David Costantini Oxidative Stress and Hormesis in Evolutionary Ecology and Physiology A Marriage Between Mechanistic and Evolutionary Approaches Oxidative Stress and Hormesis in Evolutionary Ecology and Physiology David Costantini Oxidative Stress and Hormesis in Evolutionary Ecology and Physiology A Marriage Between Mechanistic and Evolutionary Approaches 123 David Costantini Department of Biology University of Antwerp Wilrijk Belgium and Institute for Biodiversity, Animal Health and Comparative Medicine University of Glasgow Glasgow UK ISBN 978-3-642-54662-4 ISBN 978-3-642-54663-1 (eBook) DOI 10.1007/978-3-642-54663-1 Springer Heidelberg New York Dordrecht London Library of Congress Control Number: 2014934114 Ó Springer-Verlag Berlin Heidelberg 2014 This work is subject to copyright. 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Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) To my mother Preface Research programmes on oxidative stress and hormesis are wide ranging. Bio- medical and toxicological sciences have traditionally centralised such research, but in the last years we have seen the merger of laboratory-based biochemical and physiological approaches to the study of oxidative stress and hormetic mechanisms with ethological, ecological and evolutionary principles. Although research in this area is still in its infancy, many new fields of research are emerging from the marriage between these mechanistic and functional perspectives. What is critically lacking yet is a synthesis geared towards evolutionary ecologists, ecophysiologists and behavioural ecologists that seeks to consolidate a vast body of literature whilst, at the same time, remains sensitive to readers who may not have the depth of knowledge often necessary to navigate new fields of scientific enquiry. This book seeks to fill in this gap. Its goal is to synthesise and integrate research on oxidative stress and hormesis, but as seen from the perspective of an evolutionary ecologist or physiologist. Work in this area can open new frontiers for research to further our understanding on how and why biological diversity has evolved. This book does not have, however, the presumption to claim that oxidative stress or hormesis are vital, nor does it wish to fully describe biochemical mechanisms. Rather it wishes to emphasise that oxidative stress and hormesis are missing pieces of a complex biological puzzle. Focussing on these missing pieces and integrating them with other biological features can provide fascinating insights into how organisms work, how they evolve to sustain physiological function under a vast array of environmental conditions and why they work the way they do. The book is organised into ten chapters. Chapter 1 provides general historical information, definitions and background of research on oxidative stress physiol- ogy, hormesis and life history; Chaps. 2–10 analyse how oxidative stress and hormesis have influenced many aspects of life, from the incipient stages of development to the strategies of reproduction and the ways organisms age. While every chapter deals with a specific topic, it should not be forgotten that they are all related to each other. For example, when interpreting the effect of reproductive effort on oxidative damage, it is also important to consider that such effect will be possibly dependent on other aspects, like early life experiences, predation risk, or food quality and quantity. Moreover, the physiological machinery in turn may influence the way a specific factor impacts on the individual. For example, over evolutionary time, diet has been likely adjusted to the physiological needs of an vii viii Preface individual or species, while at the same time the physiological strategies have been adjusted to make use of what is present in the diet itself. We clearly need to integrate all this information in order to further our understanding of how variation in physiological systems and life history strategies comes out. In this regard, the term adaptation has been used in a general way throughout the book, including both real adaptations and exaptations. For a character to be regarded as an adaptation, it must be a derived character that evolved in response to a specific selective agent. The emergence of an antioxidant mechanism could have been maintained, for example, by natural selection because it confers current selective advantage, but this is not evidence of why it has been evolved. This means that protection against oxidative stress may not be the primary reason for why all antioxidant mechanisms have been evolved, but evolution of a certain antioxidant mechanism could have provided secondarily a selective advantage. Opportunities for studying truly natural processes are diminishing because pristine or near-pristine environments are rapidly shrinking and becoming more difficult to reach. This should remind us that we need to know more about how the changing and emerging environments are influencing natural animal populations. The many examples reported throughout the book will actually show how oxi- dative stress and hormesis can represent two important links between environ- mental changes and evolutionary fitness, hence they can represent two relevant tools of investigation for conservation biologists, as well. The book is not exhaustive, hence many relevant studies have not been included. The book has also never taken into consideration discussion of meth- odological approaches to quantify reactive species production, antioxidants or damage levels. Obviously, methods for the quantification of components of the redox machinery have to satisfy specific technical criteria. We have to recognise, however, that each method has limits; hence using a combination of more oxi- dative status parameters is essential. It is also crucial that the biochemistry of what is being measured is taken into consideration when interpreting experimental results. We have not to lose sight of the fact that there are also specific restrictions inherent to many ecological research programmes, such as the availability of only small amounts of blood and the requirement of non-terminal sampling. The biological meaning of many mechanisms or molecules that are currently measured to quantify damage or antioxidant defences is often hard to gauge, because most in-depth information about the physiological functions of many of them come from studies on a limited number of taxa. We also do not know in many cases what differences in oxidative stress mean; this is because we still do not know whether the impact on evolutionary fitness differs among oxidative damage parameters. Consequently, any generalisations and extrapolations about function should be made with considerable caution. Focusing too much on the limited array of model organisms generally used, and on highly conserved path- ways, narrows our understanding of what works under what circumstances. We need to appreciate that evolution has likely modified or changed the basic defence toolkit and that understanding how different organisms have solved the challenges posed by their environments and lifestyles is interesting and important. Preface ix The complexity and diversity of the natural world is a powerful experimental resource that is often forgotten by many scientific disciplines. Appreciating such a complexity will be instructive and will offer us new opportunities for exploring new frontiers of biological research. David Costantini Acknowledgments Above all I want to thank very much indeed Nadia Macciocchi, Fernando and Serena Costantini, Livia and Fernando Carello, who supported and encouraged me. I would like to thank very much Gianfranco Brambilla, Claudio Carere, Mauro Carratelli, Giacomo Dell’Omo, Alberto Fanfani, Neil Metcalfe and Pat Monaghan for valuable advice and support over my career. I also thank very much the following colleagues