Ecological Physiology Of Daily Torpor And Hibernation

This book provides an in-depth overview on the functional ecology of daily torpor and hibernation in endothermic mammals and birds. The reader is well introduced to the physiology and thermal energetics of endothermy and underlying different types of torpor. Furthermore, evolution of endothermy as well as reproduction and survival strategies of heterothermic animals in a changing environment are discussed. Endothermic mammals and birds can use internal heat production fueled by ingested food to maintain a high body temperature. As food in the wild is not always available, many birds and mammals periodically abandon energetically costly homeothermic thermoregulation and enter an energy-conserving state of torpor, which is the topic of this book. Daily torpor and hibernation (multiday torpor) in these heterothermic endotherms are the most effective means for energy conservation available to endotherms and are characterized by pronounced temporal and controlled reductions in body temperature, energy expenditure, water loss, and other physiological functions. Hibernators express multiday torpor predominately throughout winter, which substantially enhances winter survival. In contrast, daily heterotherms use daily torpor lasting for several hours usually during the rest phase, some throughout the year. Although torpor is still widely considered to be a specific adaptation of a few cold-climate species, it is used by many animals from all climate zones, including the tropics, and is highly diverse with about 25-50% of all mammals, but fewer birds, estimated to use it. While energy conservation during adverse conditions is an important function of torpor, it is also employed to permit or facilitate energy-demanding processes such as reproduction and growth, especially when food supply is limited. Even migrating birds enter torpor to conserve energy for the next stage of migration, whereas bats may use it to deal with heat. Even though many heterothermic species will be challenged by anthropogenic influences such as habitat destruction, introduced species, novel pathogens and specifically global warming, not all are likely to be affected in the same way. In fact it appears that opportunistic heterotherms because of their highly flexible energy requirements, ability to limit foraging and reduce the risk of predation, and often pronounced longevity, may be better equipped to deal with anthropogenic challenges than homeotherms. In contrast strongly seasonal hibernators, especially those restricted to mountain tops, and those that have to deal with new diseases that are difficult to combat at low body temperatures, are likely to be adversely affected. This book addresses researchers and advanced students in Zoology, Ecology and Veterinary Sciences.

Hibernation and Torpor in Mammals and Birds explores the physiological factors that control hibernation and torpor in birds and mammals. This text covers topics ranging from metabolism in hibernation to the role of endocrines, respiration and acid-base state in hibernation, and theories of hibernation. This book is comprised of 14 chapters and begins with an overview of some clear-cut definitions and why mammals and birds hibernate. The reader is then introduced to the variations from euthermia that have been observed among birds and mammals. To give some structure to this listing, the approach is phylogenetic, starting with the birds and proceeding through the primitive to the more advanced mammals. Subsequent chapters explains the process of entering hibernation and the hibernating state, itself; capability of a species in natural hibernation to arouse from that state using self-generated heat; physiological changes at the start of a spontaneous arousal; and physiological mechanisms underlying the ability of hibernators to rewarm. Consideration is also given to intermediary metabolism in hibernation, cold adaptation of metabolism in hibernators, and the response of hibernators to various extrinsic influences such as neoplastic growth, radiation injury, and parasitism and symbionts. This book will be of interest to students and researchers in fields ranging from zoology to physiology and biophysics.

This book summarises the newest information on seasonal adaptation in animals. Topics include animal hibernation, daily torpor, thermoregulation, heat production, metabolic depression, biochemical adaptations, neurophysiology and energy balance. The contributors to this book present interdisciplinary research at multiple levels ranging from the molecular to the ecophysiological, as well as evolutionary approaches. The chapters of this book provide original data not published elsewhere, which makes it the most up-to-date, comprehensive source of information on these fields. The book’s subchapters correspond to presentations given at the 14th International Hibernation Symposium in August 2012 in Austria. This is a very successful series of symposia (held every four years since 1959) that attracts leading researchers in the field. Like the past symposia, this meeting – and consequently the book – is aimed not only at hibernation but at covering the full range of animal adaptations to seasonal environments. For the next four years, this book will serve as the cutting-edge reference work for graduate students and scientists active in this field of physiology and ecology. .

Numerous animal species live in environments characterized by a seasonal reduction in the availability of water, which often but not always occurs when temperatures are highest. For many such animals, survival during the toughest season requires spending long periods of time in a rather inactive state known as aestivation. But aestivation is much more than remaining inactive. Successful aestivation requires the selection of a proper microhabitat, variable degrees of metabolic arrest and responsiveness to external stimuli, the ability to sense the proper time of year for emergence, the preservation of inactive tissue, and much more. So, aestivation involves a complex collection of behaviors, ecological associations and physiological adjustments that vary across species in their type, magnitude and course. This book seeks to explore the phenomenon of aestivation from different perspectives and levels of organization, ranging from microhabitat selection to genetic control of physiological adjustments. It brings together authors from across the world working on different systematic groups, approaches, and questions, but who are all ultimately working to better understand the complex issue of aestivation.

Torpor or heterothermy corresponds to a state of depressed metabolism and is associated with specific metabolic, cellular and molecular adaptations that often occur on a seasonal basis. Yet the exact mechanisms and functioning of these changes are poorly understood. Interestingly, the potential of such extraordinary animal adaptation for human and animal health as well as other biomedical considerations has raised particular attention especially in the last decade. The strong metabolic and physiological adaptations of heterotherms can be of particular inspiration for current biomedical and pathological situations (e.g., obesity and related diseases, cardiovascular and metabolic dysfunctions, ischemia-reperfusion injuries, immune depression) and for the health and longevity of animal species, including humans.

Mammals are the so-called "pinnacle" group of vertebrates, successfully colonising virtually all terrestrial environments as well as the air (bats) and sea (especially pinnipeds and cetaceans). How mammals function and survive in these diverse environments has long fascinated mammologists, comparative physiologists and ecologists. Ecological and Environmental Physiology of Mammals explores the physiological mechanisms and evolutionary necessities that have made the spectacular adaptation of mammals possible. It summarises our current knowledge of the complex and sophisticated physiological approaches that mammals have for survival in a wide variety of ecological and environmental contexts: terrestrial, aerial, and aquatic. The authors have a strong comparative and quantitative focus in their broad approach to exploring mammal ecophysiology. As with other books in the Ecological and Environmental Physiology Series, the emphasis is on the unique physiological characteristics of mammals, their adaptations to extreme environments, and current experimental techniques and future research directions are also considered. This accessible text is suitable for graduate level students and researchers in the fields of mammalian comparative physiology and physiological ecology, including specialist courses in mammal ecology. It will also be of value and use to the many professional mammologists requiring a concise overview of the topic.

Contributors present the newest information on ecological, physiological, neurological, cellular and biochemical mechanisms by which vertebrates deal with seasonal cold.