1 Life: Biological Principles and theScience of Zoology 22 The Origin and Chemistry of Life22 3 Cells as Units of Life 38 10 Classification and Phylogeny ofAnimals 196... CHAPTER 3 Cells
Trang 2INTEGRATED PRINCIPLES OF
Trang 3ALLAN LARSON Washington University
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Trang 51 Life: Biological Principles and theScience of Zoology 2
2 The Origin and Chemistry of Life22
3 Cells as Units of Life 38
10 Classification and Phylogeny ofAnimals 196
Trang 6CHAPTER 3 Cells as Units of Life 38
Cell Concept 39 Organization of Cells 41 Mitosis and Cell Division 51 Summary 56
CHAPTER 4 Cellular Metabolism 58
Energy and the Laws of
Thermodynamics 59 The Role of Enzymes 59 Chemical Energy Transfer by ATP 62 Cellular Respiration 63
Metabolism of Lipids 70 Metabolism of Proteins 71 Management of Metabolism 72 Summary 73
CHAPTER 5
Principles of Genetics:
Mendel’s Investigations 77 Chromosomal Basis of Inheritance 78 Mendelian Laws of Inheritance 81 Gene Theory 89
Storage and Transfer of Genetic
Information 90 Sources of Phenotypic Variation 99 Molecular Genetics of Cancer 100 Summary 101
CHAPTER 6
Organic Evolution 104
Origins of Darwinian Evolutionary
Theory 105 Darwinian Evolutionary Theory: The
Evidence 109 Revisions of Darwin’s Theory 123 Microevolution: Genetic Variation and
Change within Species 124 Macroevolution: Major Evolutionary
Events 129 Summary 132
CHAPTER 7
The Reproductive Process 135
Nature of the Reproductive Process
136 The Origin and Maturation of Germ
Cells 140 Reproductive Patterns 144 Plan of Reproductive Systems 144 Endocrine Events That Orchestrate
Reproduction 147 Summary 154
CHAPTER 8
Principles of Development 156
Early Concepts: Preformation Versus
Epigenesis 157 Fertilization 158
CHAPTER 1 Life: Biological Principles and the Science of Zoology 2
Fundamental Properties of Life 3 Zoology as a Part of Biology 11 Principles of Science 11
Theories of Evolution and Heredity 13 Summary 20
CHAPTER 2 The Origin and Chemistry
of Life 22
Organic Molecular Structure of Living
Systems 23 Chemical Evolution 27 Origin of Living Systems 31 Precambrian Life 33 Summary 35
PART TWO
CONTINUITY AND EVOLUTION OF ANIMAL LIFE
Trang 7Major Divisions of Life 207 Major Subdivisions of the Animal
Kingdom 208 Summary 211
CHAPTER 11
Form and Function 215 Representative Types 223 Phylogeny and Adaptive Radiation
235 Summary 238
CHAPTER 12
Origin of Metazoa 241 Phylum Mesozoa 242 Phylum Placozoa 243 Phylum Porifera: Sponges 243 Summary 251
CHAPTER 13 Radiate Animals 253
Phylum Cnidaria 254 Phylum Ctenophora 274 Phylogeny and Adaptive Radiation
277 Summary 279
CHAPTER 14
Phylum Platyhelminthes 282 Phylum Nemertea (Rhynchocoela) 297 Phylum Gnathostomulida 299
Phylogeny and Adaptive Radiation
300 Summary 302
CHAPTER 15
Pseudocoelomates 305 Phylum Rotifera 306 Phylum Gastrotricha 309 Phylum Kinorhyncha 310 Phylum Loricifera 310 Phylum Priapulida 311 Phylum Nematoda: Roundworms 311 Phylum Nematomorpha 317
Phylum Acanthocephala 318 Phylum Entoprocta 319
Phylogeny and Adaptive Radiation
320 Summary 322
CHAPTER 16 Molluscs 325
The Molluscs 326 Form and Function 327 Classes of Molluscs 337 Phylogeny and Adaptive Radiation
350 Summary 353
CHAPTER 17
Body Plan 357 Class Polychaeta 358 Class Oligochaeta 364 Class Hirudinea: Leeches 369 Evolutionary Significance of
Metamerism 371 Phylogeny and Adaptive Radiation
371 Summary 373
CHAPTER 18
Phylum Arthropoda 376 Subphylum Trilobita 378 Subphylum Chelicerata 378 Phylogeny and Adaptive Radiation
384 Summary 387
CHAPTER 19 Aquatic Mandibulates 389
Subphylum Crustacea 390
A Brief Survey of Crustaceans 399 Phylogeny and Adaptive Radiation
406 Summary 409
CHAPTER 20 Terrestrial Mandibulates 411
Class Chilopoda 412 Class Diplopoda 412 Class Pauropoda 413 Class Symphyla 413 Class Insecta 414 Insects and Human Welfare 430
173 Summary 177
THE DIVERSITY OF ANIMAL
LIFE
CHAPTER 9 Architectural Pattern
of an Animal 180
The Hierarchical Organization of
Animal Complexity 181 Extracellular Components of the
Metazoan Body 183 Types of Tissues 183 Animal Body Plans 188 Summary 194
CHAPTER 10 Classification and Phylogeny
of Animals 196
Linnaeus and the Development of
Classification 197 Taxonomic Characters and
Phylogenetic Reconstruction 198
Theories of Taxonomy 200 Species 204
Trang 8Ancestry and Evolution 493 Subphylum Urochordata (Tunicata)
494 Subphylum Cephalochordata 497 Subphylum Vertebrata (Craniata) 498 Summary 505
CHAPTER 26 Fishes 507
Ancestry and Relationships of Major
Groups of Fishes 508 Superclass Agnatha: Jawless Fishes
511 Class Chondrichthyes: Cartilaginous
Fishes 514 Osteichthyes: Bony Fishes 518 Structural and Functional Adaptations
of Fishes 524 Summary 534
CHAPTER 27 Early Tetrapods and Modern
Movement onto Land 539 Early Evolution of Terrestrial
Vertebrates 539 Modern Amphibians 543 Summary 557
CHAPTER 28 Reptilian Groups 559
Origin and Adaptive Radiation of
Reptilian Groups 560 Characteristics of Reptiles that
Distinguish Them from Amphibians 563 Characteristics and Natural History of
Reptilian Orders 565 Summary 578
CHAPTER 29 Birds 581
Origin and Relationships 582 Form and Function 586 Migration and Navigation 597 Social Behavior and Reproduction 599 Bird Populations 602
ix
Phylogeny and Adaptive Radiation
434 Summary 437
CHAPTER 21
Lesser Protostomes 440 Phylum Sipuncula 440 Phylum Echiura 441 Phylum Pogonophora 442 Phylum Pentastomida 444 Phylum Onychophora 445 Phylum Tardigrada 446 Phylogeny 447
Summary 449
CHAPTER 22
Lophophorates 452 Phylum Phoronida 452 Phylum Ectoprocta (Bryozoa) 453 Phylum Brachiopoda 454
Phylogeny and Adaptive Radiation
456 Summary 456
CHAPTER 23
Echinoderms 459 Class Asteroidea 461 Class Ophiuroidea 466 Class Echinoidea 468 Class Holothuroidea 471 Class Crinoidea 473 Class Concentricycloidea 474 Phylogeny and Adaptive Radiation
474 Summary 478
CHAPTER 24 Chaetognaths and
Phylum Chaetognatha 481 Phylum Hemichordata 482 Phylogeny and Adaptive Radiation
485 Summary 486
CHAPTER 25 Chordates 488
The Chordates 489 Four Chordate Hallmarks 490
Trang 9CHAPTER 32
Water and Osmotic Regulation 665 Invertebrate Excretory Structures 668 Vertebrate Kidney 670
Temperature Regulation 676 Summary 681
Respiration 695 Summary 704
CHAPTER 34
Digestion and Nutrition 706
Feeding Mechanisms 707 Digestion 710
Organization and Regional Function of
the Alimentary Canal 712 Regulation of Food Intake 718 Nutritional Requirements 719 Summary 722
CHAPTER 35
Neurons: Functional Units of Nervous
Systems 725 Synapses: Junctions Between Nerves
728 Evolution of Nervous Systems 730 Sense Organs 736
CHAPTER 37
Susceptibility and Resistance 770 Innate Defense Mechanisms 770 Acquired Immune Response in
Vertebrates 771 Blood Group Antigens 778 Immunity in Invertebrates 779 Summary 781
CHAPTER 40
The Hierarchy of Ecology 823 Summary 838
Trang 10ABOUT THE AUTHORS
Allan Larson
Allan Larson is a professor at ton University, St Louis, MO Hereceived his Ph.D in Genetics at theUniversity of California, Berkeley Hisfields of specialization include evolu-tionary biology, molecular populationgenetics and systematics, and amphib-ian systematics He teaches courses inmacroevolution, molecular evolution,and the history of evolutionary theory,and has organized and taught a specialcourse in evolutionary biology for high-school teachers
Washing-Dr Larson has an active research oratory that uses DNA sequences toexamine evolutionary relationships among vertebrate species, especially insalamanders, lizards, fishes, and pri-mates The students in Dr Larson’s lab-oratory have participated in zoologicalfield studies around the world, includ-ing projects in Africa, Asia, Australia,Madagascar, North America, SouthAmerica, and the Caribbean Islands
lab-Dr Larson has authored numerous scientific publications, and has edited
for the journals Evolution, Molecular Phylogentics and Evolution, and Sys- tematic Biology Dr Larson serves as
an academic advisor to undergraduatestudents and supervises the undergrad-uate biology curriculum at WashingtonUniversity
Dr Larson can be contacted at:
Interna-author of Schmidt and Roberts’ dations of Parasitology, sixth edition.
Foun-Dr Roberts is also co-author of grated Principles of Zoology, Biology of Animals, and Animal Diversity.
Inte-Dr Roberts has published manyresearch articles and reviews He isactively involved in the American Soci-ety of Parasitologists, and is a member
of numerous professional societies Dr
Roberts also serves on the Editorial
Board of the journal, Parasitology Research His hobbies include scuba
diving, underwater photography, andtropical horticulture
Dr Roberts can be contacted at:
to Washington and Lee University in
1967 He has published numerousarticles and research papers in fishphysiology, in addition to co-authoring
the highly successful texts: Integrated Principles of Zoology, Biology of Ani- mals, Animal Diversity, and Laborato-
ry Studies in Integrated Principles of Zoology.
Over the years, Dr Hickman has ledmany field trips to the GalápagosIslands His current research is onintertidal zonation and marine inverte-brate systematics in the Galápagos
He has published two field guides
in the Galápagos Marine Life Series for the identification of echinodermsand marine molluscs His interestsinclude scuba diving, woodworking,and participating in chamber musicensembles
Dr Hickman can be contacted at:
hickman.c@wlu.edu
xi
Trang 11Integrated Principles of Zoology is a
college text adaptable to any ductory course in zoology Thiseleventh edition, as with previous edi-tions, describes the diversity of animallife and the fascinating adaptations thatenable animals to inhabit nearly allconceivable ecological niches Weretain in this revision the basic organi-zation of the tenth edition and its dis-tinctive features, especially emphasis
intro-on the principles of evolutiintro-on and logical science Also retained are sev-eral pedagogical features that havemade previous editions easily accessi-ble to students: opening chapter dia-logues drawn from the chapter’stheme; chapter summaries and reviewquestions to aid student comprehen-sion and study; accurate and visuallyappealing illustrations; in-text deriva-tions of generic names; chapter notesand essays that enhance the text byoffering interesting sidelights to thenarrative; and an extensive glossaryproviding pronunciation, derivation,and definition of terms used in the text
zoo-New to the Eleventh Edition
Many of the changes in this editionwere guided by the suggestions ofmore than 60 zoology instructors whoread and commented on sections ofthe tenth edition In addition, the ver-tebrate chapters of Part Three, andseveral chapters on functional systems(Part Four) were revised by invitedContributors, all experienced zoolo-gists who were solicited for their inter-est and expertise in the subject matter
of specific chapters In general, allchapters were revised to make thetext current while eliminating exces-sive detail, and to place more empha-sis on experimentation and compara-tive studies in zoology
Chapter Organization
• Separate treatments of the origin oflife and chemistry of life are con-densed into a single chapter (Chap-ter 2), thus streamlining the presen-
tation by discussing basic chemistry
in the context of the origin of life
• The order of chapters in Part Two
is altered to offer a better studysequence for students, providing agrounding in genetics and evolu-tionary theory before undertakingthe chapters on reproduction anddevelopment There are numerousplaces in the development chapter
in which an understanding ofgenetics is crucial
• A completely new chapter onimmunology (Chapter 37) wasdeveloped, covering both verte-brate and invertebrate immunologyand embracing many new discov-eries in this fast-moving field
New Pedagogy
• Throughout the text we updatedreferences, revised or replacedmany illustrations, and rewrotemany of the Review Questions toprovoke thought and reduceemphasis on rote memorization
PREFACE
PREAMBLE
How does one direct the revision of
a classic? As the Editor faced with theresponsibility of instructing authors toimprove further an incredibly suc-cessful and comprehensive text, Ithought the answer to be a specialfocus on “contemporary.” Theeleventh edition is a bridge to thetwenty-first century in teaching gen-eral zoology It combines classicalcoverage of animal biology with newresearch, new phylogenies, and newtechnologies
Students using this text will beexposed to the most current coverage
of zoology in addition to being thefirst to have integrated multimedia aspart of their studies Integrated Prin- ciples of Zoology is supported by a
tutorial CD-ROM, the Essential StudyPartner; an Online Learning CenterWeb site with additional readings,animations, and quizzing; and a Visual Resource Library CD-ROM that contains 1,000 line drawings and photos to enhance lecturepresentations
Along with the authors, our rial team strives to produce the finesteducational resources to support yourinstructional and educational objec-tives I invite you to read, enjoy, andrespond to a classic of the twenty-firstcentury!
edito-Margaret J Kemp
Sr Sponsoring Editor
marge_kemp@mcgraw-hill.com
Trang 12• Suggested Internet topics areadded at the end of each chapter; hyperlinks are available
on this text’s Online LearningCenter web site at
www.mhhe.com/zoology
• The end paper on Origin of Lifeand Geologic Time Table hasbeen replaced with a revised ver-sion in full color
The principal revisions areexplained below
Part One: Introduction to the Living Animal
• Chapters 2 (Chemistry) and 3 gin of Life) now form an inte-grated review of the kinds oforganic molecules found in livingsystems and their origins in theearth’s primitive reducing atmos-phere A review of basic chemistry(atoms, elements, and molecules;
(Ori-bonding theory; acids, bases, salts,and buffers) is available for refer-ence; it will be found at ourOnline Learning Center web site
www.mhhe.com/zoology)
• For Chapter 3, on cells as units oflife, we revised the discussion ofcell structure and cell junctions,and reorganized the sequence ofcertain topics Several illustrations
in this and the following chapter
on cellular metabolism wereredrawn for this edition
Part Two: Continuity and Evolution of Animal Life
• Chapter 5, Principles of Genetics,features a revised section on mol-ecular genetics, adding a newcoverage of genomics and a newsubsection on molecular systemat-ics The increasing ease withwhich genes can be sequencedand compared to sequences of thesame gene in other taxa has led to
a great many revisions of genies based on sequence analy-sis Such findings have made nec-essary many changes in the
phylo-diversity chapters in Part Three ofthis book
• Chapter 7, The ReproductiveProcess, was revised to clarify rela-tionships among bisexual repro-duction, hermaphroditism, andparthenogenesis A new section onsex determination summarizes themost recent understanding of themale determining gene and mas-culinizing hormones, and discov-ery of the sex reversing X region
on the X chromosome and its role
in promoting ovary formation Thefinal section on endocrine eventsthat orchestrate reproduction wasrewritten and updated
• Chapter 8, Principles of ment, was extensively revised inboth text and line art The order inwhich material on cleavage is pre-sented was reorganized to clarifyrelationships among principal top-ics of yolk amount and distribu-tion, cleavage type, cleavage pat-tern, and subtopics of direct andindirect development, mosaic ver-sus regulative development, anddifferences between protostomesand deuterostomes Cleavage ofcentrolecithal eggs was added Thesection on gastrulation now com-pares the process in sea stars, rep-tiles, birds, and mammals Amongother sections revised and updatedwere those on cytoplasmic specifi-cation and homeotic genes
Develop-Part Three: The Diversity
diver-of this chapter were revised: plexity and body size, musculartissue, animal body plans, bodycavities, and terminology used inspecifying aspects of symmetry
com-• Chapter 10, Classification and logeny of Animals, explains theprinciples of animal taxonomy and
Phy-how they are applied by the peting schools of evolutionary tax-onomy and cladistics Becauseclassification pervades everycourse in zoology, students shouldunderstand that systematics pro-vides the evolutionary basis forzoological study Changes includerevision of systematics of greatapes to use a cladistic classifica-tion, and updating of the material
com-on classificaticom-on of the Bilateria toincorporate results of new molecu-lar phylogenetic studies
• The title of Chapter 11 waschanged from “The Animal-likeProtista” to “Protozoan Groups.”Although both Protozoa and Pro-tista no longer are consideredvalid taxa, we continue to use theterms “protozoa” and “protozoan”informally to distinguish these animal-like phyla Among sectionsrevised in the protozoan chapterare pseudopodial movement,mechanism of contractile vacuoleaction, and the final sections onphylogeny and classification
• For Chapter 12 (Mesozoa andParazoa) we revised the sections
on origin and phylogeny of zoa, and deleted reference to classSclerospongiae, which is no longerrecognized as a valid taxon
Meta-• We made several changes inChapters 14 and 15 on acoelomateand pseudocoelomate animals,including reorganization of thematerial on class Turbellaria, andrevision of the phylogeny sectionsfor both chapters There is evi-dence now that acoels (orderAcoela) are not flatworms butform the sister group for all otherBilateria All remaining acoelo-mates are now placed in thenewly erected protostome super-phylum Lophotrochozoa
• Each of the pseudocoelomatephyla is assigned to eitherLophotrochozoa or to the alterna-tive superphylum Ecdysozoa Phy-logeny sections for mollusc,annelid, and arthropod chaptersalso were revised to embrace newxiv
Trang 13information from sequence sis, which places Mollusca andAnnelida in superphylumLophotrochozoa, and Arthropoda
analy-in superphylum Ecdysozoa Wepoint out, however, that analysisupon which the Lophotrochozoa/
Ecdysozoa hypothesis is basedfails to support monophyly ofMollusca and Annelida Neverthe-less, few if any zoologists believemolluscs and annelids are notmonophyletic groups
• In Chapter 20, on terrestrial dibulates, we introduce the termparasitoid and emphasize theimportance of parasitoids in con-trolling populations of other insects
man-Among other changes in this ter we strengthened coverage ofpheromones, including use ofpheromone baits in insect traps andimportance of such use in monitor-ing insects of economic importance
chap-• Lophophorate animals (Chapter22) are now assigned to Protosto-mia, forming an important group
in superphylum Lophotrochozoa Iflophophorates are protostomes asmost recent evidence suggests, thetrimerous coelomic arrangementmust have evolved independently
in protostomes and deuterostomes
• Chapter 25 (chordates) receivedminor revision, including rework-ing sections on ancestry and evo-lution, chordate fossil discoveries,and position of amphioxus inspeculations on chordate ancestry
• Chapter 26 on fishes was sively revised With Osteichthyes
exten-no longer considered a valid taxon,Actinopterygii and Sarcopterygii areelevated to class; this change isaccompanied by a discussion of theorigin and radiation of ray-finnedfishes, radiation of the neoptery-gians, and morphological trendsthat permitted great diversification
of the teleosts Introductory tions on ancestry, relationships, andbiology of fishes were rewritten toclarify relationships among majorfish groups Revisions in the section
sec-on sharks include discussisec-ons of
sensory systems, shark attacks, andreproduction Several changes weremade in the art program, includingcorrections in synapomorphies inthe cladogram of fishes
• The title of Chapter 28 waschanged to Reptilian Groups toemphasize paraphyly in class Reptilia Topics revised in thischapter include lung breathing inturtles, viviparity, and characteris-tics that distinguish reptiles fromamphibians
• In the bird chapter (Chapter 29) weadded a note on recent fossil birddiscoveries, and revised discus-sions of skeletal weight compar-isons in birds and mammals, birdkidney function, and sun-azimuthorientation of bird migration Wereorganized the treatment of forms
of bird wings for flight and added
a new illustration to show hoveringflight in hummingbirds
• Chapter 30, Mammals, includes anupdated discussion of the firsthominids to summarize recent fos-sil finds, and a revised illustration
of hominid skulls Other changes:
adoption of a cladistic tion for primates, and revision ofdiscussions of horns and antlers,glands, feeding specializations,body weight and food consump-tion, and reproductive patterns
classifica-Part Four: Activity of Life
• The revisions for Chapter 31, port, Protection, and Movement,include discussions of skin cancerfrom sunlight, mechanisms of cil-iary movement, energy for musclecontraction, fast and slow fibers,and description of dermal deriva-tive in vertebrates
Sup-• Chapter 32, Homeostasis, wasupdated throughout Treatmentsrevised include hyperosmotic reg-ulation in invertebrates, hypoos-motic regulation in fishes, sharkkidney function, mechanism ofcontractile vacuole function, andglomerular filtration
• A major improvement in flow andunity of Chapter 33, Internal Fluidsand Respiration, was transfer ofdefense mechanisms and immunity
to a separate chapter (Chapter 37)
• Chapter 34, Digestion and tion, includes a discussion on nutri-tional requirements to embracenew understanding of relationshipsamong the hunger center, brownfat, the protein thermogenin, andthe recently discovered hormoneleptin We also updated statistics onworld meat consumption, malnutri-tion, and world population Thediscussion on gastrointestinal hor-mones, previously included in theendocrine chapter, was moved tothis chapter
Nutri-• The chapter on nervous tion (Chapter 35) was revisedthroughout The most importantrevisions appear in sections deal-ing with nature of the nerveimpulse, synapses, evolution ofinvertebrate nervous systems,reflex acts and reflex arcs, auto-nomic nervous systems, odorreception, and color vision
coordina-• Chapter 36, Chemical tion, features an updated section
Coordina-on secCoordina-ond messenger system, andnew sections that describe therole of growth hormone as a dia-betogenic hormone, and action ofthe most recently discovered hor-mone, leptin, in regulating eatingbehavior and energy balance
• Chapter 37, Immunity, is new and
covers the topics of susceptibilityand resistance, innate defensemechanisms, acquired immuneresponse in vertebrates, bloodgroup antigens, and immunity ininvertebrates The section onacquired immune response in ver-tebrates includes descriptions ofself–nonself discrimination (MHCproteins), recognition molecules(antibodies and T-cell receptors),cytokines, humoral response (TH2arm), and cell-mediated response(TH1 arm)
• Chapter 38 concludes this unitwith a discussion of animal
xv
Trang 14behavior It features an expandedexplanation of the ritualization ofbehavior, and new sections ondiversity of mating systems, altru-istic behavior and kin selection,and animal cognition The latterdescribing the remarkable studies
of the Gardners with the panzee Washoe, and Pepperberg’swork with an African grey parrot
chim-Part Five: The Animal and Its Environment
• Chapter 39, The Biosphere andAnimal Distribution, includes anupdated discussion of the pro-posed effect of carbon dioxide onthe earth’s climate It also provides
an expanded explanation of theearth’s heat engine, with accom-panying new art, and added meanannual temperature and rainfallvalues to all biome descriptions
• Chapter 40, Animal Ecology, wascompletely rewritten to providemuch greater emphasis on popu-lational and community ecology
It features expanded explanations
of niche, characteristics of tion (age structure, growth rates,survivorship), population regula-tion, and interactions among pop-ulations in communities
popula-Teaching and Learning Aids
To help students in vocabulary
development, as in previous editions
we have boldfaced key words, andprovided the derivations of technicaland zoological terms, and genericnames of animals where they firstappear in the text In this way stu-dents gradually become familiar withthe more common roots that comprisemany technical terms An extensiveglossary of almost 1,100 terms pro-vides pronunciation, derivation, anddefinition of each term Many newterms were added to the glossary orrewritten for this edition
A distinctive feature of this text is
a chapter prologue for each chapter
that draws out some theme or factrelating to the subject of the chapter
Some present biological, particularlyevolutionary, principles; others (espe-cially those in the survey sections) illu-minate distinguishing characteristics ofthe group treated in the chapter Each
is intended to present an importantconcept drawn from the chapter in aninteresting manner that will facilitatelearning by students, as well as engagetheir interest and pique their curiosity
Chapter notes, which appear
throughout the book, augment thetext material and offer interesting side-lights without interrupting the narra-tive We prepared many new notes forthis edition and revised several of theexisting notes
To assist students in chapter
review, each chapter ends with a
con-cise summary, a list of review tions, and annotated selected refer- ences The review questions enable
ques-the student to self-test retention andunderstanding of the more importantchapter material
The historical appendix, unique
to this textbook, lists key discoveries inzoology, and separately describesbooks and publications that havegreatly influenced the development ofzoology Many readers have found thisappendix an invaluable reference to beconsulted long after their formal train-ing in zoology The historical appendixwill be found on this textbook’s OnlineLearning Center web site at
www.mhhe.com/zoology
Again, William C Ober and Claire
W Garrison have enhanced the art
program for this text with many new
full color paintings that replace olderart, or that illustrate new material
Bill’s artistic skills, knowledge of ogy, and experience gained from anearlier career as a practicing physician,have enriched this text through seven
biol-of its editions Claire practiced atric and obstetric nursing before turn-ing to scientific illustration as a full-time career Texts illustrated by Billand Claire have received nationalrecognition and won awards from the
pedi-Association of Medical Illustrators,American Institute of Graphic Arts,Chicago Book Clinic, Printing Indus-tries of America, and BookbuildersWest They are also recipients of theArt Directors Award
Supplements
The Instructor’s Manual and Test
Item File provides annotated chapter
outlines, chapter-specific changes forthis edition, lecture enrichment sugges-tions, commentaries and lesson plans,questions for advanced classes, and alisting of resource references for eachchapter Also included is a listing oftransparencies and slides availablewith the book, and a comprehensivetest bank offering 35 to 50 objectivequestions per chapter We trust thiswill be of particular value to first-timeusers of the text, although experiencedteachers may also find much of value
The Laboratory Manual by
Cleveland P Hickman, Jr., Frances M
Hickman, and Lee B Kats, Laboratory Studies in Integrated Zoology, has been
revised to include new exercises onmolecular techniques This manual can
be adapted conveniently for two mester, one semester, or term courses
se-by judicious selection of exercises.Test questions contained in theInstructor’s Manual and Test File are
also available as a Computerized
Test Bank, a test-generation system
for IBM and Macintosh computers.Using this system, instructors can cre-ate tests or quizzes quickly and easily.Questions can be sorted by type orlevel of difficulty, and instructors alsocan add their own material to thebank of questions provided
A set of 150 full-color parency acetates of important textual
trans-illustrations are available with this
edi-tion of Integrated Principles of Zoology Labeling is clear, dark, and
bold for easy reading
A set of 148 animal diversityslides, photographed by the authorsand Bill Ober on their various excur-sions, are offered in this unique text-book supplement Both invertebratesand vertebrates are represented.xvi
Trang 15Descriptions, including specific names
of each animal and brief overview ofthe animal’s ecology and/or behavior,accompany the slides
A Zoology Visual Resource
Library CD-ROM, containing 1,000
line drawings and photos, is nowavailable to instructors to enhance lec-ture presentations (see page xxiv formore details)
A tutorial CD-ROM, the Essential
Study Partner, will be available soon
to aid students in their study of zoology(see page xxi for more details)
An Online Learning Center web
site is available with this edition, and
contains additional readings, tions, quizzing, key terms flashcards,cladogram exercises, and much more(see page xix for specific information)
anima-Check it out at
www.mhhe.com/zoology
By the end of 2000, this text willalso be available in a CD-ROM format,complete with hyperlinks to theOnline Learning Center, an interactiveglossary, and animations (see pagexxii for more details)
Acknowledgments
We wish to thank the following gists who were engaged by McGraw-Hill to contribute directly to the revi-sion of specific chapters Thesepersons, and the chapters to whichthey contributed, are:
zoolo-Sylvester Allred, Northern Arizona UniversityChapter 30 MammalsAndrew Blaustein, Oregon State UniversityChapter 38 Animal BehaviorDavid Eisenhour,
Morehead State UniversityChapter 26 Fishes
Helen I’Anson, Washington and Lee UniversityChapter 7 The ReproductiveProcess
Chapter 35 Nervous CoordinationChapter 36 Chemical CoordinationLawrence E Hurd,
Washington and Lee University
Chapter 40 Animal EcologySharyn Marks, Humboldt StateUniversity
Chapter 8 Principles ofDevelopment
Ron Myers, Weber State UniversityChapter 28 Reptilian GroupsChapter 31 Support, Protection,and Movement
Bruce Wunder, Colorado StateUniversity
Chapter 29 BirdsThe authors extend their warmestthanks to reviewers who suggestednumerous improvements and whosecollective wisdom was of the greatestassistance to us as we approached thisedition Their experience with stu-dents of varying backgrounds, andtheir interest in and knowledge of thesubject, helped to shape the text intoits final form
Barbara J Abraham, HamptonUniversity
Felix Akojie, Paducah CommunityCollege
David Bass, University of CentralOklahoma
R P Benard, American InternationalCollege
Gerald Bergman, Northwest StateCollege
Patricia M Biesiot, University ofSouthern MississippiDel Blackburn, Clark CollegeMarilyn S Branton, Stillman CollegeKimberly “Rusty” Brown, MississippiGulf Coast Community College,Jackson County CampusBruce R Burnham, United States AirForce Academy
Paul J Bybee, Utah Valley StateCollege
Suzzette F Chopin, Texas A&MUniversity
Phillip D Clem, University ofCharleston
Mariette S Cole, Concordia UniversitySarah Cooper, Beaver College
Michael Craig, Central CollegeJohn R Crooks, Iowa WesleyanCollege
David Cunnington, North IdahoCollege
Charles Dailey, Sierra CollegeAaron R Davis, East CentralCommunity CollegeArmando A de la Cruz, MississippiState University
Lorri Dennis, Alfred State CollegeElizabeth A Desy, Southwest StateUniversity
Elizabeth Drumm, OaklandCommunity CollegePeter Ducey, State University of NewYork–Cortland
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xvii
Trang 16Sarah H Swain, Middle TennesseeState University
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Trang 17Student Resoures
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Trang 19Essential Study Partner CD-ROM
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Trang 22Visual Resource Library CD-ROMs
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Zoology Visual Resource
Trang 23P A R T O N E
Introduction to the Living Animal
1 Life: Biological Principles and the Science of Zoology 2 The Origin and Chemistry of Life
3 Cells as Units of Life 4 Cellular Metabolism
clamitans,in a Michigan pond.
Trang 24The Uses of Principles
We gain knowledge of the animal world not in a passive orhaphazard manner but by actively applying important guid-ing principles to our investigations Just as the exploration
of outer space is both guided and limited by available nologies, exploration of the animal world depends critically
tech-on our questitech-ons, methods, and principles The body ofknowledge that we call zoology makes sense only when theprinciples that we use to construct it are clear
The principles of modern zoology have a long historyand many sources Some principles derive from the laws ofphysics and chemistry, which all living systems obey Othersderive from the scientific method, which tells us that ourhypotheses regarding the animal world are useless unlessthey guide us to gather data that potentially can refute them
Many important principles derive from previous studies of
the living world, of which animals are one part Principles ofheredity, variation, and organic evolution guide the study
of life from the simplest unicellular forms to the most plex animals, fungi, and plants Because all of life shares acommon evolutionary origin, principles learned from thestudy of one group often may be applied to other groups aswell By tracing the origins of our operating principles, wesee that zoologists are not an island unto themselves butform an integrated part of the scientific community
com-We begin our study of zoology not by focusing
narrow-ly within the animal world, but by searching broadnarrow-ly for ourmost basic principles and their diverse sources These prin-ciples simultaneously guide our studies of animals and inte-grate those studies into the broader context of humanknowledge ■
Zoologist studying the behavior of yellow baboons (Papio cynocephalus) in the
Amboseli Reserve, Kenya.
C H A P T E R
1
Life: Biological Principles and the Science of Zoology
2
Trang 25CHAPTER 1 Life: Biological Principles and the Science of Zoology 3
Zoology, the scientific study of animallife, builds on centuries of humaninquiry into the animal world Themythologies of nearly every humanculture document attempts to solve themysteries of animal life and its origin
Zoologists now confront these samemysteries with the most advancedmethods and technologies developedthroughout all branches of science Westart by documenting the diversity ofanimal life and organizing it in a sys-tematic way This complex and excitingprocess builds on the contributions ofthousands of zoologists working in all di-mensions of the biosphere (Figure 1-1)
We strive through this work to stand how animal diversity originatedand how animals perform the basicprocesses of life that permit them tothrive in many diverse environments
under-This chapter introduces the mental properties of animal life, themethodological principles on whichtheir study is based, and two importanttheories that guide our research: (1)the theory of evolution, which is thecentral organizing principle of biology,and (2) the chromosomal theory ofinheritance, which guides our study ofheredity and variation in animals
funda-These theories unify our knowledge ofthe animal world
Fundamental Properties of Life
Does Life Have Defining Properties?
We begin with the difficult question,What is life? Although many attemptshave been made to define life, simpledefinitions are doomed to failure
When we try to give life a simple nition, we look for fixed propertiesmaintained throughout life’s history
defi-However, the properties that lifeexhibits today (pp 3–10) are very dif-ferent from those present at its origin
The history of life shows perpetual
change, which we call evolution As
the genealogy of life progressed andbranched from the earliest living form
to the millions of species living today,
new properties evolved and passedfrom parents to their offspring
Through this process, living systemshave generated many rare and spectac-ular features that have no counterparts
in the nonliving world Unexpectedproperties emerge on many differentlineages in life’s evolutionary history,producing the great organismal diver-sity observed today
We might try to define life on thebasis of universal properties evident atits origin Replication of molecules, forexample, can be traced to life’s originand represents one of life’s universalproperties Defining life based onproperties present at its origin facesthe major problem that these are theproperties most likely to be shared bysome nonliving forms To study theorigin of life, we must ask how organicmolecules acquired the ability for pre-cise replication But where do we drawthe line between those replicativeprocesses that characterize life andthose that are merely general chemicalfeatures of the matter from which lifearose? Replication of complex crys-talline structures in nonliving chemicalassemblages might be confused, forexample, with the replicative molecu-lar properties associated with life If wedefine life using only the mostadvanced properties that characterizethe highly evolved living systemsobserved today, the nonliving worldwould not intrude on our definition,but we would eliminate the earlyforms of life from which all othersdescended and which give life its his-torical unity
Ultimately our definition of lifemust be based on the common history
of life on earth Life’s history of descentwith modification gives it an identityand continuity that separates it fromthe nonliving world We can trace thiscommon history backward throughtime from the diverse forms observedtoday and in the fossil record to theircommon ancestor that arose in theatmosphere of the primitive earth (seeChapter 2) All organisms forming part
of this long history of hereditarydescent from life’s common ancestorare included in our concept of life
We do not force life into a simpledefinition, but we can readily identifythe living world through its history ofcommon evolutionary descent and sep-arate it from the nonliving Manyremarkable properties have arisen dur-ing life’s history and are observed in var-ious combinations among living forms.These properties, discussed in the nextsection, clearly identify their possessors
as part of the unified historical entitycalled life All such features occur in themost highly evolved forms of life, such
as those that compose the animal dom Because they are so important formaintenance and functioning of livingforms that possess them, these proper-ties should persist through life’s futureevolutionary history
king-General Properties of Living Systems
The most outstanding general featuresthat have arisen during life’s historyinclude chemical uniqueness; com-plexity and hierarchical organization;reproduction (heredity and variation);possession of a genetic program; me-tabolism; development; and environ-mental interaction
1 Chemical uniqueness Living
sys-tems demonstrate a unique and complex molecular organization.
The history of life has featured theassembly of large molecules,known as macromolecules, that arefar more complex than the smallmolecules that constitute nonlivingmatter These macromolecules arecomposed of the same kinds ofatoms and chemical bonds thatoccur in nonliving matter and theyobey all fundamental laws ofchemistry; it is only the complexorganizational structure of thesemacromolecules that makes themunique We recognize four majorcategories of biological macromole-cules: nucleic acids, proteins, car-bohydrates, and lipids (see Chapter2) These categories differ in thestructures of their component parts,the kinds of chemical bonds thatlink their subunits together, andtheir functions in living systems
Trang 264 PART 1 Introduction to the Living Animal
The general structures of thesemacromolecules evolved and sta-bilized early in the history of life
With some modifications, thesesame general structures are found
in every form of life that weobserve today Proteins, for exam-ple, contain about 20 specifickinds of amino acid subunitslinked together by peptide bonds
in a linear sequence (Figure 1-2)
Additional bonds occurringbetween amino acids that are notadjacent to each other in the pro-tein chain give the protein a com-plex, three-dimensional structure(see Figures 1-2 and 2-11) A typi-cal protein contains several hun-
dred amino acid subunits Despitethe stability of this basic proteinstructure, the ordering of the dif-ferent amino acids in the proteinmolecule is subject to enormousvariation This variation underliesmuch of the diversity that weobserve among different kinds ofliving forms The nucleic acids,carbohydrates, and lipids likewisecontain characteristic bonds thatlink variable subunits (Chapter 2)
This organization gives living tems both a biochemical unity and
sys-a gresys-at potentisys-al for diversity
2 Complexity and hierarchical
organization Living systems
demonstrate a unique and
com-plex hierarchical organization.
Nonliving matter is organized atleast into atoms and moleculesand often has a higher degree oforganization as well However,atoms and molecules are com-bined into patterns in the livingworld that do not exist in the non-living world In living systems, wefind a hierarchy of levels thatincludes, in ascending order ofcomplexity, macromolecules,cells, organisms, populations, andspecies (Figure 1-3) Each levelbuilds on the level below it andhas its own internal structure,which is also often hierarchical.Within the cell, for example,
Figure 1-1
A few of the many dimensions of zoological research: A, Observing moray eels in Maui, Hawaii; B, Working with tranquilized polar bears; C, Banding
mallard ducks; D, observing Daphnia pulex (150) microscopically.
Trang 27CHAPTER 1 Life: Biological Principles and the Science of Zoology 5
macromolecules are compoundedinto structures such as ribosomes,chromosomes, and membranes,and these are likewise combined
in various ways to form evenmore complex subcellular struc-tures called organelles, such asmitochondria (see Chapters 3 and4) The organismal level also has ahierarchical substructure; cells arecombined into tissues, which arecombined into organs, which like-wise are combined into organ sys-tems (see Chapter 9)
Cells (Figure 1-4) are thesmallest units of the biologicalhierarchy that are semiautonomous
in their ability to conduct basicfunctions, including reproduction
Replication of molecules and cellular components occurs onlywithin a cellular context, not inde-pendently Cells are thereforeviewed as the basic units of livingsystems (Chapter 3) We can iso-late cells from an organism andcause them to grow and multiplyunder laboratory conditions in thepresence of nutrients alone Thissemiautonomous replication is notpossible for any individual mole-cules or subcellular components,
sub-Figure 1-2
A computer simulation of the three-dimensional structure of the lysozyme protein (A), which is used by animals to destroy bacteria The protein is a linear string of molecular subunits called amino acids, connected as shown in B, that fold in a three-dimensional pattern to form the active protein The white balls
correspond to carbon atoms, the red balls to oxygen, the blue balls to nitrogen, the yellow balls to sulfur, the green balls to hydrogen, and the black balls
(B) to molecular groups formed by various combinations of carbon, oxygen, nitrogen, hydrogen, and sulfur atoms that differ among amino acids Hydrogen atoms are not shown in A The purple molecule in A is a structure from the bacterial cell wall that is broken by lysozyme.
Figure 1-3
Volvox globator (see pp 224–225) is a
multicellular phytoflagellate that illustrates three different levels of the biological hierarchy:
cellular, organismal, and populational Each individual spheroid (organism) contains cells embedded in a gelatinous matrix The larger cells function in reproduction, and the smaller ones perform the general metabolic functions of the organism The individual spheroids together form a population.
Figure 1-4
Electron micrograph of ciliated epithelial cells and mucus-secreting cells (see pp 185–188) Cells are the basic building blocks of living organisms.
Trang 286 PART 1 Introduction to the Living Animal
which require additional cellularconstituents for their reproduction
Each successively higher level ofthe biological hierarchy is com-posed of units of the precedinglower level in the hierarchy Animportant characteristic of thishierarchy is that the properties ofany given level cannot beobtained from even the most com-plete knowledge of the properties
of its component parts A logical feature, such as blood pres-sure, is a property of the organis-mal level; it is impossible topredict someone’s blood pressuresimply by knowing the physicalcharacteristics of individual cells ofthe body Likewise, systems ofsocial interaction, as observed inbees, occur at the populationallevel; it would not be possible toinfer properties of this social sys-tem by knowing only properties ofindividual bees
physio-The appearance of new acteristics at a given level of orga-nization is called emergence , and
char-these characteristics are known as
emergent properties These
properties arise from interactionsthat occur among the componentparts of a system For this reason,
we must study all levels directly,and subdivisions of the field ofbiology (molecular biology; cellbiology; organismal anatomy,physiology and genetics; popula-tion biology) reflect this fact(Table 1-1) We find that emergentproperties expressed at a particu-lar level of the biological hierar-chy are certainly influenced andrestricted by properties of thelower-level components Forexample, it would be impossiblefor a population of organisms thatlack hearing to develop a spokenlanguage Nonetheless, properties
of parts of a living system do notrigidly determine the properties ofthe whole Many different spokenlanguages have emerged inhuman culture from the samebasic anatomical structures thatpermit hearing and speech The
freedom of the parts to interact indifferent ways makes possible agreat diversity of potential emer-gent properties at each level ofthe biological hierarchy
Different levels of the cal hierarchy and their particularemergent properties are products
biologi-of evolution Before multicellularorganisms evolved, there was nodistinction between the organis-mal and cellular levels, and it isstill absent from single-celledorganisms (Chapter 11) Thediversity of emergent propertiesthat we see at all levels of the bio-logical hierarchy contributes tothe difficulty of giving life a sim-ple definition or description
3 Reproduction Living systems
can reproduce themselves Life
does not arise spontaneously butcomes only from prior life,through a process of reproduc-tion Although life certainly origi-nated from nonliving matter atleast once (Chapter 2), this
Different Hierarchical Levels of Biological Complexity that Display Reproduction, Variation, and Heredity
Cell Hours (mammalian cell Cell biology Microscopy (light, Chromosomal replication
16 hours) electron), biochemistry (meiosis, mitosis),
synthesis of macromolecules (DNA, RNA, proteins, lipids, polysaccharides) Organism Hours to days Organismal anatomy, Dissection, genetic Structure, functions and
(unicellular); days physiology, genetics crosses, clinical studies coordination of tissues,
(blood pressure, body temperature, sensory perception, feeding) Population Up to thousands Population biology, Statistical analysis of Social structures, systems
of years population genetics, variation, abundance, of mating, age
ecology geographical distribution of organisms,
distribution levels of variation, action
of natural selection Species Thousands to Systematics and Study of reproductive Method of reproduction,
millions of years evolutionary biology, barriers, phylogeny, reproductive barriers
community ecology paleontology,
ecological interactions
TABLE 1.1
Trang 29CHAPTER 1 Life: Biological Principles and the Science of Zoology 7
required enormously long periods
of time and conditions very ent from those of the modernbiosphere At each level of thebiological hierarchy, living formsreproduce to generate others likethemselves (Figure 1-5) Genesare replicated to produce newgenes Cells divide to producenew cells Organisms reproduce,
differ-sexually or asexually , to
pro-duce new organisms (Chapter 5)
Populations can become mented to give rise to new popu-lations, and species can give rise
frag-to new species through a process
Figure 1-5
Reproductive processes observed at four different levels of biological complexity: A, Molecular level—electron micrograph of a replicating DNA molecule;
B, Cellular level—micrograph of cell division at mitotic telophase; C, Organismal level—a king snake hatching; D, Species level—formation of new species in the
sea urchin (Eucidaris) after geographic separation of Caribbean (E tribuloides) and Pacific (E thouarsi) populations by the formation of a land bridge.
known as speciation tion at any level of the hierarchyusually features an increase innumbers Individual genes, cells,organisms, populations, or speciesmay fail to reproduce themselves,but reproduction is nonetheless
Reproduc-an expected property of theseindividuals
Reproduction at each of theselevels features the complementary,and yet apparently contradictory,phenomena of heredity and vari- ation Heredity is the faithful
transmission of traits from parents
to offspring, usually (but not
organis-tion of differences among the
traits of different individuals Inthe reproductive process, theproperties of descendants resem-ble those of their parents to vary-ing degrees but are usually notidentical to them Replication ofdeoxyribonucleic acid (DNA)occurs with high fidelity, buterrors occur at repeatable rates.Cell division is an exceptionallyprecise process, especially withregard to the nuclear material, butchromosomal changes occur
Pacific Ocean
Central America
Caribbean Sea
Gulf of Mexico
D
Trang 308 PART 1 Introduction to the Living Animal
nonetheless at measurable rates
Organismal reproduction likewisedemonstrates both heredity andvariation, the latter being obviousespecially in sexually reproducingforms The production of newpopulations and species alsodemonstrates conservation ofsome properties and changes ofothers Two closely related frogspecies may have similar matingcalls but differ in the rhythm ofrepeated sounds
We will see later in this bookthat the interaction of heredityand variation in the reproductiveprocess is the basis for organicevolution (Chapter 6) If hereditywere perfect, living systemswould never change; if variationwere uncontrolled by heredity,biological systems would lack thestability that allows them to persistthrough time
4 Possession of a genetic
gram A genetic program
pro-vides fidelity of inheritance
(Fig-ure 1-6) The struct(Fig-ures of theprotein molecules needed fororganismal development andfunctioning are encoded in nu- cleic acids (Chapter 5) For ani-
mals and most other organisms,the genetic information is con-tained in DNA DNA is a very
long, linear chain of subunitscalled nucleotides, each of whichcontains a sugar phosphate(deoxyribose phosphate) and one
of four nitrogenous bases nine, cytosine, guanine, orthymine, abbreviated A, C, G, and
(ade-T, respectively) The sequence ofnucleotide bases represents acode for the order of amino acids
in the protein specified by theDNA molecule The correspon-dence between the sequence of
bases in DNA and the sequence ofamino acids in a protein is known
as the genetic code.
The genetic code was lished early in the evolutionary his-tory of life, and the same code ispresent in bacteria and in thenuclear genomes of almost all ani-mals and plants The near constan-
estab-cy of this code among living formsprovides strong evidence for a sin-gle origin of life The genetic codehas undergone very little evolution-ary change since its origin because
an alteration would disrupt thestructure of nearly every protein,which would in turn severely dis-rupt cellular functions that requirevery specific protein structures.Only in the rare instance in whichthe altered protein structures arestill compatible with their cellularfunctions would such a changehave a chance to survive and bereproduced Evolutionary change
in the genetic code has occurred inthe DNA contained in animal mito-chondria, the organelles that regu-late cellular energy The geneticcode in animal mitochondrial DNAtherefore is slightly different fromthe standard code of nuclear andbacterial DNA Because mitochon-drial DNA specifies far fewer pro-teins than nuclear DNA, the likeli-hood of getting a change in thecode that does not disrupt cellularfunctions is greater there than inthe nucleus
5 Metabolism Living organisms
maintain themselves by obtaining nutrients from their environments
(Figure 1-7) The nutrients arebroken down to obtain chemicalenergy and molecular componentsfor use in building and maintain-ing the living system (Chapter 4)
We call these essential chemicalprocesses metabolism They
include digestion, production ofenergy (respiration), and synthesis
of molecules and structures.Metabolism is often viewed as aninteraction of destructive (catabol-ic) and constructive (anabolic)reactions The most fundamental
A
B
Figure 1-6
James Watson and Francis Crick with a model
of the DNA double helix (A) Genetic information
is coded in the nucleotide base sequence inside the DNA molecule Genetic variation is shown
(B) in DNA molecules that are similar in base
sequence but differ from each other at four positions Such differences can encode alternative traits, such as different eye colors.
Trang 31CHAPTER 1 Life: Biological Principles and the Science of Zoology 9
anabolic and catabolic chemicalprocesses used by living systemsarose early in the evolutionaryhistory of life and are shared byall living forms These includesynthesis of carbohydrates, lipids,nucleic acids, and proteins andtheir constituent parts and thecleavage of chemical bonds torecover energy stored in them Inanimals, many fundamental meta-bolic reactions occur at the cellu-lar level, often in specific
organelles that are found out the animal kingdom Cellularrespiration occurs, for example, inthe mitochondria The cellular andnuclear membranes regulatemetabolism by controlling themovement of molecules across thecellular and nuclear boundaries,respectively The study of the per-formance of complex metabolicfunctions is known as physiolo-
through-gy We will devote a large portion
of this book to describing andcomparing the diverse tissues,organs, and organ systems thatdifferent groups of animals haveevolved to perform the basicphysiological functions of life(Chapters 11 through 37)
6 Development All organisms pass
through a characteristic life cycle.
Development describes the
char-acteristic changes that an organismundergoes from its origin (usuallythe fertilization of the egg bysperm) to its final adult form(Chapter 8) Development usuallyfeatures changes in size andshape, and the differentiation ofstructures within the organism
Even the simplest one-celledorganisms grow in size and repli-cate their component parts untilthey divide into two or more cells.Multicellular organisms undergomore dramatic changes duringtheir lives In some multicellularforms, different stages of their life
Trang 3210 PART 1 Introduction to the Living Animal
cycle are so dissimilar that they arehardly recognizable as part of thesame species Embryos are dis-tinctly different from juvenile andadult forms into which they willdevelop Even the postembryonicdevelopment of some organismsincludes stages that are dramati-cally different from each other
The transformation that occursfrom one stage to another is called
metamorphosis There is little
resemblance, for example, amongthe egg, larval, pupal, and adultstages of metamorphic insects(Figure 1-8) Among animals, theearly stages of development areoften more similar among organ-isms of related species than arelater developmental stages In oursurvey of animal diversity, we willdescribe all stages of observed lifehistories, but we will concentrate
on adult stages in which diversityboth within and between differentanimal groups tends to be greatest
7 Environmental interaction All
animals interact with their ronments The study of organismal
envi-interaction with the environment isknown as ecology Of special
interest are the factors that affectthe geographic distribution andabundance of animals (Chapters
39 and 40) The science of ecologypermits us to understand how anorganism can perceive environ-mental stimuli and respond inappropriate ways by adjusting its
metabolism and physiology ure 1-9) All organisms respond tostimuli in their environment, andthis property is called irritability
(Fig-The stimulus and response may besimple, such as a unicellularorganism moving from or toward alight source or away from a nox-ious substance, or it may be quitecomplex, such as a bird respond-ing to a complicated series of sig-nals in a mating ritual (see Chapter38) Life and the environment areinseparable We cannot isolate theevolutionary history of a lineage oforganisms from the environments
in which it occurred
Life Obeys Physical Laws
To untrained observers, these sevenproperties of life may appear to violatethe basic laws of physics Vitalism, theidea that life is endowed with a mysti-cal vital force that violates physical andchemical laws, was once widely advo-cated Biological research has consis-tently rejected vitalism, showinginstead that all living systems operateand evolve within the constraints ofthe basic laws of physics and chem-istry The laws governing energy andits transformations (thermodynamics)are particularly important for under-
standing life (Chapter 4) The first law
of thermodynamics is the law of
conservation of energy Energy is ther created nor destroyed, but it can
nei-be transformed from one form to
another All aspects of life requireenergy and its transformation Theenergy to support life on earth flowsfrom the fusion reactions in our sunand reaches the earth in the form oflight and heat Sunlight is captured bygreen plants and cyanobacteria andtransformed by photosynthesis intochemical bonds The energy in chemi-cal bonds is a form of potential energythat can be released when the bond isbroken; the energy is used to performnumerous cellular tasks Energy trans-formed and stored in plants is thenused by the animals that eat the plants,and these animals may in turn provideenergy for other animals that eat them
The second law of
thermody-namics states that physical systems
tend to proceed toward a state ofgreater disorder, or entropy The
energy obtained and stored by plants
is subsequently released by a variety ofmechanisms and finally dissipated asheat The high degree of molecularorganization found in living cells isattained and maintained only as long
as energy fuels the organization Theultimate fate of materials in the cells isdegradation and dissipation of theirchemical bond energy as heat Theprocess of evolution whereby organis-mal complexity can increase over timemay appear at first to violate the sec-ond law of thermodynamics, but itdoes not Organismal complexity isachieved and maintained only by theconstant use and dissipation of energyflowing into the biosphere from the
Late afternoon
Figure 1-9
A lizard regulates its body temperature by choosing different locations (microhabitats) at different times of day.
Trang 33CHAPTER 1 Life: Biological Principles and the Science of Zoology 11
sun The survival, growth, and duction of animals requires energy thatcomes from breaking complex foodmolecules into simple organic wasteproducts The processes by which ani-mals acquire energy through nutritionand respiration command the attention
repro-of the many physiological sciences
Zoology as a Part
of Biology
Animals form a distinct branch on theevolutionary tree of life It is a largeand old branch that originated in thePrecambrian seas over 600 millionyears ago Animals form part of aneven larger limb known as eukary- otes , organisms whose cells contain
membrane-enclosed nuclei This largerlimb includes the plants and fungi Per-haps the most distinctive characteristic
of the animals as a group is theirmeans of nutrition, which consists ofeating other organisms This basic way
of life has led to the evolution of manydiverse systems for locomotion and forcapturing and processing a wide array
of food items
Animals can be distinguished also
by the absence of properties that haveevolved in other eukaryotes Plants, forexample, have evolved the ability touse light energy to produce organiccompounds (photosynthesis), and theyhave evolved rigid cell walls that sur-round their cell membranes; photosyn-thesis and cell walls are absent fromanimals Fungi have evolved the ability
to acquire nutrition by absorption ofsmall organic molecules from theirenvironment, and they have a bodyplan consisting of tubular filaments
called hyphae; structures of this kind
are absent from the animal kingdom
Some organisms combine the erties of animals and plants For exam-
prop-ple, Euglena (Figure 1-10) is a motile,
single-celled organism that resemblesplants in being photosynthetic, but itresembles animals in its ability to eat
food particles Euglena is part of a
sep-arate eukaryotic lineage that divergedfrom those of plants and animals early
in the evolutionary history of
eukary-otes Euglena and other unicellular
eukaryotes are sometimes grouped intothe kingdom Protista, although thiskingdom is an arbitrary grouping ofunrelated lineages that violates taxo-nomic principles (see Chapter 10)
The fundamental structural anddevelopmental features evolved by theanimal kingdom are presented in detail
it is not, and how knowledge is gained
by using the scientific method
Science is a way of asking tions about the natural world and
ques-obtaining precise answers to them.Although science, in the modernsense, has arisen recently in humanhistory (within the last 200 years orso), the tradition of asking questionsabout the natural world is an ancientone In this section we examine themethodology that zoology shares withscience as a whole These features dis-tinguish the sciences from those activi-ties that we exclude from the realm ofscience, such as art and religion.Despite the enormous impact thatscience has had on our lives, manypeople have only a minimal under-standing of the real nature of science.For example, on March 19, 1981, thegovernor of Arkansas signed into lawthe Balanced Treatment for Creation-Science and Evolution-Science Act (Act
590 of 1981) This act falsely presented
“creation-science” as a valid scientificendeavor “Creation-science” is actually
a religious position advocated by aminority of the American religiouscommunity, and it does not qualify asscience The enactment of this law led
to a historic lawsuit tried in December
1981 in the court of Judge William R.Overton, U.S District Court, EasternDistrict of Arkansas The suit wasbrought by the American Civil LibertiesUnion on behalf of 23 plaintiffs,including a number of religious leadersand groups representing severaldenominations, individual parents, andeducational associations The plaintiffscontended that the law was a violation
of the First Amendment to the U.S.Constitution, which prohibits “estab-lishment of religion” by the govern-ment This prohibition includes pass-ing a law that would aid one religion
or prefer one religion over another OnJanuary 5, 1982, Judge Overton perma-nently enjoined the State of Arkansasfrom enforcing Act 590
Considerable testimony during thetrial dealt with the nature of science.Some witnesses defined science sim-ply, if not very informatively, as “what
is accepted by the scientific nity” and “what scientists do.” How-ever, on the basis of other testimony
commu-by scientists, Judge Overton was able
to state explicitly these essential acteristics of science:
Trang 3412 PART 1 Introduction to the Living Animal
1 It is guided by natural law
2 It has to be explanatory by ence to natural law
refer-3 It is testable against the able world
observ-4 Its conclusions are tentative, that
is, are not necessarily the finalword
5 It is falsifiable
The pursuit of scientific knowledgemust be guided by the physical andchemical laws that govern the state ofexistence Scientific knowledge mustexplain what is observed by reference
to natural law without requiring theintervention of a supernatural being orforce We must be able to observeevents in the real world, directly orindirectly, to test hypotheses aboutnature If we draw a conclusion rela-tive to some event, we must be readyalways to discard or to modify our con-clusion if further observations contra-dict it As Judge Overton stated, “Whileanybody is free to approach a scien-tific inquiry in any fashion theychoose, they cannot properly describethe methodology used as scientific ifthey start with a conclusion and refuse
to change it regardless of the evidencedeveloped during the course of theinvestigation.” Science is neutral on thequestion of religion, and the results ofscience do not favor one religiousposition over another
Scientific Method
These essential criteria of science formthe basis for an approach known as the
hypothetico-deductive method The
first step of this method is the generation
of hypotheses or potential answers tothe question being asked Thesehypotheses are usually based on priorobservations of nature, or they arederived from theories based on suchobservations Scientific hypotheses oftenconstitute general statements aboutnature that may explain a large number
of diverse observations Darwin’shypothesis of natural selection, forexample, explains the observations thatmany different species have propertiesthat adapt them to their environments
On the basis of the hypothesis, the
scien-tist must make a prediction about futureobservations The scientist must say, “If
my hypothesis is a valid explanation ofpast observations, then future observa-tions ought to have certain characteris-tics.” The best hypotheses are those thatmake many predictions which, if founderroneous, will lead to rejection, or falsi-fication, of the hypothesis
The hypothesis of natural selectionwas invoked to explain variationobserved in British moth populations(Figure 1-11) In industrial areas ofEngland having heavy air pollution,many populations of moths containprimarily darkly pigmented (melanic)individuals, whereas moth populationsinhabiting clean forests show a muchhigher frequency of lightly pigmentedindividuals The hypothesis suggeststhat moths can survive most effectively
by matching their surroundings, thereby remaining invisible to birdsthat seek to eat them Experimentalstudies have shown that, consistent
with this hypothesis, birds are able tolocate and then to eat moths that donot match their surroundings, but thatbirds in the same area frequently fail tofind moths that match their surround-ings Another testable prediction of thehypothesis of natural selection is thatwhen polluted areas are cleaned, themoth populations should demonstrate
an increase in the frequency of lightlypigmented individuals Observations ofsuch populations confirmed the resultpredicted by natural selection
If a hypothesis is very powerful inexplaining a wide variety of relatedphenomena, it attains the status of atheory Natural selection is a goodexample Our example of the use ofnatural selection to explain observedpigmentation patterns in moth popula-tions is only one of many phenomena
to which natural selection applies ural selection provides a potentialexplanation for the occurrence ofmany different traits distributed among
Nat-Figure 1-11
Light and melanic forms of the peppered moth,
Biston betularia on, A, a lichen-covered tree in
unpolluted countryside and, B, a soot-covered
tree near industrial Birmingham, England These color variants have a simple genetic basis
C, Recent decline in the frequency of the
melanic form of the peppered moth with falling air pollution in industrial areas of England The frequency of the melanic form still exceeded 90% in 1960, when smoke and sulfur dioxide emissions were still high Later, as emissions fell and light-colored lichens began to grow again
on the tree trunks, the melanic form became more conspicuous to predators By 1986, only 50% of the moths were still of the melanic form, the rest having been replaced by the light form.
Number
of melanic moths
C
B
Trang 35CHAPTER 1 Life: Biological Principles and the Science of Zoology 13
virtually all animal species Each ofthese instances constitutes a specifichypothesis generated from the theory
of natural selection Note, however,that falsification of a specific hypothe-sis does not necessarily lead to rejec-tion of the theory as a whole Naturalselection may fail to explain the origins
of human behavior, for example, but itprovides an excellent explanation formany structural modifications of thepentadactyl (five-fingered) vertebratelimb for diverse functions Scientiststest many subsidiary hypotheses oftheir major theories to ask whethertheir theories are generally applicable
The most useful theories are those thatcan explain the largest array of differ-ent natural phenomena
We emphasize that the meaning ofthe word “theory,” when used by sci-entists, is not “speculation” as it is inordinary English usage Failure tomake this distinction has been promi-nent in creationist challenges to evolu-tion The creationists have spoken ofevolution as “only a theory,” as if itwere little better than a guess In fact,the theory of evolution is supported bysuch massive evidence that most biolo-gists view repudiation of evolution astantamount to repudiation of reason
Nonetheless, evolution, along with allother theories in science, is not proven
in a mathematical sense, but it istestable, tentative, and falsifiable Pow-erful theories that guide extensive
research are called paradigms The
history of science has shown that evenmajor paradigms are subject to refuta-tion and replacement when they fail toaccount for our observations of thenatural world They are then replaced
by new paradigms in a process known
as a scientific revolution For
exam-ple, prior to the 1800s, animal specieswere studied as if they were speciallycreated entities whose essential prop-erties remained unchanged throughtime Darwin’s theories led to a scien-tific revolution that replaced theseviews with the evolutionary paradigm
The evolutionary paradigm has guidedbiological research for more than 130years, and to date there is no scientific
evidence that falsifies it; it continues toguide active inquiry into the naturalworld, and it is generally accepted asthe cornerstone of biology
Experimental versus Evolutionary Sciences
The many questions that people haveasked about the animal world since thetime of Aristotle can be grouped intotwo major categories.* The first cate-gory seeks to understand the proxi-
underlie the functioning of biologicalsystems at a particular time and place
These include the problems of ing how animals perform their meta-bolic, physiological, and behavioralfunctions at the molecular, cellular,organismal, and even populational lev-els For example, how is genetic infor-mation expressed to guide the synthe-sis of proteins? What causes cells todivide to produce new cells? How doespopulation density affect the physiol-ogy and behavior of organisms?
explain-The biological sciences that dress proximate causes are known as
ad-experimental sciences, and they
proceed using the experimentalmethod This method consists of threesteps: (1) predicting how a systembeing studied will respond to a distur-bance, (2) making the disturbance, andthen (3) comparing the observedresults with the predicted ones Experi-mental conditions are repeated toeliminate chance occurrences thatmight produce erroneous conclusions
Controls—repetitions of the mental procedure that lack the distur-bance—are established to protectagainst any unperceived factors thatmay bias the outcome of the experi-ment The processes by which animalsmaintain a body temperature underdifferent environmental conditions,digest their food, migrate to new habi-tats, or store energy are some addi-tional examples of physiological phe-nomena that are studied by experiment(Chapters 31 through 38) Subfields ofbiology that constitute experimentalsciences include molecular biology,cell biology, endocrinology, develop-mental biology, and community ecology
experi-In contrast to questions concerningthe proximate causes of biological sys-tems are questions of the ultimate causes that have produced these sys-
tems and their distinctive characteristicsthrough evolutionary time For exam-ple, what are the evolutionary factorsthat caused some birds to acquire com-plex patterns of seasonal migrationbetween temperate and tropical areas?Why do different species of animalshave different numbers of chromo-somes in their cells? Why do some ani-mal species maintain complex socialsystems, whereas the animals of otherspecies are largely solitary?
The biological sciences that dress questions of ultimate cause are
ad-known as evolutionary sciences, and they proceed largely using the com-
parative method rather than
experi-mentation Characteristics of molecularbiology, cell biology, organismal struc-ture, development, and ecology arecompared among related species toidentify their patterns of variation Thepatterns of similarity and dissimilarityare then used to test hypotheses ofrelatedness, and thereby to reconstructthe evolutionary tree that relates thespecies being studied The evolution-ary tree is then used to examinehypotheses of the evolutionary origins
of the diverse molecular, cellular,organismal, and populational proper-ties observed in the animal world.Clearly, the evolutionary sciences rely
on results of the experimental sciences
as a starting point Evolutionary ences include comparative biochem-istry, molecular evolution, comparativecell biology, comparative anatomy,comparative physiology, and phyloge-netic systematics
sci-Theories of Evolution and Heredity
We turn now to a specific tion of the two major paradigms thatguide zoological research today: Dar-win’s theory of evolution and the chro-mosomal theory of inheritance
considera-*Mayr, E 1982 The Growth of Biological Thought.
Cambridge, Harvard University Press, pp 67–71.
Trang 3614 PART 1 Introduction to the Living Animal
Darwin’s Theory
of Evolution
Darwin’s theory of evolution is nowover 130 years old (Chapter 6) Darwinarticulated the complete theory when
he published his famous book On the Origin of Species by Means of Natural Selection in England in 1859 (Figure 1-
12) Biologists today are frequentlyasked, “What is Darwinism?” and “Dobiologists still accept Darwin’s theory
of evolution?” These questions cannot
be given simple answers, because winism encompasses several different,although mutually compatible, theo-ries Professor Ernst Mayr of HarvardUniversity has argued that Darwinismshould be viewed as five major theo-ries.* These five theories have some-what different origins and differentfates and cannot be discussed accu-rately as if they were only a singlestatement The theories are (1) per-petual change, (2) common descent,
Dar-(3) multiplication of species, (4) alism, and (5) natural selection Thefirst three theories are generallyaccepted as having universal applica-tion throughout the living world Thetheories of gradualism and naturalselection are controversial among evo-lutionists, although both are stronglyadvocated by a large portion of theevolutionary community and areimportant components of the Darwin-ian evolutionary paradigm Gradualismand natural selection are clearly part ofthe evolutionary process, but theirexplanatory power might not be aswidespread as Darwin intended Legit-imate controversies regarding gradual-ism and natural selection often are mis-represented by creationists aschallenges to the first three theoriespresented above, although the validity
gradu-of those first three theories is stronglysupported by all relevant observations
1 Perpetual change This is the
basic theory of evolution on whichthe others are based It states thatthe living world is neither constantnor perpetually cycling, but isalways changing The properties oforganisms undergo transformationacross generations throughout time
This theory originated in antiquitybut did not gain widespread accep-tance until Darwin advocated it inthe context of his other four theo-ries “Perpetual change” is docu-mented by the fossil record, whichclearly refutes creationists’ claimsfor a recent origin of all livingforms Because it has withstoodrepeated testing and is supported
by an overwhelming number ofobservations, we now regard “per-petual change” as a scientific fact
2 Common descent The second
Darwinian theory, “commondescent,” states that all forms of lifedescended from a common ances-tor through a branching of lineages(Figure 1-13) The opposing argu-ment, that the different forms oflife arose independently anddescended to the present in linear,unbranched genealogies, has beenrefuted by comparative studies oforganismal form, cell structure, and
macromolecular structures ing those of the genetic material,DNA) All of these studies confirmthe theory that life’s history has thestructure of a branching evolution-ary tree, known as a phylogeny
(includ-Species that share relatively recentcommon ancestry have more simi-lar features at all levels than dospecies that have only an ancientcommon ancestry Much currentresearch is guided by Darwin’s the-ory of common descent towardreconstructing life’s phylogenyusing the patterns of similarity anddissimilarity observed amongspecies The resulting phylogenyserves as the basis for our taxo-nomic classification of animals(Chapter 10)
3 Multiplication of species
Dar-win’s third theory states that theevolutionary process produces
Figure 1-13
An early tree of life drawn in 1874 by the German biologist, Ernst Haeckel, who was strongly influenced by Darwin’s theory of common descent Many of the phylogenetic hypotheses shown in this tree, including the unilateral progression of evolution toward humans ( Menschen, top), have since been refuted.
Figure 1-12
Modern evolutionary theory is strongly identified with Charles Robert Darwin who, with Alfred Russel Wallace, provided the first credible explanation of evolution This photograph of Darwin was taken in 1854 when he was 45
years old His most famous book, On the Origin
of Species, appeared five years later.
*Mayr, E 1985 Chapter 25 in D Kohn, ed The
Dar-winian Heritage Princeton, Princeton University Press.
Trang 37CHAPTER 1 Life: Biological Principles and the Science of Zoology 15
Akiapolaau Nukupuu
Kauai akialoa
Maui parrotbill
Ou
Kona finch
Laysan finch
new species by the splitting andtransformation of older ones
Species are now generally viewed
as reproductively distinct tions of organisms that usually butnot always differ from each other
popula-in organismal form Once speciesare fully formed, interbreedingamong members of differentspecies does not occur Evolution-ists generally agree that the split-ting and transformation of lin-eages produces new species,although there is still much con-troversy concerning the details ofthis process (Chapter 6) and theprecise meaning of the term
“species” (Chapter 10) The study
of the historical processes thatgenerate new species guidesmuch active scientific research
4 Gradualism Gradualism states
that the large differences inanatomical traits that characterizedifferent species originate throughthe accumulation of many smallincremental changes over verylong periods of time This theory
is important because geneticchanges having very large effects
on organismal form are usuallyharmful to the organism It is pos-sible, however, that some geneticvariants that have large effects onthe organism are nonetheless suffi-ciently beneficial to be favored bynatural selection Therefore,although gradual evolution isknown to occur, it may notexplain the origin of all structuraldifferences that we observe amongspecies (Figure 1-14) Scientists arestill actively studying this question
5 Natural selection Natural
selec-tion, Darwin’s most famous ory, rests on three propositions
the-First, there is variation amongorganisms (within populations) foranatomical, behavioral, and physi-ological traits Second, the varia-tion is at least partly heritable sothat offspring tend to resembletheir parents Third, organismswith different variant forms leavedifferent numbers of offspring tofuture generations Variants that
permit their possessors most tively to exploit their environ-ments will preferentially surviveand be transmitted to future gen-erations Over many generations,favorable new traits will spreadthroughout the population Accu-mulation of such changes leads,over long periods of time, to theproduction of new organismal fea-tures and new species Naturalselection is therefore a creativeprocess that generates novel fea-tures from the small individualvariations that occur amongorganisms within a population.Natural selection explains whyorganisms are constructed to meet the demands of their environments,
(Figure 1-15) Adaptation is theexpected result of a process that accu-mulates the most favorable variantsoccurring in a population throughoutlong periods of evolutionary time.Adaptation was viewed previously asstrong evidence against evolution, andDarwin’s theory of natural selection
Trang 3816 PART 1 Introduction to the Living Animal
was therefore important for convincingpeople that a natural process, capable
of being studied scientifically, couldproduce new species The demonstra-tion that natural processes could pro-duce adaptation was important to theeventual acceptance of all five Darwin-ian theories
Darwin’s theory of natural tion faced a major obstacle when it wasfirst proposed: it lacked a theory ofheredity People assumed incorrectlythat heredity was a blending process,and that any favorable new variantappearing in a population thereforewould be lost The new variant arisesinitially in a single organism, and thatorganism therefore must mate with onelacking the favorable new trait Underblending inheritance, the organism’soffspring would then have only a di-luted form of the favorable trait Theseoffspring likewise would mate withothers that lack the favorable trait Withits effects diluted by half each genera-tion, the trait eventually would cease toexist Natural selection would be com-pletely ineffective in this situation
selec-Darwin was never able to counterthis criticism successfully It did notoccur to Darwin that hereditary factorscould be discrete and nonblending andthat a new genetic variant thereforecould persist unaltered from one gener-
ation to the next This principle is
known as particulate inheritance It
was established after 1900 with the covery of Gregor Mendel’s geneticexperiments, and it was eventuallyincorporated into what we now call the
dis-chromosomal theory of inheritance.
We use the term neo-Darwinism to
describe Darwin’s theories as modified
by incorporating this theory of tance
inheri-Mendelian Heredity and the Chromosomal Theory of Inheritance
The chromosomal theory of inheritance
is the foundation for current studies ofgenetics and evolution in animals(Chapters 5 and 6) This theory comesfrom the consolidation of research done
in the fields of genetics, which wasfounded by the experimental work ofGregor Mendel (Figure 1-16), and cellbiology
Genetic Approach
The genetic approach consists of ing or “crossing” populations of organ-isms that are true-breeding for contrast-ing traits, and then following thehereditary transmission of those traitsthrough subsequent generations “True-
mat-breeding” means that a populationmaintains across generations only one
of the contrasting states of a particularfeature when propagated in isolationfrom other populations
Gregor Mendel studied the mission of seven variable features ingarden peas, crossing populations thatwere true-breeding for alternative traits(for example, tall versus short plants) Inthe first generation (called the F1gener-ation, for “filial”), only one of the alter-native parental traits was observed;there was no indication of blending ofthe parental traits In the example, theoffspring (called F1 hybrids) formed bycrossing the tall and short plants weretall, regardless of whether the tall traitwas inherited from the male or thefemale parent These F1 hybrids wereallowed to self-pollinate, and bothparental traits were found among theiroffspring (called the F2 generation),although the trait observed in the F1
trans-hybrids (tall plants in this example) wasthree times more common than theother trait Again, there was no indica-tion of blending of the parental traits(Figure 1-17)
Mendel’s experiments showed thatthe effects of a genetic factor can bemasked in a hybrid individual, but thatthese factors were not physically alteredduring the transmission process He
Trang 39CHAPTER 1 Life: Biological Principles and the Science of Zoology 17
postulated that variable traits are fied by paired hereditary factors, which
speci-we now call “genes.” When gametes
(eggs or sperm) are produced, the twogenes controlling a particular featureare segregated from each other andeach gamete receives only one of them
Fertilization restores the paired tion If an organism possesses differentforms of the paired genes for a feature,only one of them is expressed in itsappearance, but both genes nonethe-less will be transmitted unaltered inequal numbers to the gametes pro-duced Transmission of these genes isparticulate, not blending Mendelobserved that the inheritance of onepair of traits is independent of theinheritance of other paired traits Wenow know, however, that not all pairs
condi-of traits are inherited independently condi-ofeach other Numerous studies, particu-
larly of the fruit fly, Dr osophila melanogaster, have shown that the
principles of inheritance discovered tially in plants apply also to animals
ini-Contributions of Cell Biology
Improvements in microscopes duringthe 1800s permitted cytologists tostudy the production of gametes bydirect observation of reproductive
Figure 1-16
A, Gregor Johann Mendel B, The monastery in
Brno, Czech Republic, now a museum, where Mendel carried out his experiments with garden peas.
Short males
Short males
Tall and short (3:1 ratio)
All tall
Trang 4018 PART 1 Introduction to the Living Animal
The Animal Rights Controversy
In recent years, the debate surrounding the use of animals to serve human needs has intensified Most controversial
of all is the issue of animal use in biomedical and behavioral research and
in the testing of commercial products.
A few years ago, Congress passed a series of amendments to the Federal Animal Welfare Act, a body of laws covering animal care in laboratories and other facilities These amendments have become known as the three R’s:
Reduction in the number of animals
needed for research; Refinement of
techniques that might cause stress or
suffering; Replacement of live animals
with simulations or cell cultures whenever possible As a result, the total number of animals used each year in research and in testing of commercial products has declined Developments in cellular and molecular biology also have contributed to a decreased use of animals for research and testing The animal rights movement, composed largely of vocal antivivisectionists, has created an awareness of the needs of animals used in research and has stimulated researchers to discover cheaper, more efficient, and more humane alternatives.
However, computers and culturing
of cells can simulate the effects on organismal systems of, for instance, drugs, only when the basic principles involved are well known When the principles themselves are being scrutinized and tested, computer modeling is not sufficient A recent report by the National Research Council concedes that although the search for alternatives to the use of animals in research and testing will continue, “the chance that alternatives will completely replace animals in the foreseeable future
is nil.” Realistic immediate goals, however, are reduction in number of animals used, replacement of mammals with other vertebrates, and refinement of experimental procedures to reduce discomfort of the animals being tested.
Medical and veterinary progress depends on research using animals.
Every drug and every vaccine developed
to improve the human condition has
been tested first on animals Research using animals has enabled medical science to eliminate smallpox and polio, and to immunize against diseases previously common and often deadly, including diphtheria, mumps, and rubella It also has helped to create treatments for cancer, diabetes, heart disease, and manic-depressive psychoses, and to develop surgical procedures including heart surgery, blood transfusions, and cataract removal.
AIDS research is wholly dependent on studies using animals The similarity of simian AIDS, identified in rhesus monkeys, to human AIDS has permitted the disease in monkeys to serve as a model for the human disease Recent work indicates that cats, too, may prove
to be useful models for the development
of an AIDS vaccine Skin grafting experiments, first done with cattle and later with other animals, opened a new era in immunological research with vast ramifications for treatment of disease in humans and other animals.
Research using animals also has
benefited other animals through the
development of veterinary cures The vaccines for feline leukemia and canine parvovirus were first introduced to other cats and dogs Many other vaccinations for serious diseases of animals were developed through research on animals: for example, rabies, distemper, anthrax, hepatitis, and tetanus No endangered species is used in general research (except to protect that species from total extinction) Thus, research using animals has provided enormous benefits to humans and other animals Still, much remains to be learned about treatment of diseases such as cancer, AIDS, diabetes, and heart disease, and research with animals will be required for this purpose Despite the remarkable benefits produced by research on animals, advocates of animal rights often present
an inaccurate and emotionally distorted picture of this research The ultimate goal of most animal rights activists, who have focused specifically on the use of animals in science rather than on the treatment of animals in all contexts, remains the total abolition of all forms
of research using animals The scientific
According to the U.S Department of Health and Human Services, animal research has helped extend our life expectancy by 20.8 years.