Food Webs

Food Webs

Food Webs

Food Webs


Human impacts are dramatically altering our natural ecosystems but the exact repercussions on ecological sustainability and function remain unclear. As a result, food web theory has experienced a proliferation of research seeking to address these critical areas. Arguing that the various recent and classical food web theories can be looked at collectively and in a highly consistent and testable way, Food Webs synthesizes and reconciles modern and classical perspectives into a general unified theory.

Kevin McCann brings together outcomes from population-, community-, and ecosystem-level approaches under the common currency of energy or material fluxes. He shows that these approaches--often studied in isolation--all have the same general implications in terms of population dynamic stability. Specifically, increased fluxes of energy or material tend to destabilize populations, communities, and whole ecosystems. With this understanding, stabilizing structures at different levels of the ecological hierarchy can be identified and any population-, community-, or ecosystem-level structures that mute energy or material flow also stabilize systems dynamics. McCann uses this powerful general framework to discuss the effects of human impact on the stability and sustainability of ecological systems, and he demonstrates that there is clear empirical evidence that the structures supporting ecological systems have been dangerously eroded.

Uniting the latest research on food webs with classical theories, this book will be a standard source in the understanding of natural food web functions.


I started thinking about this book after being approached by Sam Elworthy, who suggested a book based on recent food web theory, a synthesis of sorts. At about the same time, Joe Rasmussen, a friend and colleague at McGill told me that he believed no one understands recent food web theory. Taken together, I felt there was a need for such a book and that a synthesis with more attention to conceptual details was clearly in order. One of the more active research areas of late pertains to the “theory of weak interactions,” which I and numerous collaborators have played a role in developing. While this theory emphasizes weak interactions, it necessarily also considers the role of interactions of all strengths. This book seeks to illustrate how interaction strength governs the dynamics of food webs. As such, it is a very broadly based synthesis.

Nonetheless, the book does not cover all areas of food webs exhaustively nor does it attempt to. Further, as a monograph, it necessarily pays attention to work developed both in my laboratory and with my many excellent collaborators. At the end of each chapter I briefly scan empirical evidence. In some cases, this constitutes a review or meta-analysis, but frequently it is really just a cursory look at the emerging data and is done to promote further comparison among theory, experiment, and empirical patterns. Clearly this book is not a full review, as to provide such a review would be well beyond its scope.

The ideas laid out in this book are best developed with the language of mathematics, specifically dynamical systems. Thus, not surprisingly, this book has a fair amount of mathematics in it. However, I have made attempts to present it in an accessible format by constantly interpreting all mathematical logic within a biological framework. Further, I have tried to present the intuitive side of the results. You will see that much of this biological interpretation employs a bioenergetic framework. It just as easily could have been interpreted in terms of limiting nutrients or other relevant currencies, but this was the language of my Ph.D. advisor, Peter Yodzis, and I have grown accustomed to it.

For those who understand mathematics, I hope this book will be easy, and for those who do not, I hope they can harness the biological intuition behind these results and so contribute to the development of further food web theory (either theoretically or empirically). At a certain level, theory is about the development of heightened logical intuition, and so whether one understands . . .

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