1;Title Page;3 2;Copyright Page;4 3;Table of Contents;5 4;Dedication;12 5;Preface;13 6;List of figures;14 7;List of tables;17 8;List of abbreviations and acronyms;18 9;1 Local-scale patterns in species richness;19 9.1;1.1 Local-scale trends in species richness;19 9.2;1.2 What is species richness?;19 9.3;1.3 What is meant by "local" variations in species richness?;21 9.4;1.4 Local-scale patterns are most noticeable in organisms that don't move around much;22 9.5;1.5 A related and important question: How do species coexist anywhere?;22 9.6;1.6 Different scales of species richness, from local to geographical;32 9.7;1.7 A varied environment tends to allow more species in;34 9.8;1.8 Using models to validate the logic of the role of disturbance in allowing coexistence;39 9.9;1.9 Do humpback curves really occur along disturbance gradients?;41 9.10;1.10 Grime and Tilman: disturbance creates other sorts of opportunities for coexistence, and variation in levels of disturbance affects these opportunities;43 9.11;1.11 When strategies mix-the humpback curve with succession, after a disturbance;44 9.12;1.12 The "other" humpback curve: along gradients in nutrient levels;45 9.13;1.13 Species richness is a balancing act between the effects of disturbance and nutrients;51 9.14;1.14 Why hasn't a humpbacked diversity curve been found for animals?;53 9.15;1.15 A quite different explanation for humpbacked diversity curves in plants, in relation to soil fertility;55 9.16;1.16 "Poisoned" and "extreme" environments are usually poor in species;58 9.17;1.17 Mountain-scale patterns in species richness;59 9.18;1.18 Patterns of species richness with depth in the oceans;62 9.19;1.19 Some conclusions about local-scale patterns in species richness;63 10;2 The Holy Grail of ecology: Latitudinal gradients;65 10.1;2.1 Latitudinal trends;65 10.2;2.2 The discovery of latitudinal trends;66 10.3;2.3 Explaining latitudinal gradients;73 10.4;2.4 Non-equilibrium theories: species richness can just keep on rising;78 10.4.1;2.4.1 The effects of ice ages;78 10.4.2;2.4.2 "The tropics are more benign";82 10.4.2.1;2.4.2.1 Are the tropics only more "benign" because most groups evolved in a past warmer world?;84 10.4.2.2;2.4.2.2 Do species "fall into" the tropics?;86 10.4.2.3;2.4.2.3 The mid-domain effect: Is the latitudinal gradient just the sum of chance overlap of ranges?;93 10.4.2.4;2.4.2.4 Are species originating more easily and more often at lower latitudes?;95 10.4.3;2.4.3 A general test of the disequilibrium theories: Has the build-up of species richness continued over time?;97 10.5;2.5 Equilibrium theories: there is a lid on species richness that is higher in the low latitudes;99 10.5.1;2.5.1 The tropics are just bigger;99 10.5.2;2.5.2 More energy, more food in warmer climates: the "speciesenergy hypothesis";99 10.5.3;2.5.3 More strongly seasonal environments mean less chance of occupying a narrow, specialized niche;103 10.5.4;2.5.4 More specialized enemies of plants mean more species can exist side by side at lower latitudes (the Janzen-Connell hypothesis);105 10.5.5;2.5.5 The latitudinal gradient is produced by a balance between growth and disturbance;110 10.6;2.6 The pros and cons of the various theories for latitudinal gradients;112 11;3 Deep time and mass extinctions;114 11.1;3.1 The depth of time;114 11.2;3.2 Species richness can change on a range of time scales;115 11.3;3.3 Sampling the past: the fossil record and species richness;115 11.4;3.4 The broadest scale picture of biological richness, since the beginning of life on Earth;117 11.5;3.5 What caused the sudden initial increase in diversity 540 Myr ago?;122 11.5.1;3.5.1 What could have caused the explosion of animal life after 600 Myr ago?;123 11.5.2;3.5.2 Is the Cambrian Explosion just an effect of better preservation?;124 11.6;3.6 How many species have ever existed?;125 11.7;3.7 Background extinction;127 11.7.1;3.7.1 The causes of background extinction;127 11.8;3.8 Mass extinctions;130 11.9;3.9 The main m