adapted for a par- further along in development (Figure 4.22). These sorts ticular function or environmental condition that turns of changes explain anatomic similarities such as ho- out by chance to be adapted for rapid evolution into a mologous structures© Jones (Figure 4.13).& Bartlett Learning, LLCdifferent niche (Figure 4.23© Jones). How, &for Bartlett example, Learning,can LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Skull

Pelvic Pectoral girdle girdle © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION(a) Eusthenopteron NOT FOR SALE OR DISTRIBUTION

(b) Ichthyostega © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Structures that appear NOT FOR SALERhipidistian OR DISTRIBUTION fish to be homologousNOT FOR LabyrinthodontSALE OR amphibian DISTRIBUTION (Panderichthys) (Ichthyostega) Internasal Pre-maxillary Nasal Septomaxillary © Jones & Bartlett Learning, LLC © JonesPre-frontal & Bartlett Learning, LLC Frontal NOT FOR SALE OR DISTRIBUTION NOT FORLacrimal SALE OR DISTRIBUTION Optic orbit Supraorbital Jugal Pineal foramen Post-orbital © Jones & Bartlett Learning, LLCParietal © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTIONSupratemporal NOT FOR SALE OR DISTRIBUTION Squamosal Temporal Post-parietal Opercular Pre-opercular © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION (c) Figure 4.23 Preadaption in ancient lobe-finned fish and primitive amphibians. (a) Eusthenopteron, a primitive lobe-finned fish. [Adapted from: Romer, A. S. and Parsons, T. S. 1977. The Vertebrate Body, 5th ed. Philadelphia: W. B. Saunders]. (b) Ichthyostega, a primitive labyrinthodont or temnospondyl. (c) Comparison of skull structure of a primitive lobe-finned fish and temnospondyl. © Jones & Bartlett[Adapted from:Learning, Duellman, LLCW. E. and Trueb, L. 1986. Biology© of JonesAmphibians &, Bartlett1st ed. New Learning, York: McGraw-Hill; LLC Part 2 adapted from: NOT FOR SALECoates, OR M. I. DISTRIBUTIONand Clack, J. A. 1990. Polydactyly and the earliestNOT known FOR tetrapod SALE limbs. OR Nature DISTRIBUTION 347, 66–69.]

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. an eye or a wing evolve through intermediate stages to “species selection.” This upset some evolutionists, © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC its final form? Wouldn’t intermediate stages of a struc- who objected to the implication that the mechanism NOT FOR SALE OR DISTRIBUTION NOT FORture SALE put creatures OR DISTRIBUTION at such a selective disadvantage they of natural selection, as applied to populations, could be would be culled by natural selection almost instantly? applied to species or higher taxa. In fact, species sorting This question had long plagued evolutionary biologists, has nothing to do directly with natural selection; rather, including Darwin. it is envisioned to act more like pruning a bush. Some Since Darwin’s© Jonestime a number & Bartlett of examples Learning, speciesLLC are more likely to leave© moreJones “offspring” & Bartlett (new Learning, LLC of preadaptation haveNOT been FOR documented. SALE OR Primitive DISTRIBUTION species) than others so thereNOT are differential FOR SALE “births” OR DISTRIBUTION light-sensing and temperature-regulating organs were and “deaths” of species. preadapted to give rise to eyes and wings, respectively, in arthropods. In experimental studies of insects, small wings are used to regulate body temperature; Concept and Reasoning Checks © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC as the wings increase in size, the advantages for flight NOT FOR SALE OR DISTRIBUTION 1. Both microevolutionNOT FOR SALE and ORmacroevolution DISTRIBUTION become dominant just as the benefits of wings for involve mutation. How, then, do the processes body temperature regulation begin to level off. As of macroevolution differ from those of micro- demonstrated by the fossil record, the stubby limbs of evolution? primitive lobe-finned fish (related to the coelacanth) 2. What is the importance of preadaptation to © Jones &may Bartlett have helped Learning, them scoot LLC along shallow bottoms, © Jonesmacro & Bartlettevolution? Learning, LLC NOT FORbut SALE the limbs OR wereDISTRIBUTION preadapted for a rapid transition NOT FOR SALE OR DISTRIBUTION to land by primitive amphibians called labyrintho- donts (now called “temnospondyls”; Figure 4.23). Based on the striking similarity of bone structure in these two groups, relatively small changes in develop- © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC mental pathways could easily have transformed the Mass Extinction NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION lobe-finned limb into that of a primitive amphibian; 4.10 Extinction is normal and has occurred as described above, the genetic changes could have through geologic time as a kind of background ex- spread rapidly through relatively small, isolated tinction. Despite all their adaptations produced in populations along the shore. In fact, the limb bone response to natural selection, most taxa have become structure© Jones of both & groupsBartlett has Learning, long been considered LLC extinct. In fact,© Jones the fossil & recordBartlett indicates Learning, that more LLC homologous.NOT FOR SALE OR DISTRIBUTION than 99.9% NOTof all speciesFOR SALEthat have OR ever DISTRIBUTION existed have Darwin was also aware of the existence of vesti- become extinct. Many taxa died out when the bio- gial structures in a wide range of animals (Figure 4.24). sphere was decimated during mass extinctions. As As the term indicates, vestigial structures are vestiges we will see in later chapters, mass extinctions have of organs or structures that previously performed a © Jones & Bartlett Learning, LLC © Jonesresulted & fromBartlett different Learning, causes, amongLLC them global particular function but that later degenerated and now cooling, massive volcanism, decreased oxygen in the NOT FORhave SALE little OR or noDISTRIBUTION use; the appendix of humans and NOToceans, FOR and SALE meteor OR impacts. DISTRIBUTION dewclaws of dogs are examples (Figure 4.24). On the Despite the negative consequences for the surface vestigial structures also posed the problem of biosphere, mass extinction is exceedingly important intermediate stages in evolution. However, rather than to biologic evolution. Mass extinction may have been being preadapted for ©future Jones use (as& Bartletta teleologic Learning, view necessary LLC to increase Earth’s biodiversity,© Jones & for Bartlett without Learning, LLC of evolution would demand),NOT FOR vestigial SALE structures OR DISTRIBUTION were extinction far fewer evolutionaryNOT opportunities FOR SALE would OR DISTRIBUTION just the opposite: they were a waste of energy to pro- have occurred because all the habitats and niches duce and were being selected against, according to would otherwise have been filled long ago. Extinction, Darwin’s theory. Thus, vestigial structures argue for then, is a mechanism of macroevolutionary change natural selection and evolution, not against it. © Jones & Bartlett Learning, LLC that might not© Jonesotherwise & occur. Bartlett Thus, Learning, mass extinction LLC Another example of macroevolution may be produces history by altering the course of life. long-termNOT patterns FOR SALE of species’ OR appearances DISTRIBUTION and extinc- TheNOT phenomenon FOR SALE by ORwhich DISTRIBUTION new species tions in the fossil record called species sorting. In theory, fill the niches of previously existing species after mass species sorting resembles punctuated equilibria, but extinction is called ecologic replacement. The process instead of individuals being selected against, natural of ecologic replacement can be envisaged as a theater © Jones &selection Bartlett acts Learning, to weed out LLC whole species. Unfortu- © Jonesin which & the Bartlett “stage” (planet Learning, Earth) LLChas existed through NOT FORnately, SALE species OR DISTRIBUTION sorting was originally referred to as NOTtime FOR but SALEon which OR the DISTRIBUTION “actors” (taxa) have changed

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Pelvis

Femur Whale © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Termination Rudimentary of hind limbs hind limbs © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION IIium

Femur © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

llukS sivleP enitsetnI © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Rudimentary ear muscles Coccygeal tail vertebrae Third molars (wisdom teeth) © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Vermiform appendix Figure 4.24 examples of vestigial structures. [Part 1 modified from: Romanes, G. J. 1910. Darwin, and After Darwin, 1st ed. Chicago: The Open Court Publishing Company.] © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. through time because of changes to the stage or physical is constrained by a kind of founder effect but on a © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC environment of Earth. A prime example is the extinc- much more massive scale. Many new classes, orders, NOT FOR SALE OR DISTRIBUTION NOT FORtion SALE of dinosaurs OR DISTRIBUTION at the end of the Cretaceous Period, families, genera, and species may certainly evolve which allowed the evolutionary diversification of mam- after an extinction—especially a mass extinction—but mals, leading eventually to humans. When massive no new phyla appear because the basic body plans ecologic replacement (such as that of the dinosaurs by (groundplans) of phyla remained the same. These the mammals) or diversification© Jones (for& Bartlett whatever Learning,reason) geneticallyLLC based groundplans© served Jones as the & foundation Bartlett Learning, LLC occurs among a particularNOT taxon, FOR it SALE is referred OR to DISTRIBUTION as an on which the new taxa are reconstructed.NOT FOR In otherSALE words OR DISTRIBUTION adaptive radiation. evolution occurred within phyla, but wholly new phyla All mass extinctions seem to have some com- or groundplans did not appear. mon features. First, the survival of species depends on their ©tolerance Jones to & environmental Bartlett Learning, change. LLCEurytopic © Jones & Bartlett Learning, LLC species are more likely to survive than stenotopic ones Concept and Reasoning Check NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION because eurytopic taxa are tolerant of environmental 1. How does the genetic composition of a species change and are more likely to be widespread, increas- influence its evolutionary potential? ing their chances of survival in refuges (Chapter 2). Eurytopic taxa are also much more variable geneti- © Jones &cally Bartlett than stenotopic Learning, taxa; LLC if this were not the case © Jones & Bartlett Learning, LLC NOT FOReurytopic SALE OR taxa DISTRIBUTION would not be as tolerant of environ- NOT FOR SALE OR DISTRIBUTION mental change and would not be as widely distributed. Thus, once extinction has ceased, eurytopic taxa 4.11 Biodiversity Through rapidly evolve new adaptations as they radiate into the Phanerozoic the habitats and niches© Jonesleft vacant & byBartlett the extinction Learning, SoLLC far we have examined evolution© Jones at the & microBartlett and Learning, LLC of previously existing taxa. NOT FOR SALE OR DISTRIBUTIONmacro levels with regard to NOTthe appearance FOR SALE of new OR DISTRIBUTION Second, after extinction (called the recovery species and new higher taxa and their extinction. But phase), any and all mechanisms of microevolution how have some of these changes played out during and macroevolution may give rise to new taxa through the broad evolution of the biosphere through the adaptive radiation. However, extinction does not mean Phanerozoic Eon? that “anything© Jones goes” & Bartlett as the biosphere Learning, recovers LLC and new The© fossil Jones record & Bartlettreflects Learning,major changes LLC in taxa NOTevolve. FOR In fact, SALE the founding OR DISTRIBUTION taxa are subject to the evolutionNOT of marine FOR andSALE terrestrial OR DISTRIBUTION communities similar natural selection pressures and limitations through the Phanerozoic (Figure 4.26). Fossils first of genetic constraints as their ancestors. This is evi- became abundant in the marine geologic record about denced by the phenomenon of convergent evolution 540 million years ago at the beginning of the Cam- between taxa belonging to widely different evolu- © Jones & Bartlett Learning, LLC © Jonesbrian Period. & Bartlett These fossilsLearning, belong LLCto the evolutionary tionary lineages to produce analogous structures or NOT FOR SALE OR DISTRIBUTION NOTfauna FOR called SALE the CambrianOR DISTRIBUTION Fauna. The communities features (Figure 4.14). A similar phenomenon known of the Cambrian Fauna appear primitive compared as iterative evolution occurs within the same taxa that with those of later times and were dominated by taxa are more closely related by evolution. For example, at such as trilobites and jawless fish that fed very close different times during Earth’s history both a mass to the sediment surface or just beneath it. extinction and a smaller© Jonesminor extinction & Bartlett decimated Learning, LLC The Paleozoic Fauna ©began Jones to diversify & Bartlett during Learning, LLC planktonic organismsNOT called FOR foraminifera. SALE AfterOR DISTRIBUTION each the Ordovician Period, beginningNOT about FOR 500 SALE million OR DISTRIBUTION of these extinctions, new species of foraminifera years ago, as the Cambrian Fauna began to wane evolved that closely resembled the taxa that lived (Figure 4.26). The Paleozoic Fauna was much more before each extinction (Figure 4.25). diverse than the Cambrian Fauna and was dominated Thus, the fossil record indicates that the evo- © Jones & Bartlett Learning, LLC by suspension-feeding© Jones taxa & Bartlettthat fed on Learning, suspended LLCor- lution of new taxa after extinction is constrained by the ganic matter and plankton above bottom, including “geneticNOT baggage” FOR SALEof the surviving OR DISTRIBUTION taxa. Surviving taxa corals and coral-likeNOT FOR taxa. SALE In fact, OR one DISTRIBUTION of the most serve as the ancestors of the taxa that diversify during significant developments of the Silurian and Devonian the recovery phase. Thus, certain genetic programming was the appearance of widespread reefs. Jawed preda- is already “hard-wired” into the founding taxa and tors such as sharks that were capable of crushing the © Jones &constrains Bartlett the Learning, evolution of LLC new traits. In other words © Joneshard shells & Bartlett of prey or Learning, feeding on fishLLC became promi- NOT FORthe SALE evolution OR ofDISTRIBUTION new taxa during the recovery phase NOTnent FOR by theSALE end ofOR the DISTRIBUTION Devonian and Early Carbon-

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Paleogene Adaptive Radiation

Orbuline © JonesGlobigerinoid & Bartlett Learning, Hastigerine LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Figure 4.25 Iterative evolution is like convergent evolution (Figure 4.14) but occurs among closely related taxa, such as the species of planktonic foraminifera shown here. [Adapted from: Prothero, D. R. 1998. Bringing Fossils to Life. WCB/McGraw Hill. Boston, MA, Figure 11.9B (p. 197).] © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. Geologic time © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC 550 500 450 400 350 300 250 200 150 100 050 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 800 1750 750 700 650 © Jones & Bartlett Learning, LLC Modern© Jones & Bartlett Learning, LLC 600 NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 550 500 Paleozoic 450 400 © Jones350 & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR300 SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Number of families 250 Cambrian 200 150 100 © Jones & Bartlett Learning,50 LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION0 NOT FOR SALE OR DISTRIBUTION

Cambrian Ordovician Silurian Devonian Carboniferous Permian Triassic Jurassic Cretaceous Cenozoic

© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Figure 4.26 the major changes in marine faunas of the Phanerozoic. [Adapted from: Sepkoski, J. J., Jr. 1981. A factor analytic description of the PhanerozoicNOT marine FOR fossil SALE record. ORPaleobiology DISTRIBUTION 7, 36–53.] NOT FOR SALE OR DISTRIBUTION

iferous periods. It therefore appears that marine food becoming prominent in the fossil record. One of the chains were lengthening and food webs becoming most significant developments in the marine realm more© complex Jones during & Bartlett the Paleozoic. Learning, The lengthening LLC was the great© evolutionaryJones & Bartlett expansion Learning, of predatory LLC of theNOT food FORchains SALE suggests OR increasing DISTRIBUTION food (energy) gastropods (snails),NOT FOR more SALE modern OR fish, DISTRIBUTION and large ma- availability at the base of food pyramids that could rine reptiles, again suggesting increased food avail- be passed upward to support the predators, which ability and metabolism. On land, terrestrial forests likely had elevated metabolism for locomotion and continued to expand during the Mesozoic (Figure predation. Food webs also became more complex 4.26). Roaming these forests were the dinosaurs, © Jones &on Bartlett land. The Learning, spread of forests LLC into the interiors of © Joneswhereas & theBartlett seas were Learning, prowled LLCby whale-like and NOT FORcontinents SALE OR led DISTRIBUTIONto the widespread coal-forming forests NOTdolphin-like FOR SALE reptiles. OR DISTRIBUTION Flowering plants blossomed of the Carboniferous Period. These forests provided during the Cenozoic Era, whereas the dinosaurs were habitats and niches for the evolutionary diversifica- replaced by the mammals on both land and in the tion of insects, amphibians, and eventually reptiles. seas after yet another mass extinction at the end of The Paleozoic Fauna suffered a number of minor ex- the Cretaceous Period. tinctions and two mass© extinctionsJones & Bartlett at the end Learning, of the LLC Thus, biodiversity appears© Jones to have & Bartlettincreased Learning, LLC Ordovician and DevonianNOT periods FOR thatSALE contributed OR DISTRIBUTION to through the Phanerozoic. ButNOT questions FOR remain. SALE Why, OR DISTRIBUTION evolutionary turnover through the Paleozoic. Never- for example, did the Paleozoic Fauna maintain a rela- theless, the Paleozoic Fauna remained recognizable tively stable level of biodiversity? No one knows. And to the end of the Paleozoic Era. is the steep increase in diversity of the Modern Fauna © JonesThe Paleozoic & Bartlett Fauna wasLearning, replaced by LLC the Mod- real or is it ©an Jonesartifact of& theBartlett fossil record,Learning, or both? LLC ern FaunaNOT inFOR the Triassic SALE Period OR DISTRIBUTION after the greatest mass These are amongNOT FORthe most SALE fundamental OR DISTRIBUTION questions extinction in Earth’ history about 250 million years ago confronting Earth scientists today. As we will see in (Figure 4.26). As its name implies, the Modern Fauna Chapter 5, younger rocks and their fossils (like those was much more like the faunas we see today. Still, the of the Mesozoic and Cenozoic eras) are more likely to biotas of the Modern Fauna also changed through time. be found at Earth’s surface than much older ones (like © Jones &Marine Bartlett plankton Learning, underwent LLC a tremendous diversifica- © Jonesthose of & the Bartlett Paleozoic) Learning, because there LLC has been less time NOT FORtion, SALE with OR coccolithophorids DISTRIBUTION and ultimately diatoms NOTfor FOR younger SALE rocks OR to be DISTRIBUTION eroded.

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. and behavior of chromosomes during cell © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC Concept and Reasoning Checks division. Eventually, it was found that NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 1. Do you suppose all the processes involved in evolu- genetic variation is produced by mutation, tion are observable or can be inferred from labora- coupled with the formation of gametes tory experiments? Why or why not? and sexual reproduction. Eventually, 2. What does the succession of major faunas the genetic material was determined to through time© indicate Jones about& Bartlett directionality Learning, of LLC be DNA. © Jones & Bartlett Learning, LLC Earth’s historyNOT (see FORChapter SALE 1)? OR DISTRIBUTIONn New species typicallyNOT arise FOR through SALE allo OR- DISTRIBUTION patric speciation. In allopatric speciation natural selection acts on demes or peripheral isolates, which evolve through the © Jones & Bartlett Learning, LLC accumulation© Jones & Bartlettof mutations, Learning, genetic drift,LLC NOT FOR Summary SALE OR DISTRIBUTION andNOT the FOR founder SALE effect. OR DISTRIBUTION 4.12 n In the fossil record new species may appear n Charles Darwin’s theory of evolution gradually through the process known as irrevocably changed the view of Earth phyletic gradualism or through the process known as punctuated equilibrium. Once they © Jones & Bartlett fromLearning, one of equilibrium LLC to one of direc- © Jones & Bartlett Learning, LLC tionality and history. Darwin’s theory has have appeared, new species may be sorted. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION remained largely intact to the present. n Rapid evolution of new structures and n Darwin reasoned that new species evolve possibly whole new taxa may take place based on the following simple observa- through mutations in master control or tions and inferences: the great diversity Hox genes that affect developmental of plants ©and Jones animals & andBartlett their variation, Learning, LLC pathways. © Jones & Bartlett Learning, LLC their geographicNOT FOR distributions, SALE OR and DISTRIBUTION the n Although the exactNOT causes FOR of extinctionSALE OR DISTRIBUTION fact that natural populations do not grow vary, extinction can also be considered as an unchecked. agent of macroevolution because it opens up n Therefore, he reasoned, there must be a many habitats and niches simultaneously. struggle for existence that eliminates unfit Eurytopic species are more likely to survive © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC individuals. Based on breeders’ experiments extinction than stenotopic ones because NOT FORwith agriculturalSALE OR stocks, DISTRIBUTION Darwin reasoned NOTeurytopic FOR taxa SALE are tolerant OR DISTRIBUTION of environmen- the traits of those individuals that survive tal change and are more likely to be wide- and reproduce are passed on to their off- spread, increasing their chances of survival spring (differential reproduction), so there in refuges. © Jones & Bartlett isLearning, descent with LLC modification. Thus, there © Jones &n BartlettEurytopic Learning, taxa are also LLC much more vari- NOT FOR SALE ORis aDISTRIBUTION naturally occurring selection for fitterNOT FOR SALEable ORgenetically DISTRIBUTION than stenotopic taxa, so individuals. that once extinction has ceased, eurytopic n Experiments by Gregor Mendel demon- taxa rapidly evolve new adaptations as strated that genetic traits were passed they radiate into the habitats and niches from parents to offspring. Later, these left vacant by the extinction of previously © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC traits were correlated with the appearance existing taxa. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones &Sources Bartlett andLearning, Further LLC Reading © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Albritton, C. C. 1980. The abyss of time: Changing con- Martin, R.E. 1996. Secular increase in nutrient levels ceptions of the earth’s antiquity after the sixteenth through the Phanerozoic: implications for pro- century. San Francisco: W. H. Freeman. ductivity, biomass and diversity of the marine Bambach, R. K. 1933.© SeafoodJones through& Bartlett time: Learning,chang- LLCbiosphere. Palaios, 11, 209-219.© Jones Henig, & Bartlett R. M. Learning, LLC es in biomass, NOTenergetics, FOR and SALE productivity OR DISTRIBUTION in 2000. The monk in the garden:NOT The FOR lost and SALE found OR DISTRIBUTION the marine ecosystem. Paleobiology, 19, 372-397. genius of Gregor Mendel, the father of genetics. Bos- Bambach, R.K. 1999. Energetics in the global marine ton: Houghton Mifflin. fauna: a connection between terrestrial diver- Raff, R. 1996. The shape of life. Chicago: University ©sification Jones &and Bartlett change inLearning, the marine LLCbiosphere. of Chicago© JonesPress. & Bartlett Learning, LLC NOTGeoBios, FOR 32, SALE 131-144. OR DISTRIBUTION Schwartz, J. H.NOT 1999. FOR Sudden SALE origins: OR Fossils, DISTRIBUTION genes, and Bowler, P. J. 1989. Evolution: The history of an idea. the emergence of species. New York: John Wiley Berkeley, CA: University of California Press. & Sons. Carroll, S. B. 2005. Endless forms most beautiful: The Schwartz, J. 2008. In pursuit of the gene, Cambridge, new science of evo devo and the making of the animal MA: Harvard University Press. © Jones & Bartlettkingdom. Learning, New York: LLCW. W. Norton. © JonesShermer, & M.Bartlett 2002. In Learning, Darwin’s shadow: LLC The life and NOT FOR SALEDesmond, OR A. DISTRIBUTION and Moore, J. 1991. Darwin: The life of a NOT FORscience SALE of Alfred OR Russell DISTRIBUTION Wallace. A biographical tormented evolutionist. New York: Warner Books. study on the psychology of history. Oxford, UK: Eldredge, N. 1995. Reinventing Darwin: The great Oxford University Press. debate at the high table of evolutionary theory. New Vendetti, C., Meade, A., and Pagel, M. 2010. Phylog- York: John Wiley© &Jones Sons. & Bartlett Learning, LLCenies reveal new interpretation© Jones of speciation & Bartlett and Learning, LLC Henig, R. M. 2000.NOT The monk FOR in theSALE garden: OR The DISTRIBUTION lost the Red Queen. Nature, 463,NOT 349–352. FOR SALE OR DISTRIBUTION and found genius of Gregor Mendel, the father of Wallace, B. 1992. The search for the gene. Ithaca, NY: genetics. Boston: Houghton Mifflin. Cornell University Press. Hannisdal, B. and Peters, S. E. 2011. Phanerozoic Watson, J. 1968. The double helix. New York: Signet. Earth system evolution and marine biodiversity. Zimmer, C. 1998. At the water’s edge: Macroevolu- ©Science Jones, 334, & Bartlett1121–1124. Learning, LLC tion and the© Jonestransformation & Bartlett of life. New Learning, York: The LLC Katz,NOT M. FORE., Wright, SALE J. ORD., Miller,DISTRIBUTION K. G., Cramer, Free Press.NOT FOR SALE OR DISTRIBUTION B. S., and Fennel, K. 2005. Biological overprint of the geological carbon cycle. Marine Geology, 217, 323-338. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

Key Terms © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION acquired characteristics, theory of inheritance of clade, versus grade adaptive radiation cladistics: cladograms, primitive traits, derived traits allopatric speciation extinction, and recovery phase analogous© Jones structures, & Bartlett versus Learning, homologous LLC structures deme (peripheral© Jones isolate) & Bartlett Learning, LLC background extinction descent with modification binomialNOT FOR nomenclature SALE OR DISTRIBUTION differential reproductionNOT FOR SALE OR DISTRIBUTION biogenetic law ecologic replacement biologic classification (taxonomy) enzyme (active site) Central Dogma: transcription, translation eugenics © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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© Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. © Jones & BartlettKey Terms Learning, (continued LLC ) © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION evolution, patterns of (convergent, divergent, macroevolution, mechanisms of (Hox genes, pre- iterative) adaptation, species sorting, extinction) evolutionary fauna: Cambrian, Paleozoic, Modern mass extinctions extinction: background,© Jones mass, & Bartlett minor Learning, LLCminor extinction © Jones & Bartlett Learning, LLC founder effect NOT FOR SALE OR DISTRIBUTIONmissing link NOT FOR SALE OR DISTRIBUTION gene, master control natural selection, balancing versus directional genetic drift neo-Darwinism genetic engineering ontogeny, versus phylogeny ©genetic Jones recombination & Bartlett Learning, LLC phyletic© gradualism, Jones & versus Bartlett punctuated Learning, equilibrium LLC NOTgroundplans FOR SALE OR DISTRIBUTION protein NOT FOR SALE OR DISTRIBUTION homeobox (Hox) genes pseudoextinction hybrid vigor reproductive isolation industrial melanism sexual selection inheritance, theories of: acquired characteristics, social Darwinism © Jones & Bartlettblending, Learning, particulate LLC © Jonesspeciation, & Bartlett allopatric Learning, LLC NOT FOR SALElabyrinthodonts, OR DISTRIBUTION and lobe-finned fish NOT FORspecies SALE OR DISTRIBUTION living fossil subspecies, and races macroevolution, versus microevolution vestigial structures

1. What are the basic observations that led to 12. Distinguish between monophyletic, polyphy- Darwin’s theory of evolution? letic, and paraphyletic. Are paraphyletic taxa © Jones2. Give &any Bartlett modern Learning, and ancient LLC examples for polyphyletic?© Jones & Bartlett Learning, LLC NOT (a)FOR natural SALE selection OR DISTRIBUTION and (b) evolution. 13. WhatNOT are theFOR processes SALE involvedOR DISTRIBUTION in (a) micro- 3. What was the significance of Mendel’s discoveries? evolution? (b) macroevolution? 4. Diagram the replication, transcription, and 14. What is a living fossil and what does it represent translation of DNA. in terms of punctuated equilibrium? © Jones & Bartlett 5. Diagram Learning, the Central LLC Dogma of cell biology.© Jones 15. & Why Bartlett is preadaptation Learning, important LLC for evolution? How does a mutation affect the kinds of pro- Give examples. NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION teins produced? 16. At what taxonomic categories do microevolu- 6. How does a mutation affect the active site of an tion and macroevolution act? Where might they enzyme? overlap? 7. What is involved in genetic recombination? 17. Using diagrams, show how allopatric speciation 8. What is the© difference Jones between& Bartlett the terms Learning, natural LLC is related to the pattern© Jones of punctuated & Bartlett equilib Learning,- LLC selection, founderNOT FOR effect, SALE and genetic OR DISTRIBUTION drift? rium seen in the fossilNOT record. FOR SALE OR DISTRIBUTION 9. Arrange the following in order (first to last): 18. What pattern(s) do microevolution and macro- geographic isolation, allopatric speciation, repro- evolution generate in the fossil record? ductive isolation. How does one give rise to 19. Contrast natural selection with species sorting. © Jonesthe next? & Bartlett Learning, LLC 20. Why© areJones missing & linksBartlett rare? Learning, LLC 10. How can races and subspecies lead to the pro- 21. What is the role of extinction in evolution? NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION duction of new species? 22. List as many examples of natural selection as 11. Construct a simple, hypothetical set of taxa with you can that were discussed in this chapter. a few characteristics and then draw a cladogram for them. © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION

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1. Do you believe evolution is teleologic? 6. Does science work in a cultural and political 2. Compare the concept of species as defined by vacuum? biologic criteria with a species as it is recognized 7. What differentiates mass, minor, and background in the fossil record.© Jones How &do Bartlettthey differ? Learning, How LLCextinction? © Jones & Bartlett Learning, LLC are they similar?NOT Why FOR are they SALE similar? OR DISTRIBUTION 8. Comment on the role of NOTcausality FOR in extinction SALE OR DISTRIBUTION 3. Exactly what is “success” in terms of natural (look ahead to chapters 11, 12, and 13). selection? 9. What is the role of contingency (Chapter 1) in 4. What is the difference between a preadapted extinction? ©structure Jones and& Bartlett a vestigial Learning, structure? How LLC do both 10. Why is important© Jones to & find Bartlett out if Learning,the increase LLCof NOTargue FOR for evolution? SALE OR Give DISTRIBUTION examples. fossil biodiversityNOT FOR is realSALE or not? OR DISTRIBUTION 5. Can one oppose the theory of evolution without opposing the scientific method?

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©The Jones Grand Canyon.& Bartlett The Colorado Learning, River cut LLCthe © Jones & Bartlett Learning, LLC canyon in only about 10 million years after uplift NOTof the FORColorado SALE Plateau. OR The rocksDISTRIBUTION exposed NOT FOR SALE OR DISTRIBUTION along the sides of the canyon range in age from Precambrian to Permian.