Invertebrates in Hot and Cold Arid Environments

1 The Climate of Arid Environments.- 1.1 Subtropical and Temperate Deserts.- 1.1.1 Definitions.- 1.1.2 The Distribution of Deserts.- 1.1.3 Microclimate.- 1.2 Polar Deserts.- 1.2.1 The Arctic.- 1.2.2 The Antarctic.- 1.2.3 Microclimate.- 1.3 The Limitation of Water in Antarctic Terrestrial Ecosystems.- 1.3.1 Latitudinal Variations.- 1.3.2 Microclimatic Variations.- 1.4 Conclusions.- 2 The Fauna of Hot and Cold Arid Deserts.- 2.1 The Diversity of Hot Desert Invertebrates.- 2.1.1 Introduction.- 2.1.2 Soil Fauna: Microarthropods and Nematodes.- 2.1.3 Ants and Termites.- 2.1.4 Herbivores.- 2.1.4 Detritivorous Macroarthropods.- 2.1.6 Necrophagous and Coprophagous Arthropods.- 2.1.7 Predaceous Arthropods.- 2.2 The Fauna of Polar Regions.- 2.2.1 Introduction.- 2.2.2 Nematodes.- 2.2.3 Tardigrades.- 2.2.4 Rotifers.- 2.2.5 Other Invertebrates.- 2.2.6 Terrestrial Arthropods.- 2.3 Comparison of Hot and Cold Arid Environments.- 3 Tolerance to Arid Conditions in Terrestrial Arthropods.- 3.1 Microarthropods.- 3.1.1 Alpine Species.- 3.1.2 Polar Species.- 3.2 Coleoptera.- 3.2.1 Alpine Species.- 3.2.2 Polar Species.- 3.2.3 Tropical and Temperate Lowland Species.- 3.3 Other Terrestrial Arthropods.- 3.3.1 From Lowland Deserts.- 3.3.2 Alpine Millipedes.- 3.4 Conclusions.- 4 The Physiology of Tolerance to Desiccation.- 4.1 Introduction.- 4.2 Evaporative Water Losses.- 4.2.1 Beetles.- 4.2.2 Scorpions.- 4.3 The Cuticula of Terrestrial Arthropods.- 4.3.1 Structure.- 4.3.2 Restriction of Water Loss.- 4.3.3 Cuticular Lipids.- 4.3.4 Desert Arthropods.- 4.3.5 Evaporative Cooling.- 4.4 Water Absorption.- 4.4.1 The Hindgut of Insects.- 4.4.2 The Cryptonephridial System.- 4.4.3 Water Absorption in Other Terrestrial Arthropods.- 4.5 Osmoregulation.- 4.5.1 Occurrence in Different Taxa.- 4.5.2 Desert Tenebrionids.- 4.5.3 Alpine Beetles.- 4.6 Conclusions.- 5 Anhydrobiosis in Terrestrial Invertebrates.- 5.1 Introduction.- 5.2 Nematodes.- 5.2.1 Tolerance to Desiccation.- 5.2.2 Rates of Dehydration.- 5.2.3 Nematodes from Hot Deserts.- 5.2.4 Antarctic Nematodes.- 5.2.5 Accumulation of Trehalose.- 5.3 Tardigrades.- 5.3.1 Tun Formation.- 5.3.2 Ecological Implications.- 5.3.3 Accumulation of Trehalose.- 5.3.4 Recovery from Anhydrobiosis.- 5.4 Rotifers.- 5.5 Terrestrial Arthropods.- 5.5.1 Collembola.- 5.5.2 Chironomid Midges.- 5.6 Biochemical Aspects of Anhydrobiosis.- 5.7 Conclusions.- 6 Behavioural Adaptations.- 6.1 Arthropods from Hot Deserts.- 6.1.1 Introduction.- 6.1.2 Burrowing.- 6.1.3 Circadian and Seasonal Rhythms.- 6.1.4 Thermoregulation.- 6.2 Polar and Alpine Terrestrial Arthropods.- 6.2.1 Introduction.- 6.2.2 Mating and Oviposition.- 6.2.3 Microarthropods.- 6.2.4 Behavioural Thermoregulation.- 6.2.5 Avoidance of Heat and Cold by Alpine Tropical Arthropods.- 7 Phenological Adaptations.- 7.1 Life Cycles.- 7.1.1 Hot Desert Invertebrates.- 7.1.2 Polar Species.- 7.1.3 Alpine Species.- 7.1.4 Conclusions.- 7.2 Diapause and Quiescence.- 7.2.1 Introduction.- 7.2.2 Principle Features of Diapause.- 7.2.3 Dormancy in Tropical Insects.- 7.2.4 Dormancy in Polar Species.- 7.2.5 Conclusions.- 8 Water Balance During Overwintering.- 8.1 Introduction.- 8.2 Choice of Overwintering Sites.- 8.2.1 Environmental Factors.- 8.2.2 Cues for Overwintering.- 8.2.3 Anaerobiosis.- 8.3 Moisture Content of Overwintering Sites.- 8.3.1 Lack of Fluid Water.- 8.3.2 Water Vapour Pressure in Frozen Habitats.- 8.3.3 Longevity and Saturation Deficit.- 8.4 Inoculative Freezing.- 8.4.1 Contact with Ice and Inoculation.- 8.4.2 Protection Against Inoculative Freezing.- 8.5 The Effect of Dehydration on Cold Hardiness.- 8.6 Conclusions.- 9 Cold Hardiness in Terrestrial Arthropods.- 9.1 Introduction.- 9.2 Concepts of Cold Hardiness.- 9.2.1 Definition of Important Concepts.- 9.3 Freeze Susceptible Species.- 9.3.1 The Importance of Supercooling.- 9.3.2 Supercooling Capacity in Microarthropods.- 9.3.3 Removal of Ice-Nucleating Agents.- 9.3.4 Seasonal Changes.- 9.3.5 Gut Content and Ice-Nucleating Agents.- 9.3.6 Low Molecular Weight Cryoprotectant Substances.- 9.3.7 Thermal Hysteresis Proteins.- 9.3.8 Cryoprotectants in Alpine and Polar Microarthropods.- 9.4 Freeze Tolerant Species.- 9.4.1 Why is Freezing Injurious?.- 9.4.2 The Occurence of Freeze Tolerance in Insects.- 9.4.3 Polar and alpine insects.- 9.4.4 Variations in the Degree of Freeze Tolerance.- 9.4.5 Ice Nucleation in Freeze Tolerant Species.- 9.4.6 Cryoprotectant Substances.- 9.5 Freeze Tolerance Versus Freeze Avoidance.- 10 Hot Desert Arthropods at Low Temperatures.- 10.1 Preadaptation to Cold.- 10.2 Cold Hardiness of Different Taxa.- 10.2.1 Scorpions.- 10.2.2 Centipedes.- 10.2.3 Spiders.- 10.2.4 Insects.- 10.3 Conclusions.- 11 Cold Tolerance in “Lower” Invertebrates.- 11.1 Nematodes.- 11.1.1 Strategies of Cold Hardiness.- 11.1.2 Antarctic Nematodes.- 11.1.3 Freeze Tolerance During Anhydrobiosis.- 11.1.4 Freeze Tolerance or Freeze Avoidance?.- 11.2 Tardigrades.- 11.2.1 Freezing in Liquid Gases.- 11.2.2 Freezing at Environmental Temperatures.- 11.2.3 Antarctic Tardigrades.- 11.3 Rotifers.- 11.4 Lumbricid Earthworms.- 11.4.1 Effect of Dehydration.- 11.4.2 Long Term Survival.- 11.4.3 A Protective Dehydration Mechanism.- 11.5 Conclusions.- 12 Summary and Concluding Remarks.- 12.1 Deserts.- 12.2 The Fauna.- 12.3 Behaviour.- 12.4 Life Cycles.- 12.5 Terrestrial Arthropods and Aridity.- 12.6 Cold Hardiness.- 12.6.1 Terrestrial Arthropods.- 12.6.2 Tardigrades and Nematodes.- 12.6.3 Lumbricid Earthworms.- 12.7 Combined Tolerance of Cold and Drought.- 12.8 Anhydrobiosis.- References.