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The physiological ecology of vertebrates. A view from energetics
Comparative Biochemistry and Physiology Part A 137 (2004) 245–246
Book Review
The physiological ecology of vertebrates. A view from energetics Brian K. McNab. Comstock Publishing Associates 2002. ISBN 0-8014-3913-2.
This book is a ‘must read’ for students and academics with an interest in physiological ecology. McNab uses a comparative, correlational approach to describe topics of scaling, temperature, water and salt balance, gas exchange, energetics of locomotion, energy budgets, diet and nutrition, and physiological limits to distributions. The book is aimed at advanced undergraduates, graduates, and professionals. Perusing the Table of Contents raises high expectations, from coverage of basic topics in comparative physiology to understanding the distributional limits of vertebrates from their physiology. The Foreward, Preface and Introduction raise expectations even further, in seeking a synthetic overview and underlying principles for physiological ecology from an energetic viewpoint. McNab says in his Preface that there is a ‘massive amount of data on many physiological systems derived from a diversity of species’ but a ‘general absence of an organizing theoretical framework’. His objective in this book is to demonstrate an intellectual cohesion for this field, at least for vertebrates, that emphasises a common thread of energy expenditure. But can such high expectations be satisfied? Part I (Foundations) provides an introductory window to the rest of the book. It introduces the adaptationist paradigm and puts it in an ecological context. It considers phylogenetic implications for demonstrating or falsifying that a character state is adaptive, but does not satisfactorily comment on modern comparative phylogenetic methods. Interesting examples abound in this chapter, but I am
left without a satisfying feeling at the end as to what it was all about. Do we have to worry about phylogeny or not? Should we vigorously examine ‘adaptations’ for falsifiability? Is it important if adaptations are restrictive or expansive? How do we determine if there are historical limits to adaptation? I was also annoyed by some inconsistencies in terminology and units, and figures being often more complex than necessary for the level of detail in the text. Part II (Thermal Exchange with the Environment) describes the scaling of metabolism and thermal relations, and adaptations to temperature for ectotherms and endotherms. There is an excellent (but long) discussion of endothermy and aspects of its evolution, and Bergmann’s Rule. Part III (Material Exchange with the Environment) provides a really interesting summary of osmotic and water exchange. Gas exchange is described with many interesting examples, but tends to be encyclopaedic. This section is the most removed from an underlying energetic basis, but aspects of energetics are provided where possible. Even though this book is primarily about vertebrates, a better perspective could have been provided by some judicious reference to invertebrates, since that is where the patterns for vertebrates came from (and some invertebrate material has been included in other sections, e.g. endothermic insects). Part IV (Ecological Energetics) covers the energetics of locomotion, energy budgets, periodicity (daily and annual) of energy budgets, and diet and nutrition. Swimming and running are clearly described, with many interesting examples, and aerobic and anaerobic contributions are analysed. Flight is described in considerable detail, and extrapolated to an interesting discussion of pterosaurs. The concept of energy budgets is presented with a clear historical description of methodological developments, culminating in field energy expenditure studies. The energetics of reproduction and growth are
1095-6433/04/$ - see front matter 䊚 2003 Elsevier Inc. All rights reserved. doi:10.1016/S1095-6433(03)00311-8
246
Book Review
described, along with the relevance of home range. Some interesting examples are given for vertebrates from energetically-restrictive environments (islands, caves, underground). Energy budget concepts are finally extended to energetics at the population level. Daily torpor and annual hibernation are presented as important mechanisms for sedentary vertebrates, and migration for mobile species. A general background is given to diversity of foods from energetic, ecological and morphological perspectives, but the chapter on diet and nutrition focuses on foregut and hindgut fermentation (as is reasonable since this is an important strategy for many groups of vertebrates) and secondary plant compounds as toxins (interesting in passing but not in detail). Part V (Consequences) is the culmination of the book, describing the significance of energetics for populations and physiological limits to geographic distributions. An interesting energetic perspective is given to topics such as generation time, fecundity, and population growth in placental vs. marsupial mammals, birds, and ectotherms. The last chapter (Physiological Limits to the Geographic Distribution of Vertebrates) was the one that I was most eager to read, but it was probably the most disappointing because of my unreasonable expectations. Having succinctly explained the problems associated with explaining limits to geographic distributions (multiplicity of factors), McNab nevertheless says that his book ‘represents the view that one of the ultimate expressions of physiological ecology is the limits to the distribution of vertebrates’. Although he provides many possible examples, few are very convincing. However, they are interesting and thought provoking, and should serve to stimulate future strategies for physiological ecologists to demonstrate physiological limitations to distributions (should they exist).
The extensive references (80 pages) are an invaluable asset to an interested reader, providing access to a diverse array of the physiological ecology literature. The subject and taxonomic indices are generally comprehensive and useful, but the subject index (like the text) tends to over-emphasise some topics at the expense of others This book is not a bland summary of physiological energetics; McNab takes the opportunity to offer his own insights and ideas. The reader might agree or disagree with some of McNab’s interpretations of physiological ecology, and might derive joy or frustration from his often complex figures that seek general patterns amongst diverse biological data sets. But, any zoologically curious reader would have to enjoy the sheer amount and diversity of information presented in this book. The constant stream of interesting topics is embellished with many and varied examples. There are however some annoying minor inconsistencies, a tendency for excessive detail in select topics, and a lack of generality and fundamental concepts. Overall, I highly recommend this book. I do not feel that it lived up to the high expectations it raised, of a synthetic overview and underlying principles for physiological ecology from an energetic viewpoint. Certainly the culmination of the book, physiological limits to geographical distribution, was disappointingly short of concrete examples. However, this is hardly a failing of McNab or his writing; rather it is a failing of the field of ecological energetics in providing general energetic doctrines.
Prof. Philip Withers Zoology, School of Animal Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia
Book Review
The physiological ecology of vertebrates. A view from energetics Brian K. McNab. Comstock Publishing Associates 2002. ISBN 0-8014-3913-2.
This book is a ‘must read’ for students and academics with an interest in physiological ecology. McNab uses a comparative, correlational approach to describe topics of scaling, temperature, water and salt balance, gas exchange, energetics of locomotion, energy budgets, diet and nutrition, and physiological limits to distributions. The book is aimed at advanced undergraduates, graduates, and professionals. Perusing the Table of Contents raises high expectations, from coverage of basic topics in comparative physiology to understanding the distributional limits of vertebrates from their physiology. The Foreward, Preface and Introduction raise expectations even further, in seeking a synthetic overview and underlying principles for physiological ecology from an energetic viewpoint. McNab says in his Preface that there is a ‘massive amount of data on many physiological systems derived from a diversity of species’ but a ‘general absence of an organizing theoretical framework’. His objective in this book is to demonstrate an intellectual cohesion for this field, at least for vertebrates, that emphasises a common thread of energy expenditure. But can such high expectations be satisfied? Part I (Foundations) provides an introductory window to the rest of the book. It introduces the adaptationist paradigm and puts it in an ecological context. It considers phylogenetic implications for demonstrating or falsifying that a character state is adaptive, but does not satisfactorily comment on modern comparative phylogenetic methods. Interesting examples abound in this chapter, but I am
left without a satisfying feeling at the end as to what it was all about. Do we have to worry about phylogeny or not? Should we vigorously examine ‘adaptations’ for falsifiability? Is it important if adaptations are restrictive or expansive? How do we determine if there are historical limits to adaptation? I was also annoyed by some inconsistencies in terminology and units, and figures being often more complex than necessary for the level of detail in the text. Part II (Thermal Exchange with the Environment) describes the scaling of metabolism and thermal relations, and adaptations to temperature for ectotherms and endotherms. There is an excellent (but long) discussion of endothermy and aspects of its evolution, and Bergmann’s Rule. Part III (Material Exchange with the Environment) provides a really interesting summary of osmotic and water exchange. Gas exchange is described with many interesting examples, but tends to be encyclopaedic. This section is the most removed from an underlying energetic basis, but aspects of energetics are provided where possible. Even though this book is primarily about vertebrates, a better perspective could have been provided by some judicious reference to invertebrates, since that is where the patterns for vertebrates came from (and some invertebrate material has been included in other sections, e.g. endothermic insects). Part IV (Ecological Energetics) covers the energetics of locomotion, energy budgets, periodicity (daily and annual) of energy budgets, and diet and nutrition. Swimming and running are clearly described, with many interesting examples, and aerobic and anaerobic contributions are analysed. Flight is described in considerable detail, and extrapolated to an interesting discussion of pterosaurs. The concept of energy budgets is presented with a clear historical description of methodological developments, culminating in field energy expenditure studies. The energetics of reproduction and growth are
1095-6433/04/$ - see front matter 䊚 2003 Elsevier Inc. All rights reserved. doi:10.1016/S1095-6433(03)00311-8
246
Book Review
described, along with the relevance of home range. Some interesting examples are given for vertebrates from energetically-restrictive environments (islands, caves, underground). Energy budget concepts are finally extended to energetics at the population level. Daily torpor and annual hibernation are presented as important mechanisms for sedentary vertebrates, and migration for mobile species. A general background is given to diversity of foods from energetic, ecological and morphological perspectives, but the chapter on diet and nutrition focuses on foregut and hindgut fermentation (as is reasonable since this is an important strategy for many groups of vertebrates) and secondary plant compounds as toxins (interesting in passing but not in detail). Part V (Consequences) is the culmination of the book, describing the significance of energetics for populations and physiological limits to geographic distributions. An interesting energetic perspective is given to topics such as generation time, fecundity, and population growth in placental vs. marsupial mammals, birds, and ectotherms. The last chapter (Physiological Limits to the Geographic Distribution of Vertebrates) was the one that I was most eager to read, but it was probably the most disappointing because of my unreasonable expectations. Having succinctly explained the problems associated with explaining limits to geographic distributions (multiplicity of factors), McNab nevertheless says that his book ‘represents the view that one of the ultimate expressions of physiological ecology is the limits to the distribution of vertebrates’. Although he provides many possible examples, few are very convincing. However, they are interesting and thought provoking, and should serve to stimulate future strategies for physiological ecologists to demonstrate physiological limitations to distributions (should they exist).
The extensive references (80 pages) are an invaluable asset to an interested reader, providing access to a diverse array of the physiological ecology literature. The subject and taxonomic indices are generally comprehensive and useful, but the subject index (like the text) tends to over-emphasise some topics at the expense of others This book is not a bland summary of physiological energetics; McNab takes the opportunity to offer his own insights and ideas. The reader might agree or disagree with some of McNab’s interpretations of physiological ecology, and might derive joy or frustration from his often complex figures that seek general patterns amongst diverse biological data sets. But, any zoologically curious reader would have to enjoy the sheer amount and diversity of information presented in this book. The constant stream of interesting topics is embellished with many and varied examples. There are however some annoying minor inconsistencies, a tendency for excessive detail in select topics, and a lack of generality and fundamental concepts. Overall, I highly recommend this book. I do not feel that it lived up to the high expectations it raised, of a synthetic overview and underlying principles for physiological ecology from an energetic viewpoint. Certainly the culmination of the book, physiological limits to geographical distribution, was disappointingly short of concrete examples. However, this is hardly a failing of McNab or his writing; rather it is a failing of the field of ecological energetics in providing general energetic doctrines.
Prof. Philip Withers Zoology, School of Animal Biology, The University of Western Australia, Crawley, Western Australia 6009, Australia