When survival is challenged by the cold, animals react by employing both behavioral and physiological solutions. Depending on the magni­ tude of the cold stress and the nature of the adjustment, simple avoidance or sophisticated capacity or resistance compensations may be used. Thus, migration, shelter seeking, metabolic and insulative compen­ sation, torpor, and freezing avoidance and tolerance are successful tac­ tics used by diverse groups of animals. To understand and appreciate the benefits of these tactics, it is necessary to examine not only the well being of the whole animal but also their basic underlying mechanisms. In ad­ dition, it is also of fundamental importance to grasp how seasonal cold affects the survivorship and reproductive success of populations when confronted by a general reduction in primary productivity and an elevated energy cost for maintenance (e. g. in endotherms). In this regard, a synthetic overview which integrates aspects of cell biology, biochem­ istry, physiology, neurobiology, behavior, and population biology should be a fruitful approach in providing a holistic understanding on how animals adapt to cold. The present volume is an attempt to achieve such an overview; its objective is to provide a depth and breadth of coverage that is essential to a full appreciation of animal adaptation to cold. It is the hope of the contributing authors that this book will serve as an effective reference text for all senior undergraduate and graduate students as well as research scientists with an interest in cold physiology.

1 Cold Adaptation in Ectotherms: Regulation of Membrane Function and Cellular Metabolism.- 1 Introduction.- 2 Homeoviscous Adaptation to Temperature in Ecotherms.- 3 Adaptations in the Rates and Patterns of Cellular Energy Metabolism.- 4 Conclusions.- References.- 2 Freeze Tolerance and Freeze Avoidance in Ectotherms.- 1 Introduction.- 2 Low Temperature and Freezing.- 3 Freeze Avoidance.- 4 Freeze Tolerance.- 5 The Choice of Freeze Tolerance Versus Freeze Avoidance.- References.- 3 Biochemical Mechanisms and Control of Cold-Induced Cellular Thermogenesis in Placental Mammals.- 1 Introduction.- 2 "Categories" of Thermogenesis.- 3 Acute Cold Exposure.- 4 Sustained Cold Exposure.- 5 Seasonal Changes in NST Capacity.- 6 Conclusion.- References.- 4 Neurophysiological Aspects of Thermoregulation.- 1 Introduction.- 2 Whole Body Thermoregulatory Responses.- 3 Sensitivity of Neurons Involved in Temperature Regulation.- 4 Neuronal Integration of Central and Peripheral Thermal Signals.- 5 Role of Afferent Input in Determining Neuronal Populations.- 6 Neural Mechanisms of Cold Adaptation.- References.- 5 Neurochemical Aspects of Thermoregulation.- 1 Introduction.- 2 Catecholamines.- 3 Indole Amines.- 4 Acetylcholine.- 5 Histamine.- 6 Peptides.- 7 Cations.- 8 Conclusion.- References.- 6 Avian Adjustments to Cold.- 1 General Introduction.- 2 Avian Body Temperature (Tb) and its Control.- 3 Thermogenic Responses.- 4 Substrate Metabolism in the Cold.- 5 Control of Thermolysis.- 6 Summary and Perspective.- References.- 7 Responses to Cold of Monotremes and Marsupials.- 1 Historical Perspective.- 2 Monotremes in the Cold.- 3 Marsupials in the Cold.- 4 Insights into the Evolution of Homeothermy?.- References.- 8 Aquatic Mammals in Cold.- 1 Introduction.- 2 Diversity of AquaticMammals.- 3 Thermal Challenges of the Aquatic Medium.- 4 Thermoregulatory Performance of Aquatic Mammals.- 5 Temperature Regulation Tactics.- 6 Summary and Conclusions.- References.- 9 Terrestrial Mammals in Cold.- 1 Introduction.- 2 Basal Metabolic Rate.- 3 Thermal Conductance and Insulation.- 4 Peripheral Heterothermy.- 5 Heat Production.- 6 Adaptations of Humans to Cold.- 7 Conclusions.- References.- 10 Ecological, Physiological, and Biochemical Aspects of Torpor in Mammals and Birds.- 1 Introduction.- 2 Physiological Manifestations in a Torpor Bout.- 3 Energetics of Torpor.- 4 Physiological and Biochemical Adaptations.- 5 Summary.- References.- 11 Cold, Energetics, and Populations.- 1 Introduction.- 2 Distribution Patterns.- 3 Abundance.- 4 Energy Budgets and Population Parameters.- 5 Summary and Conclusions.- References.