An Introduction to Behavioural Ecology

John R. Krebs FRS is Principal of Jesus College and Professor in the Department of Zoology at the University of  Oxford, and a member of the House of Lords.

Stuart West is Professor of Evolutionary Biology in the Department of Zoology at the University of Oxford.

Acknowledgements xiii

1 Natural Selection, Ecology and Behaviour 1

Watching and wondering 1

Natural selection 5

Genes and behaviour 6

Selfish individuals or group advantage? 11

Phenotypic plasticity: climate change and breeding times 18

Behaviour, ecology and evolution 21

Summary 22

Further reading 22

Topics for discussion 23

2 Testing Hypotheses in Behavioural Ecology 24

The comparative approach 25

Breeding behaviour of gulls in relation to predation risk 26

Social organization of weaver birds 28

Social organization in African ungulates 30

Limitations of early comparative studies 31

Comparative approach to primate ecology and behaviour 33

Using phylogenies in comparative analysis 37

The comparative approach reviewed 45

Experimental studies of adaptation 46

Summary 49

Further reading 50

Topics for discussion 51

3 Economic Decisions and the Individual 52

The economics of carrying a load 52

The economics of prey choice 59

Sampling and information 62

The risk of starvation 63

Environmental variability, body reserves and food storing 65

Food storing birds: from behavioural ecology to neuroscience 66

The evolution of cognition 71

Feeding and danger: a trade-off 73

Social learning 75

Optimality models and behaviour: an overview 79

Summary 81

Further reading 82

Topics for discussion 82

4 Predators versus Prey: Evolutionary Arms Races 83

Red Queen evolution 83

Predators versus cryptic prey 86

Enhancing camouflage 92

Warning colouration: aposematism 95

Mimicry 100

Trade-offs in prey defences 103

Cuckoos versus hosts 105

Summary 113

Further reading 114

Topics for discussion 114

5 Competing for Resources 116

The Hawk–Dove game 116

Competition by exploitation: the ideal free distribution 119

Competition by resource defence: the despotic distribution 123

The ideal free distribution with unequal competitors 123

The economics of resource defence 126

Producers and scroungers 130

Alternative mating strategies and tactics 131

ESS thinking 142

Animal personalities 143

Summary 144

Further reading 145

Topics for discussion 146

6 Living in Groups 147

How grouping can reduce predation 148

How grouping can improve foraging 159

Evolution of group living: shoaling in guppies 163

Group size and skew 164

Group decision making 169

Summary 177

Further reading 177

Topics for discussion 178

7 Sexual Selection, Sperm Competition and Sexual Conflict 179

Males and females 180

Parental investment and sexual competition 182

Why do females invest more in offspring care than do males? 184

Evidence for sexual selection 186

Why are females choosy? 189

Genetic benefits from female choice: two hypotheses 194

Testing the hypotheses for genetic benefits 196

Sexual selection in females and male choice 201

Sex differences in competition 204

Sperm competition 205

Constraints on mate choice and extra-pair matings 208

Sexual conflict 209

Sexual conflict: who wins? 216

Chase-away sexual selection 218

Summary 220

Further reading 221

Topics for discussion 221

8 Parental Care and Family Conflicts 223

Evolution of parental care 223

Parental investment: a parent’s optimum 227

Varying care in relation to costs and benefits 229

Sexual conflict 232

Sibling rivalry and parent–offspring conflict: theory 238

Sibling rivalry: evidence 240

Parent–offspring conflict: evidence 243

Brood parasites 249

Summary 252

Further reading 252

Topics for discussion 253

9 Mating Systems 254

Mating systems with no male parental care 254

Mating systems with male parental care 264

A hierarchical approach to mating system diversity 279

Summary 280

Further reading 281

Topics for discussion 281

10 Sex Allocation 282

Fisher’s theory of equal investment 285

Sex allocation when relatives interact 286

Sex allocation in variable environments 296

Selfish sex ratio distorters 304

Summary 305

Further reading 305

Topics for discussion 306

11 Social Behaviours: Altruism to Spite 307

Kin selection and inclusive fitness 308

Hamilton’s rule 313

How do individuals recognize kin? 318

Kin selection doesn’t need kin discrimination 322

Selfish restraint and kin selection 325

Spite 327

Summary 331

Further reading 332

Topics for discussion 333

12 Cooperation 334

What is cooperation? 334

Free riding and the problem of cooperation 336

Solving the problem of cooperation 337

Kin selection 339

Hidden benefits 341

By-product benefit 341

Reciprocity 345

Enforcement 350

A case study – the Seychelles Warbler 354

Manipulation 356

Summary 358

Further reading 358

Topics for discussion 359

13 Altruism and Conflict in the Social Insects 360

The social insects 360

The life cycle and natural history of a social insect 364

The economics of eusociality 366

The pathway to eusociality 366

The haplodiploidy hypothesis 367

The monogamy hypothesis 371

The ecological benefits of cooperation 375

Conflict within insect societies 379

Conflict over the sex ratio in the social hymenoptera 379

Worker policing in the social hymenoptera 386

Superorganisms 389

Comparison of vertebrates with insects 390

Summary 392

Further reading 392

Topics for discussion 393

14 Communication and Signals 394

The types of communication 395

The problem of signal reliability 396

Indices 397

Handicaps 405

Common interest 411

Human language 416

Dishonest signals 417

Summary 421

Further reading 422

Topics for discussion 423

15 Conclusion 424

How plausible are our main premises? 424

Causal and functional explanations 436

A final comment 438

Summary 441

Further reading 441

References 442

Index 489

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