Evolution, Third Edition

Brief Contents......Page 6
Full Contents......Page 8
Preface......Page 23
Part one Introduction......Page 28
1 The Rise of Evolutionary Biology......Page 30
1.1 Evolution means change in living things by descent with modification......Page 31
1.2 Living things show adaptations......Page 32
1.3 A short history of evolutionary biology......Page 33
1.3.1 Evolution before Darwin......Page 34
1.3.2 Charles Darwin......Page 36
1.3.3 Darwin’s reception......Page 37
1.3.4 The modern synthesis......Page 41
Summary......Page 46
Study and review questions......Page 47
2 Molecular and Mendelian Genetics......Page 48
2.1 Inheritance is caused by DNA molecules, which are physically passed from parent to offspring......Page 49
2.2 DNA structurally encodes information used to build the body’s proteins......Page 50
2.3 Information in DNA is decoded by transcription and translation......Page 52
2.5 Mutational errors may occur during DNA replication......Page 54
2.6 Rates of mutation can be measured......Page 58
2.7 Diploid organisms inherit a double set of genes......Page 60
2.8 Genes are inherited in characteristic Mendelian ratios......Page 61
2.9 Darwin’s theory would probably not work if there was a non-Mendelian blending mechanism of heredity......Page 64
Further reading......Page 68
Study and review questions......Page 69
3 The Evidence for Evolution......Page 70
3.1 We distinguish three possible theories of the history of life......Page 71
3.2 On a small scale, evolution can be observed in action......Page 72
3.3 Evolution can also be produced experimentally......Page 74
3.4 Interbreeding and phenotypic similarity provide two concepts of species......Page 75
3.5 Ring “species” show that variation within a species can be extensive enough to produce a new species......Page 77
3.6 New, reproductively distinct species can be produced experimentally......Page 80
3.7 Small-scale observations can be extrapolated over the long term......Page 81
3.8 Groups of living things have homologous similarities......Page 82
3.9 Different homologies are correlated, and can be hierarchically classified......Page 88
3.10 Fossil evidence exists for the transformation of species......Page 91
3.11 The order of the main groups in the fossil record suggests they have evolutionary relationships......Page 92
3.12 Summary of the evidence for evolution......Page 93
3.14 Modern “scientific creationism” is scientifically untenable......Page 94
Further reading......Page 96
Study and review questions......Page 97
4 Natural Selection and Variation......Page 106
4.1 In nature, there is a struggle for existence......Page 107
4.2 Natural selection operates if some conditions are met......Page 109
4.3 Natural selection explains both evolution and adaptation......Page 110
4.4 Natural selection can be directional, stabilizing, or disruptive......Page 111
4.5 Variation in natural populations is widespread......Page 116
4.6 Organisms in a population vary in reproductive success......Page 120
4.7 New variation is generated by mutation and recombination......Page 122
4.8 Variation created by recombination and mutation is random with respect to the direction of adaptation......Page 123
Further reading......Page 125
Study and review questions......Page 126
Part two Evolutionary Genetics......Page 128
5 The Theory of Natural Selection......Page 130
5.1 Population genetics is concerned with genotype and gene frequencies......Page 131
5.2 An elementary population genetic model has four main steps......Page 132
5.3 Genotype frequencies in the absence of selection go to the Hardy–Weinberg equilibrium......Page 133
5.4 We can test, by simple observation, whether genotypes in a population are at the Hardy–Weinberg equilibrium......Page 137
5.5 The Hardy–Weinberg theorem is important conceptually, historically, in practical research, and in the workings of theoretical models......Page 138
5.6 The simplest model of selection is for one favored allele at one locus......Page 139
5.7.1 Industrial melanism in moths evolved by natural selection......Page 143
5.7.2 One estimate of the fitnesses is made using the rate of change in gene frequencies......Page 144
5.7.3 A second estimate of the fitnesses is made from the survivorship of the different genotypes in mark–recapture experiments......Page 146
5.7.4 The selective factor at work is controversial, but bird predation was probably influential......Page 147
5.8 Pesticide resistance in insects is an example of natural selection......Page 150
5.9 Fitnesses are important numbers in evolutionary theory and can be estimated by three main methods......Page 153
5.10 Natural selection operating on a favored allele at a single locus is not meant to be a general model of evolution......Page 155
5.11 A recurrent disadvantageous mutation will evolve to a calculable equilibrial frequency......Page 156
5.12.1 Selection can maintain a polymorphism when the heterozygote is fitter than either homozygote......Page 158
5.12.2 Sickle cell anemia is a polymorphism with heterozygous advantage......Page 159
5.13 The fitness of a genotype may depend on its frequency......Page 162
5.14.1 A subdivided set of populations have a higher proportion of homozygotes than an equivalent fused population: this is the Wahlund effect......Page 164
5.14.2 Migration acts to unify gene frequencies between populations......Page 165
5.14.4 A balance of selection and migration can maintain genetic differences between subpopulations......Page 167
Summary......Page 169
Further reading......Page 170
Study and review questions......Page 171
6 Random Events in Population Genetics......Page 172
6.1 The frequency of alleles can change at random through time in a process called genetic drift......Page 173
6.2 A small founder population may have a non-representative sample of the ancestral population’s genes......Page 175
6.3 One gene can be substituted for another by random drift......Page 177
6.5 Neutral drift over time produces a march to homozygosity......Page 180
6.6 A calculable amount of polymorphism will exist in a population because of neutral mutation......Page 185
6.7 Population size and effective population size......Page 186
Further reading......Page 188
Study and review questions......Page 189
7 Natural Selection and Random Drift in Molecular Evolution......Page 190
7.1 Random drift and natural selection can both hypothetically explain molecular evolution......Page 191
7.2 Rates of molecular evolution and amounts of genetic variation can be measured......Page 194
7.3 Rates of molecular evolution are arguably too constant for a process controlled by natural selection......Page 199
7.4 The molecular clock shows a generation time effect......Page 202
7.5.1 The “purely” neutral theory faces several empirical problems......Page 205
7.5.2 The nearly neutral theory of molecular evolution posits a class of nearly neutral mutations......Page 206
7.5.3 The nearly neutral theory can explain the observed facts better than the purely neutral theory......Page 208
7.5.4 The nearly neutral theory is conceptually closely related to the original, purely neutral theory......Page 209
7.6.1 More functionally constrained parts of proteins evolve at slower rates......Page 210
7.6.2 Both natural selection and neutral drift can explain the trend for proteins, but only drift is plausible for DNA......Page 212
7.7 Conclusion and comment: the neutralist paradigm shift......Page 213
7.8 Genomic sequences have led to new ways of studying molecular evolution......Page 214
7.8.1 DNA sequences provide strong evidence for natural selection on protein structure......Page 215
7.8.2 A high ratio of non-synonymous to synonymous changes provides evidence of selection......Page 216
7.8.3 Selection can be detected by comparisons of the dN/dS ratio within and between species......Page 219
7.8.4 The gene for lysozyme has evolved convergently in cellulose-digesting mammals......Page 221
7.8.5 Codon usages are biased......Page 222
7.8.6 Positive and negative selection leave their signatures in DNA sequences......Page 224
7.9 Conclusion: 35 years of research on molecular evolution......Page 225
Summary......Page 226
Further reading......Page 227
Study and review questions......Page 228
8 Two-locus and Multilocus Population Genetics......Page 229
8.1 Mimicry in Papilio is controlled by more than one genetic locus......Page 230
8.3 Mimicry in Heliconius is controlled by more than one gene, but they are not tightly linked......Page 232
8.5 Frequencies of haplotypes may or may not be in linkage equilibrium......Page 234
8.6 Human HLA genes are a multilocus gene system......Page 238
8.7 Linkage disequilibrium can exist for several reasons......Page 239
8.8 Two-locus models of natural selection can be built......Page 241
8.10 Selective sweeps can provide evidence of selection in DNA sequences......Page 245
8.11 Linkage disequilibrium can be advantageous, neutral, or disadvantageous......Page 247
8.12 Wright invented the influential concept of an adaptive topography......Page 249
8.13 The shifting balance theory of evolution......Page 251
Summary......Page 254
Further reading......Page 255
Study and review questions......Page 256
9 Quantitative Genetics......Page 257
9.1 Climatic changes have driven the evolution of beak size in one of Darwin’s finches......Page 258
9.2 Quantitative genetics is concerned with characters controlled by large numbers of genes......Page 261
9.3 Variation is first divided into genetic and environmental effects......Page 263
9.4 Variance of a character is divided into genetic and environmental effects......Page 266
9.5 Relatives have similar genotypes, producing the correlation between relatives......Page 269
9.6 Heritability is the proportion of phenotypic variance that is additive......Page 270
9.7 A character’s heritability determines its response to artificial selection......Page 271
9.8 Strength of selection has been estimated in many studies of natural populations......Page 275
9.9 Relations between genotype and phenotype may be non-linear, producing remarkable responses to selection......Page 277
9.10 Stabilizing selection reduces the genetic variability of a character......Page 280
9.11 Characters in natural populations subject to stabilizing selection show genetic variation......Page 281
9.12 Levels of genetic variation in natural populations are imperfectly understood......Page 282
9.13 Conclusion......Page 284
Summary......Page 285
Further reading......Page 286
Study and review questions......Page 287
Part three Adaptation and Natural Selection......Page 288
10 Adaptive Explanation......Page 290
10.1 Natural selection is the only known explanation for adaptation......Page 291
10.3 Natural selection can in principle explain all known adaptations......Page 294
10.4.1 In Darwin’s theory, no special process produces evolutionary novelties......Page 298
10.4.2 The function of an adaptation may change with little change in its form......Page 299
10.4.3 A new adaptation may evolve by combining unrelated parts......Page 300
10.5.1 Fisher proposed a model, and microscope analogy, to explain why the genetic changes in adaptive evolution will be small......Page 301
10.5.3 The genetics of adaptation is being studied experimentally......Page 303
10.6 Three main methods are used to study adaptation......Page 305
10.7.1 Adaptations may be imperfect because of time lags......Page 307
10.7.2 Genetic constraints may cause imperfect adaptation......Page 309
10.7.3 Developmental constraints may cause adaptive imperfection......Page 310
10.7.4 Historic constraints may cause adaptive imperfection......Page 316
10.7.6 Conclusion: constraints on adaptation......Page 319
10.8.1 The function of an organ should be distinguished from the effects it may have......Page 321
10.8.2 Adaptations can be defined by engineering design or reproductive fitness......Page 322
Summary......Page 323
Further reading......Page 324
Study and review questions......Page 326
11 The Units of Selection......Page 327
11.1 What entities benefit from the adaptations produced by selection?......Page 328
11.2.1 Segregation distortion benefits one gene at the expense of its allele......Page 329
11.2.2 Selection may sometimes favor some cell lines relative to other cell lines in the same body......Page 330
11.2.3 Natural selection has produced many adaptations to benefit organisms......Page 331
11.2.4 Natural selection working on groups of close genetic relatives is called kin selection......Page 333
11.2.5 Whether group selection ever produces adaptations for the benefit of groups has been controversial, though most biologists now think it is only a weak force in evolution......Page 336
11.2.6 Which level in the hierarchy of organization levels will evolve adaptations is controlled by which level shows heritability......Page 340
11.3 Another sense of “unit of selection” is the entity whose frequency is adjusted directly by natural selection......Page 341
11.4 The two senses of “unit of selection” are compatible: one specifies the entity that generally shows phenotypic adaptations, the other the entity whose frequency is generally adjusted by natural selection......Page 345
Summary......Page 346
Study and review questions......Page 347
12 Adaptations in Sexual Reproduction......Page 348
12.1.1 Sex has a 50% cost......Page 349
12.1.2 Sex is unlikely to be explained by genetic constraint......Page 350
12.1.3 Sex can accelerate the rate of evolution......Page 351
12.1.4 Is sex maintained by group selection?......Page 353
12.2.1 Sexual reproduction can enable females to reduce the number of deleterious mutations in their offspring......Page 355
12.2.2 The mutational theory predicts U>1......Page 356
12.2.3 Coevolution of parasites and hosts may produce rapid environmental change......Page 358
12.4.1 Sexual characters are often apparently deleterious......Page 362
12.4.2 Sexual selection acts by male competition and female choice......Page 363
12.4.3 Females may choose to pair with particular males......Page 364
12.4.4 Females may prefer to pair with handicapped males, because the male’s survival indicates his high quality......Page 366
12.4.5 Female choice in most models of Fisher’s and Zahavi’s theories is open ended, and this condition can be tested......Page 367
12.4.6 Fisher’s theory requires heritable variation in the male character, and Zahavi’s theory requires heritable variation in fitness......Page 368
12.4.7 Natural selection may work in conflicting ways on males and females......Page 370
12.4.8 Conclusion: the theory of sex differences is well worked out but incompletely tested......Page 371
12.5.1 Natural selection usually favors a 50:50 sex ratio......Page 372
12.5.2 Sex ratios may be biased when either sons or daughters disproportionately act as “helpers at the nest”......Page 374
12.6 Different adaptations are understood in different levels of detail......Page 376
Further reading......Page 377
Study and review questions......Page 378
Part four Evolution and Diversity......Page 380
13 Species Concepts and Intraspecific Variation......Page 382
13.1 In practice species are recognized and defined by phenetic characters......Page 383
13.2 Several closely related species concepts exist......Page 385
13.2.1 The biological species concept......Page 386
13.2.2 The ecological species concept......Page 388
13.2.3 The phenetic species concept......Page 389
13.3.1 Isolating barriers prevent interbreeding between species......Page 390
13.3.2 Sperm or pollen competition can produce subtle prezygotic isolation......Page 391
13.3.3 Closely related African cichlid fish species are prezygotically isolated by their color patterns, but are not postzygotically isolated......Page 392
13.4.1 Geographic variation exists in all species and can be caused by adaptation to local conditions......Page 394
13.4.2 Geographic variation may also be caused by genetic drift......Page 395
13.4.3 Geographic variation may take the form of a cline......Page 397
13.5 “Population thinking” and “typological thinking” are two ways of thinking about biological diversity......Page 398
13.6 Ecological influences on the form of a species are shown by the phenomenon of character displacement......Page 401
13.7 Some controversial issues exist between the phenetic, biological, and ecological species concepts......Page 402
13.7.1 The phenetic species concept suffers from serious theoretical defects......Page 403
13.7.2 Ecological adaptation and gene flow can provide complementary, or in some cases competing, theories of the integrity of species......Page 404
13.7.3 Both selection and genetic incompatibility provide explanations of reduced hybrid fitness......Page 408
13.8.1 The species category......Page 409
13.8.2 Categories below the species level......Page 410
13.8.3 Categories above the species level......Page 411
13.9 Conclusion......Page 412
Further reading......Page 413
Study and review questions......Page 415
14 Speciation......Page 416
14.2 A newly evolving species could theoretically have an allopatric, parapatric, or sympatric geographic relation with its ancestor......Page 417
14.3 Reproductive isolation can evolve as a by-product of divergence in allopatric populations......Page 418
14.3.1 Laboratory experiments illustrate how separately evolving populations of a species tend incidentally to evolve reproductive isolation......Page 419
14.3.2 Prezygotic isolation evolves because it is genetically correlated with the characters undergoing divergence......Page 421
14.3.3 Reproductive isolation is often observed when members of geographically distant populations are crossed......Page 422
14.4.1 The Dobzhansky–Muller theory is a genetic theory of postzygotic isolation, explaining it by interactions among many gene loci......Page 424
14.4.2 The Dobzhansky–Muller theory is supported by extensive genetic evidence......Page 426
14.4.3 The Dobzhansky–Muller theory has broad biological plausibility......Page 427
14.4.4 The Dobzhansky–Muller theory solves a general problem of “valley crossing” during speciation......Page 429
14.4.5 Postzygotic isolation may have ecological as well as genetic causes......Page 430
14.4.6 Postzygotic isolation usually follows Haldane’s rule......Page 431
14.6.1 Reproductive isolation may be reinforced by natural selection......Page 434
14.6.2 Preconditions for reinforcement may be short lived......Page 436
14.6.3 Empirical tests of reinforcement are inconclusive or fail to support the theory......Page 437
14.7 Some plant species have originated by hybridization......Page 440
14.8 Speciation may occur in non-allopatric populations, either parapatrically or sympatrically......Page 443
14.9.1 Parapatric speciation begins with the evolution of a stepped cline......Page 444
14.10.1 Sympatric speciation is theoretically possible......Page 446
14.10.2 Phytophagous insects may split sympatrically by host shifts......Page 447
14.11 The influence of sexual selection in speciation is one current trend in research......Page 448
14.12 Identification of genes that cause reproductive isolation is another current trend in research......Page 450
14.13 Conclusion......Page 452
Further reading......Page 454
Study and review questions......Page 457
15 The Reconstruction of Phylogeny......Page 458
15.1 Phylogenies express the ancestral relations between species......Page 459
15.2 Phylogenies are inferred from morphological characters using cladistic techniques......Page 460
15.3 Homologies provide reliable evidence for phylogenetic inference, and homoplasies provide unreliable evidence......Page 462
15.4 Homologies can be distinguished from homoplasies by several criteria......Page 465
15.5 Derived homologies are more reliable indicators of phylogenetic relations than are ancestral homologies......Page 466
15.6 The polarity of character states can be inferred by several techniques......Page 468
15.6.1 Outgroup comparison......Page 469
15.6.2 The fossil record......Page 470
15.7 Some character conflict may remain after cladistic character analysis is complete......Page 471
15.8 Molecular sequences are becoming increasingly important in phylogenetic inference, and they have distinct properties......Page 472
15.9.1 An unrooted tree is a phylogeny in which the common ancestor is unspecified......Page 474
15.9.2 One class of molecular phylogenetic techniques uses molecular distances......Page 475
15.9.3 Molecular evidence may need to be adjusted for the problem of multiple hits......Page 477
15.9.4 A second class of phylogenetic techniques uses the principle of parsimony......Page 480
15.9.5 A third class of phylogenetic techniques uses the principle of maximum likelihood......Page 482
15.10.1 Different molecules evolve at different rates and molecular evidence can be tuned to solve particular phylogenetic problems......Page 484
15.11 Several problems have been encountered in molecular phylogenetics......Page 486
15.11.2 The number of possible trees may be too large for them all to be analyzed......Page 487
15.11.3 Species in a phylogeny may have diverged too little or too much......Page 490
15.11.4 Different lineages may evolve at different rates......Page 491
15.11.5 Paralogous genes may be confused with orthologous genes......Page 492
15.11.6 Conclusion: problems in molecular phylogenetics......Page 493
15.12 Paralogous genes can be used to root unrooted trees......Page 494
15.13 Molecular evidence successfully challenged paleontological evidence in the analysis of human phylogenetic relations......Page 495
15.14 Unrooted trees can be inferred from other kinds of evidence, such as chromosomal inversions in Hawaiian fruitflies......Page 498
15.15 Conclusion......Page 501
Further reading......Page 502
Study and review questions......Page 504
16 Classification and Evolution......Page 506
16.2 There are phenetic and phylogenetic principles of classification......Page 507
16.3 There are phenetic, cladistic, and evolutionary schools of classification......Page 509
16.4 A method is needed to judge the merit of a school of classification......Page 510
16.5 Phenetic classification uses distance measures and cluster statistics......Page 511
16.6.1 Hennig’s cladism classifies species by their phylogenetic branching relations......Page 514
16.6.2 Cladists distinguish monophyletic, paraphyletic, and polyphyletic groups......Page 516
16.6.3 A knowledge of phylogeny does not simply tell us the rank levels in Linnaean classification......Page 518
16.7 Evolutionary classification is a synthesis of phenetic and phylogenetic principles......Page 520
16.8 The principle of divergence explains why phylogeny is hierarchical......Page 522
16.9 Conclusion......Page 524
Further reading......Page 525
Study and review questions......Page 526
17 Evolutionary Biogeography......Page 527
17.1 Species have defined geographic distributions......Page 528
17.3 Geographic distributions are influenced by dispersal......Page 531
17.4 Geographic distributions are influenced by climate, such as in the ice ages......Page 532
17.5 Local adaptive radiations occur on island archipelagos......Page 535
17.6 Species of large geographic areas tend to be more closely related to other local species than to ecologically similar species elsewhere in the globe......Page 538
17.7 Geographic distributions are influenced by vicariance events, some of which are caused by plate tectonic movements......Page 540
17.8 The Great American Interchange......Page 547
17.9 Conclusion......Page 552
Further reading......Page 553
Study and review questions......Page 555
Part five Macroevolution......Page 556
18 The History of Life......Page 558
18.1 Fossils are remains of organisms from the past and are preserved in sedimentary rocks......Page 559
18.2.1 Successive geological ages were first recognized by characteristic fossil faunas......Page 560
18.2.2 Geological time is measured in both absolute and relative terms......Page 561
18.3.1 The origin of life......Page 564
18.3.2 The origin of cells......Page 566
18.3.3 The origin of multicellular life......Page 568
18.4 The Cambrian explosion......Page 570
18.5 Evolution of land plants......Page 573
18.6.1 Colonization of the land......Page 575
18.6.2 Mammals evolved from the reptiles in a long series of small changes......Page 577
18.7.1 Four main classes of change occurred during hominin evolution......Page 580
18.7.2 Fossil records show something of our ancestors for the past 4 million years......Page 582
18.8 Macroevolution may or may not be an extrapolated form of microevolution......Page 585
Summary......Page 588
Further reading......Page 589
Study and review questions......Page 590
19 Evolutionary Genomics......Page 591
19.1 Our expanding knowledge of genome sequences is making it possible to ask, and answer, questions about the evolution of genomes......Page 592
19.2 The human genome documents the history of the human gene set since early life......Page 593
19.3 The history of duplications can be inferred in a genomic sequence......Page 594
19.4 Genome size can shrink by gene loss......Page 596
19.5 Symbiotic mergers, and horizontal gene transfer, between species influence genome evolution......Page 598
19.6 The X/Y sex chromosomes provide an example of evolutionary genomic research at the chromosomal level......Page 600
19.7 Genome sequences can be used to study the history of non-coding DNA......Page 602
19.8 Conclusion......Page 604
Further reading......Page 605
Study and review questions......Page 606
20 Evolutionary Developmental Biology......Page 607
20.2 The theory of recapitulation is a classic idea (largely discredited) about the relation between development and evolution......Page 608
20.3 Humans may have evolved from ancestral apes by changes in regulatory genes......Page 613
20.4 Many genes that regulate development have been identified recently......Page 614
20.5 Modern developmental genetic discoveries have challenged and clarified the meaning of homology......Page 615
20.6 The Hox gene complex has expanded at two points in the evolution of animals......Page 617
20.7 Changes in the embryonic expression of genes are associated with evolutionary changes in morphology......Page 618
20.8 Evolution of genetic switches enables evolutionary innovation, making the system more “evolvable”......Page 620
20.9 Conclusion......Page 622
Further reading......Page 623
Study and review questions......Page 624
21 Rates of Evolution......Page 625
21.1 Rates of evolution can be expressed in “darwins,” as illustrated by a study of horse evolution......Page 626
21.1.1 How do population genetic, and fossil, evolutionary rates compare?......Page 628
21.1.2 Rates of evolution observed in the short term can explain speciation over longer time periods in Darwin’s finches......Page 630
21.2 Why do evolutionary rates vary?......Page 631
21.3 The theory of punctuated equilibrium applies the theory of allopatric speciation to predict the pattern of change in the fossil record......Page 634
21.4.1 A satisfactory test requires a complete stratigraphic record and biometrical evidence......Page 637
21.4.2 Caribbean bryozoans from the Upper Miocene and Lower Pliocene show a punctuated equilibrial pattern of evolution......Page 638
21.4.4 Conclusion......Page 640
21.5 Evolutionary rates can be measured for non-continuous character changes, as illustrated by a study of “living fossil” lungfish......Page 641
21.6 Taxonomic data can be used to describe the rate of evolution of higher taxonomic groups......Page 644
Summary......Page 646
Study and review questions......Page 647
22 Coevolution......Page 648
22.1 Coevolution can give rise to coadaptations between species......Page 649
22.3.1 Coevolution between insects and plants may have driven the diversification of both taxa......Page 651
22.3.2 Two taxa may show mirror-image phylogenies, but coevolution is only one of several explanations for this pattern......Page 653
22.3.3 Cophylogenies are not found when phytophagous insects undergo host shifts to exploit phylogenetically unrelated but chemically similar plants......Page 655
22.3.4 Coevolution between plants and insects may explain the grand pattern of diversification in the two taxa......Page 657
22.5 Parasite–host coevolution......Page 658
22.5.1 Evolution of parasitic virulence......Page 660
22.5.2 Parasites and their hosts may have cophylogenies......Page 665
22.6 Coevolution can proceed in an “arms race”......Page 667
22.6.1 Coevolutionary arms races can result in evolutionary escalation......Page 669
22.7 The probability that a species will go extinct is approximately independent of how long it has existed......Page 672
22.8 Antagonistic coevolution can have various forms, including the Red Queen mode......Page 673
Summary......Page 675
Further reading......Page 676
Study and review questions......Page 677
23 Extinction and Radiation......Page 678
23.1 The number of species in a taxon increases during phases of adaptive radiation......Page 679
23.2 Causes and consequences of extinctions can be studied in the fossil record......Page 681
23.3.1 The fossil record of extinction rates shows recurrent rounds of mass extinctions......Page 683
23.3.2 The best studied mass extinction occurred at the Cretaceous–Tertiary boundary......Page 686
23.3.3 Several factors can contribute to mass extinctions......Page 688
23.4 Distributions of extinction rates may fit a power law......Page 690
23.5 Changes in the quality of the sedimentary record through time are associated with changes in the observed extinction rate......Page 692
23.6.1 Characters that evolve within taxa may influence extinction and speciation rates, as illustrated by snails with planktonic and direct development......Page 693
23.6.2 Differences in the persistence of ecological niches will influence macroevolutionary patterns......Page 699
23.6.3 When species selection operates, the factors that control macroevolution differ from the factors that control microevolution......Page 700
23.6.4 Forms of species selection may change during mass extinctions......Page 701
23.7.1 Taxonomic patterns through time can provide evidence about the cause of replacements......Page 704
23.7.2 Two bryozoan groups are a possible example of a competitive replacement......Page 705
23.7.3 Mammals and dinosaurs are a classic example of independent replacement, but recent molecular evidence has complicated the interpretation......Page 706
23.8 Species diversity may have increased logistically or exponentially since the Cambrian, or it may have increased little at all......Page 709
23.9 Conclusion: biologists and paleontologists have held a range of views about the importance of mass extinctions in the history of life......Page 712
Summary......Page 713
Further reading......Page 714
Study and review questions......Page 716
Glossary......Page 717
Answers to Study and Review Questions......Page 725
References......Page 734
Index......Page 768
Color Plates
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