Evolution__3rd_Edition

viii Full Contents
3.5 Ring “species” show that the variation within a species can be
extensive enough to produce a new species 50
3.6 New, reproductively distinct species can be produced experimentally 53
3.7 Small-scale observations can be extrapolated over the long term 54
3.8 Groups of living things have homologous similarities 55
3.9 Different homologies are correlated, and can be hierarchically classified 61
3.10 Fossil evidence exists for the transformation of species 64
3.11 The order of the main groups in the fossil record suggests they have
evolutionary relationships 65
3.12 Summary of the evidence for evolution 66
3.13 Creationism offers no explanation of adaptation 67
3.14 Modern “scientific creationism” is scientifically untenable 67
Summary Further reading Study and review questions
4. Natural Selection and Variation 71
4.1 In nature, there is a struggle for existence 72
4.2 Natural selection operates if some conditions are met 74
4.3 Natural selection explains both evolution and adaptation 75
4.4 Natural selection can be directional, stabilizing, or disruptive 76
4.5 Variation in natural populations is widespread 81
4.6 Organisms in a population vary in reproductive success 85
4.7 New variation is generated by mutation and recombination 87
4.8 Variation created by recombination and mutation is random
with respect to the direction of adaptation 88
Summary Further reading Study and review questions
PART 2. EVOLUTIONARY GENETICS 93
5. The Theory of Natural Selection 95
5.1 Population genetics is concerned with genotype and gene frequencies 96
5.2 An elementary population genetic model has four main steps 97
5.3 Genotype frequencies in the absence of selection go to the Hardy–
Weinberg equilibrium 98
5.4 We can test, by simple observation, whether genotypes in a population
are at the Hardy–Weinberg equilibrium 102
5.5 The Hardy–Weinberg theorem is important conceptually,
historically, in practical research, and in the workings of
theoretical models 103
5.6 The simplest model of selection is for one favored allele at one locus 104
5.7 The model of selection can be applied to the peppered moth 108
5.7.1 Industrial melanism in moths evolved by natural selection 108
5.7.2 One estimate of the fitnesses is made using the rate of change
in gene frequencies 109
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