Contents
1 Introduction: competition theory past and present I
1.1 Ashorthistory 1
1.2 Theneedforresourcesincompelilionlheory 3
1.3 TheLotka-Volterramodel 4
1.4 Thefirstrevivalofcompetitiontheory 7
1.5 Recentcompetitiontheory 8
1.6 Generalthemesofthisbook 9
1.7 Necessarybackgroundandalookahead 12
2 Defininganddescribingcompetition 13
2.1 Introduction 13
2.2 Historical definitions of competition 14
2.3 What should the definition be? 22
2.4 Implications of the definition 24
2.5 Competition within the framework of food webs 29
3 Measuring and describing competition: a
consumer-resource framework 33
3.1 The measurement of competition (and other interactions) 33
3.2 Methods of measuring and describing competition 36
3.3 Arguments against resource-based definitions and models 40
3.4 MacArthur’s connection of LV to consumer-resource models 42
3.5 What do coexistence and exclusion mean? 47
3.6 What distinguishes a single resource from others? 49
3.7 Functional forms for the model components 49
3.7.1 Resource growth 52
3.7.2 Consumer functional responses 53
3.7.3 Consumer numerical responses 56
3.8 Analysis of models of competition 58
3.9 Summary 61
4 Competition theory: its present state 63
4.1 Introduction 63
4.2 Questions for assessing recent influential theory 64
4.3 Choosing articles to represent current competition theory 66
4.4 Forgotten results in ‘modern competition theory' 70
4.5 Why the Lotka-Volterra and MacArthur models are insufficient 72
4.6 Reasons for including resource dynamics 74
4.7 Appendix: Problematic features in the focal articles 75
5 Understanding intraspecific and apparent competition 79
5.1 Introduction 79
5.2 Intraspecific competition 80
5.2.1 The definition and mechanism of intraspecific
competition 81
5.2.2 Describing, measuring, and modelling intraspecific
competition 82
5.2.3 Models of density dependence 86
5.2.4 One-consumer-multi-resource systems 93
5.2.5 A more mechanistic approach to density dependence 101
5.3 Apparentcompetition 101
6 The negativity, constancy, and continuity of
competitive effects 109
6.1 Introduction 109
6.2 Resource extinction and quasi-extinction in MacArthur's model 111
6.3 Consequences of non-logistic resource growth 122
6.4 Consequences of nonlinear functional responses 125
6.4.1 Effects of nonlinear functional responses on consumer
competition in systems with stable equilibria 126
6.4.2 Interactions in unstable systems with type II responses 132
6.5 Interdependenceofcompetitiveeffectswithmoreconsumers 137
6.6 Other neglected aspects of consumer-resource models 138
7 Resource use and the strength of
interspecific competition 143
7.1 Theory regarding the strength of competition 143
7.1.1 Theory from the early 1970s 144
7.1.2 Early questioning of MacArthur's limiting similarity 147
7.1.3 Recent and potential future theory on overlap and
competition 149
7.1.4 Continued use of outdated similarity-competition
relationships 153
7.2 Laboratorystudiesofcompetition 154
7.3 Fieldstudiesofcompetition 155
7.3.1 Ahistoricalreview 156
7.3.2 An illustrative example: competition between hermit
crabs 157
7.3.3 Currentstatusoffieldstudiesofcompetition 159
7.4 Doescompetitiveneutralityoccur? 160
7.5 Interspecificcompetitioninafoodwebcontext 162
7.6 Competition between species in theory and reality 169
8 Competition in seasonal environments: temporal overlap 171
8.1 Introduction 171
| 8.1.1 | A brief history of work on seasonal competition | 172 | |
| 8.1.2 | Aspects of seasonal variation in competition treated here | 174 | |
| 8.1.3 | Why are the dynamics of seasonal systems important? | 175 | |
| 8.2 | A modelling framework and a seasonal MacArthur system | 176 | |
| 8.2.1 | General features of the models | 176 | |
| 8.2.2 | Resource lags and mutual invasibility of MacArthur systems | 178 | |
| 8.2.3 | Coexistence in a 2-consumer MacArthur system | 184 | |
| 8.2.4 | How robust and representative is the example? | 188 | |
| 8.2.5 | Coexistence of a seasonal and an aseasonal consumer | 189 | |
| 8.2.6 | A more complete description of seasonal interactions | 192 | |
| 8.2.7 | Seasonality resource conversion efficiency, b | 195 | |
| 8.2.8 | A 3-consumer system with variation in c | 197 | |
| 8.2.9 | A 2-resource system with temporal and non-temporal partitioning | 199 | |
| 8.3 | Competition in other 2-consumer-1-resource models | 200 | |
| 8.3.1 | Systems with abiotic resources | 201 | |
| 8.3.2 | Biotic resources with type II functional responses | 203 | |
| 8.3.3 | Abiotic resources with type II functional responses | 204 | |
| 8.4 | Discussion | 204 | |
9 Relative nonlinearity and seasonality 209
9.1 Introduction 209
9.2 Inherently unstable consumer-resource interactions 210
9.3 Differencesinnonlinearitywithseasonalresourcegrowth 213
9.4 Differences in the nonlinearity of numerical responses 222
| 9.5 | Other types of environmental variation | 225 |
| 9.5.1 Nonlinear numerical responses | 225 | |
| 9.5.2 Nonlinear functional responses | 226 | |
| 9.5.3 Remaining unknowns | 229 | |
| 9.6 | Systems with two or more resources | 230 |
| 9.7 | Discussion | 230 |
10 Consumersandresourcesinspace 233
10.1 Thenatureofspatialcompetition 233
10.2 Ahistoryofmetapopulationcompetitionmodels 237
10.3 Spaceandtheglobalshapeofintraspecificcompetition 238
10.4 Randommovementandcoexistence 241
10.4.1 Competition when only one trophic level moves 242
10.4.2 Competition with mobile consumers and interference
competition 244
10.5 Adaptive movements and their effects on competition 245
10.5.1 Generalaspectsofadaptivemovement 245
10.5.2 The shape of competition under adaptive consumer
movement 247
10.5.3 Adaptive movement by the resource 251
10.6 Adaptive movement of both species 253
10.7 Extendingourcurrentunderstandingofspatialcompetition 255
Il Evolution and its ecological consequences 257
11.1 Evolution’s many effects on interspecific competition 257
11.2 A brief history of work on the evolutionary responses to competition 261
11.2.1 Empirical studies of competitive coevolution 261
11.2.2 A history of theoretical models of competitive
coevolution 262
11.3 A simplified approach to evolution 265
11.4 Examples of non-standard questions and outcomes 267
11.4.1 Evolution in the resource population(s) 267
11.4.2 Evolution with imperfectly or non-substitutable
resources 268
11.4.3 Evolution of other consumer parameters 270
11.5 Evolutionofapparentcompetitors 270
11.6 Evolution with both exploitative and interference competition 272
11.7 Evolution of competitors in a food web context 273
11.8 Evolution and coexistence: current theory and the future 274
12 Overview 277
12.1 Arangeofviewpointsontheory
277
12.2 Theory's roles in ecology and competition 280
12.2.1 Thegoalsoftheory 280
12.2.2 Therelationshipbetweentheoryandexperiment 281
12.2.3 Whatwillamorecomprehensivetheorylooklike? 282
12.3 Omitting intermediate entities in models of indirect interactions 283
12.4 Important aspects of consumer-resource relationships 285
12.5 Foodwebstructureanditsinfluenceoncompetition 287
12.6 Forcesthathavebiasedresearchoncompetition 288
12.7 Conclusions 290
References 295
Index 321