Some 365 million years ago, a small group of lobe-finned fishes emerged from the Devonian swamps and ventured onto land, giving rise to the first terrestrial vertebrates— the amphibians. What evolutionary forces propelled these early tetrapods to give up their cozy aquatic existence for what must have been an uncertain and challenging terrestrial life is unknown, though a number of ideas are fiercely debated. Regardless of the evolutionary pressures involved in their origin, these early amphibians thrived and diversified, eventually giving rise to all terrestrial vertebrates—a vast and highly successful group. Today, there are nearly 6000 species of amphibians within three orders (frogs, salamanders, and caecilians) found in habitats ranging from tropical rainforests to deserts and Arctic tundra.
The study of amphibians has experienced a surge of interest in recent years, due in large part to both the recognition that amphibians worldwide are declining and the infusion of talent and funding to better understand the causes of these declines. Coincident with this expanding interest has been the publication in recent years of a number of excellent and significant books on amphibian biology, including Amphibian Declines, edited by Michael Lanno; The Ecology and Behavior of Amphibians, by Kentwood Wells; and Rise of the Amphibians, by Robert Carroll. Noticeably absent from this list has been a current synopsis of amphibian physiology; Ecological and Environmental Physiology of Amphibians seeks to fill this void and join the list of must-have books for the amphibian biologist.
Ecological and Environmental Physiology of Amphibians consists of a detailed review and synthesis of amphibian physiology, with emphasis on physiological mechanisms that allow amphibians to adapt to a wide range of environments and habitats. Authors Stan Hillman, Philip Withers, Robert Drewes, and Stan Hillyard all are recognized scientists who have made important contributions to our understanding of amphibian physiology. Reflecting the interests of the authors, the book has strong emphasis on water balance and respiration. This restricted focus is both its strength and its weakness—it gives the book coherence and allows the authors to write in their primary areas of expertise, yet it ignores large swaths of environmental physiology (e.g., environmental toxicology), limiting the appeal and utility of the book.
The book is divided in six long chapters. Chapter 1 provides an introduction to amphibian characteristics, phylogeny, and principles of physiology. Basic physiological systems in amphibians, including water and ion exchange, energy budgets, respiration, and cardiovascular dynamics, are discussed in chapter 2. The third chapter covers specialized physiological systems of amphibians (including skin and bladder adaptations for water and ion exchange, dehydration tolerance, temperature tolerance, metabolism, nitrogen excretion, and developmental plasticity), while chapter 4 explores physiological adaptations to extreme environments. In chapter 5, the authors discuss experimental techniques and approaches, and chapter 6 wraps things up by drawing conclusions about what we know, what we don't know, and future directions of the field.
Manageable in size, with 381 pages of primary text (469 pages total), Ecological and Environmental Physiology of Amphibians offers a strong phylogenetic approach and examples from a wide range of amphibian taxa. The book does a good job of portraying the science behind the principles, giving excellent coverage to the research literature. More than 1600 references, which appear to be current through 2007, provide an invaluable entre to the literature of amphibian physiology. Although advertised as accessible to graduate students, researchers in amphibian biology, and professional herpetologists, much of the book is technical and written largely for experienced physiologists. Equations are often used without defining variables, and complex terminology is introduced without explanation. I was disappointed to see so little introduction to general physiological principles, which would have been helpful to nonphysiologists and beginning students.
A noticeable shortcoming of the book is the almost exclusive focus on adult amphibians. Much physiological work has been done on larval amphibians, but this research is largely ignored in the present volume. Finally, given the current interest in amphibian declines and concerns about global climate change, one might expect to see emphasis given to physiological aspects of these current topics. Yet other than a few asides, these subjects are hardly mentioned. Discussion of how our current knowledge of amphibian physiology contributes to an understanding of amphibian responses to climate change, pollution, and emerging diseases would have greatly enhanced the book.
In summary, Ecological and Environmental Physiology of Amphibians is an important and significant resource, with an excellent review of the state of our current understanding of amphibian physiology, particularly with regard to water balance. The book is valuable to physiologists and to those amphibian biologists whose research focuses on water exchange, but I suspect that its usefulness to a wider audience is limited by its technical prose and restricted focus.
